WO2009017525A2 - Superparamagnetic colloidal nanocrystal structures - Google Patents
Superparamagnetic colloidal nanocrystal structures Download PDFInfo
- Publication number
- WO2009017525A2 WO2009017525A2 PCT/US2008/005430 US2008005430W WO2009017525A2 WO 2009017525 A2 WO2009017525 A2 WO 2009017525A2 US 2008005430 W US2008005430 W US 2008005430W WO 2009017525 A2 WO2009017525 A2 WO 2009017525A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- iron
- colloidal
- clusters
- nanocrystal clusters
- nanocrystal
- Prior art date
Links
- 239000002159 nanocrystal Substances 0.000 title claims abstract description 81
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims abstract description 121
- 230000005291 magnetic effect Effects 0.000 claims abstract description 104
- 238000000034 method Methods 0.000 claims abstract description 61
- 239000004038 photonic crystal Substances 0.000 claims abstract description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910001868 water Inorganic materials 0.000 claims abstract description 20
- 239000007864 aqueous solution Substances 0.000 claims abstract description 14
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 14
- 229920000867 polyelectrolyte Polymers 0.000 claims abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 64
- 239000000243 solution Substances 0.000 claims description 54
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 37
- 230000004044 response Effects 0.000 claims description 30
- 239000000377 silicon dioxide Substances 0.000 claims description 20
- 230000003287 optical effect Effects 0.000 claims description 18
- 239000002904 solvent Substances 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 16
- 238000001228 spectrum Methods 0.000 claims description 16
- 239000004094 surface-active agent Substances 0.000 claims description 16
- 239000011159 matrix material Substances 0.000 claims description 14
- 229920000642 polymer Polymers 0.000 claims description 14
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 10
- 229920002125 Sokalan® Polymers 0.000 claims description 9
- 239000002798 polar solvent Substances 0.000 claims description 9
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 238000001556 precipitation Methods 0.000 claims description 8
- 239000002243 precursor Substances 0.000 claims description 8
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 7
- 239000004584 polyacrylic acid Substances 0.000 claims description 7
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 150000007942 carboxylates Chemical class 0.000 claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 4
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims description 4
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 4
- 229920001223 polyethylene glycol Polymers 0.000 claims description 4
- XSOKHXFFCGXDJZ-UHFFFAOYSA-N telluride(2-) Chemical compound [Te-2] XSOKHXFFCGXDJZ-UHFFFAOYSA-N 0.000 claims description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 3
- 229910019142 PO4 Inorganic materials 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 235000021317 phosphate Nutrition 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
- PFKAKHILNWLJRT-UHFFFAOYSA-H 2-hydroxypropane-1,2,3-tricarboxylate;iron(2+) Chemical compound [Fe+2].[Fe+2].[Fe+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O PFKAKHILNWLJRT-UHFFFAOYSA-H 0.000 claims description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical class OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 2
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 claims description 2
- 229910021575 Iron(II) bromide Inorganic materials 0.000 claims description 2
- 229910021577 Iron(II) chloride Inorganic materials 0.000 claims description 2
- 229910021579 Iron(II) iodide Inorganic materials 0.000 claims description 2
- 229910021576 Iron(III) bromide Inorganic materials 0.000 claims description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-L Phosphate ion(2-) Chemical compound OP([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-L 0.000 claims description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical class OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 2
- 229920002845 Poly(methacrylic acid) Polymers 0.000 claims description 2
- 150000001408 amides Chemical class 0.000 claims description 2
- 229910021529 ammonia Inorganic materials 0.000 claims description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 2
- 125000002843 carboxylic acid group Chemical group 0.000 claims description 2
- 230000003247 decreasing effect Effects 0.000 claims description 2
- VEPSWGHMGZQCIN-UHFFFAOYSA-H ferric oxalate Chemical compound [Fe+3].[Fe+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O VEPSWGHMGZQCIN-UHFFFAOYSA-H 0.000 claims description 2
- 239000011640 ferrous citrate Substances 0.000 claims description 2
- 235000019850 ferrous citrate Nutrition 0.000 claims description 2
- 150000004678 hydrides Chemical class 0.000 claims description 2
- 150000004679 hydroxides Chemical class 0.000 claims description 2
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 2
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 claims description 2
- OWZIYWAUNZMLRT-UHFFFAOYSA-L iron(2+);oxalate Chemical compound [Fe+2].[O-]C(=O)C([O-])=O OWZIYWAUNZMLRT-UHFFFAOYSA-L 0.000 claims description 2
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims description 2
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 2
- KAEAMHPPLLJBKF-UHFFFAOYSA-N iron(3+) sulfide Chemical compound [S-2].[S-2].[S-2].[Fe+3].[Fe+3] KAEAMHPPLLJBKF-UHFFFAOYSA-N 0.000 claims description 2
- PVFSDGKDKFSOTB-UHFFFAOYSA-K iron(3+);triacetate Chemical compound [Fe+3].CC([O-])=O.CC([O-])=O.CC([O-])=O PVFSDGKDKFSOTB-UHFFFAOYSA-K 0.000 claims description 2
- 229910000155 iron(II) phosphate Inorganic materials 0.000 claims description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 2
- NPFOYSMITVOQOS-UHFFFAOYSA-K iron(III) citrate Chemical compound [Fe+3].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NPFOYSMITVOQOS-UHFFFAOYSA-K 0.000 claims description 2
- 229910000399 iron(III) phosphate Inorganic materials 0.000 claims description 2
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 2
- LNOZJRCUHSPCDZ-UHFFFAOYSA-L iron(ii) acetate Chemical compound [Fe+2].CC([O-])=O.CC([O-])=O LNOZJRCUHSPCDZ-UHFFFAOYSA-L 0.000 claims description 2
- GYCHYNMREWYSKH-UHFFFAOYSA-L iron(ii) bromide Chemical compound [Fe+2].[Br-].[Br-] GYCHYNMREWYSKH-UHFFFAOYSA-L 0.000 claims description 2
- BQZGVMWPHXIKEQ-UHFFFAOYSA-L iron(ii) iodide Chemical compound [Fe+2].[I-].[I-] BQZGVMWPHXIKEQ-UHFFFAOYSA-L 0.000 claims description 2
- SDEKDNPYZOERBP-UHFFFAOYSA-H iron(ii) phosphate Chemical compound [Fe+2].[Fe+2].[Fe+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O SDEKDNPYZOERBP-UHFFFAOYSA-H 0.000 claims description 2
- WALCGGIJOOWJIN-UHFFFAOYSA-N iron(ii) selenide Chemical compound [Se]=[Fe] WALCGGIJOOWJIN-UHFFFAOYSA-N 0.000 claims description 2
- SHXXPRJOPFJRHA-UHFFFAOYSA-K iron(iii) fluoride Chemical compound F[Fe](F)F SHXXPRJOPFJRHA-UHFFFAOYSA-K 0.000 claims description 2
- 239000003446 ligand Substances 0.000 claims description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 2
- KJUJKCNXQZCICQ-UHFFFAOYSA-N selanylideneiron(1+) Chemical compound [Fe+]=[Se] KJUJKCNXQZCICQ-UHFFFAOYSA-N 0.000 claims description 2
- UWHCKJMYHZGTIT-UHFFFAOYSA-N tetraethylene glycol Chemical compound OCCOCCOCCOCCO UWHCKJMYHZGTIT-UHFFFAOYSA-N 0.000 claims description 2
- FEONEKOZSGPOFN-UHFFFAOYSA-K tribromoiron Chemical compound Br[Fe](Br)Br FEONEKOZSGPOFN-UHFFFAOYSA-K 0.000 claims description 2
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 claims description 2
- 150000002505 iron Chemical class 0.000 claims 5
- KWIUHFFTVRNATP-UHFFFAOYSA-N glycine betaine Chemical compound C[N+](C)(C)CC([O-])=O KWIUHFFTVRNATP-UHFFFAOYSA-N 0.000 claims 2
- PSBDWGZCVUAZQS-UHFFFAOYSA-N (dimethylsulfonio)acetate Chemical group C[S+](C)CC([O-])=O PSBDWGZCVUAZQS-UHFFFAOYSA-N 0.000 claims 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims 1
- 238000004220 aggregation Methods 0.000 claims 1
- 230000002776 aggregation Effects 0.000 claims 1
- 150000001298 alcohols Chemical class 0.000 claims 1
- 150000001412 amines Chemical class 0.000 claims 1
- 229960003237 betaine Drugs 0.000 claims 1
- 150000001875 compounds Chemical class 0.000 claims 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims 1
- HEJPGFRXUXOTGM-UHFFFAOYSA-K iron(3+);triiodide Chemical compound [Fe+3].[I-].[I-].[I-] HEJPGFRXUXOTGM-UHFFFAOYSA-K 0.000 claims 1
- FZGIHSNZYGFUGM-UHFFFAOYSA-L iron(ii) fluoride Chemical compound [F-].[F-].[Fe+2] FZGIHSNZYGFUGM-UHFFFAOYSA-L 0.000 claims 1
- 230000010355 oscillation Effects 0.000 claims 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims 1
- 239000010452 phosphate Substances 0.000 claims 1
- 229920005862 polyol Polymers 0.000 claims 1
- 150000003077 polyols Chemical class 0.000 claims 1
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 claims 1
- 230000005415 magnetization Effects 0.000 abstract description 12
- 230000008569 process Effects 0.000 abstract description 7
- 230000007062 hydrolysis Effects 0.000 abstract description 5
- 239000012457 nonaqueous media Substances 0.000 abstract description 3
- 238000012377 drug delivery Methods 0.000 abstract description 2
- 230000003595 spectral effect Effects 0.000 abstract 1
- 239000002245 particle Substances 0.000 description 37
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 32
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 30
- 239000000084 colloidal system Substances 0.000 description 25
- 229910052681 coesite Inorganic materials 0.000 description 23
- 229910052906 cristobalite Inorganic materials 0.000 description 23
- 229910052682 stishovite Inorganic materials 0.000 description 23
- 229910052905 tridymite Inorganic materials 0.000 description 23
- 230000001965 increasing effect Effects 0.000 description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 11
- 239000004205 dimethyl polysiloxane Substances 0.000 description 11
- 235000019441 ethanol Nutrition 0.000 description 11
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 11
- 239000013078 crystal Substances 0.000 description 10
- 239000006185 dispersion Substances 0.000 description 10
- 230000008901 benefit Effects 0.000 description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 238000003786 synthesis reaction Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- 238000007614 solvation Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 238000003917 TEM image Methods 0.000 description 5
- 239000002131 composite material Substances 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000002441 reversible effect Effects 0.000 description 5
- -1 but not limited to Chemical class 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 230000003993 interaction Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 230000000737 periodic effect Effects 0.000 description 4
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- 239000004793 Polystyrene Substances 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 3
- 238000002056 X-ray absorption spectroscopy Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000012856 packing Methods 0.000 description 3
- 229920000058 polyacrylate Polymers 0.000 description 3
- 229920002223 polystyrene Polymers 0.000 description 3
- 238000000985 reflectance spectrum Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000011550 stock solution Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 238000001429 visible spectrum Methods 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000005294 ferromagnetic effect Effects 0.000 description 2
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000007885 magnetic separation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000012454 non-polar solvent Substances 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 239000013074 reference sample Substances 0.000 description 2
- 238000004098 selected area electron diffraction Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000004627 transmission electron microscopy Methods 0.000 description 2
- MFYSUUPKMDJYPF-UHFFFAOYSA-N 2-[(4-methyl-2-nitrophenyl)diazenyl]-3-oxo-n-phenylbutanamide Chemical compound C=1C=CC=CC=1NC(=O)C(C(=O)C)N=NC1=CC=C(C)C=C1[N+]([O-])=O MFYSUUPKMDJYPF-UHFFFAOYSA-N 0.000 description 1
- 238000005169 Debye-Scherrer Methods 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000000908 ammonium hydroxide Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000011258 core-shell material Substances 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 238000002296 dynamic light scattering Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
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- 238000005538 encapsulation Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 159000000014 iron salts Chemical class 0.000 description 1
- WTFXARWRTYJXII-UHFFFAOYSA-N iron(2+);iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Fe+2].[Fe+3].[Fe+3] WTFXARWRTYJXII-UHFFFAOYSA-N 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- FLTRNWIFKITPIO-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe] FLTRNWIFKITPIO-UHFFFAOYSA-N 0.000 description 1
- 150000002632 lipids Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000006249 magnetic particle Substances 0.000 description 1
- 238000002595 magnetic resonance imaging Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229940031182 nanoparticles iron oxide Drugs 0.000 description 1
- 229910001172 neodymium magnet Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000011356 non-aqueous organic solvent Substances 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000000399 optical microscopy Methods 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 125000002524 organometallic group Chemical group 0.000 description 1
- 230000005298 paramagnetic effect Effects 0.000 description 1
- 230000002688 persistence Effects 0.000 description 1
- 230000004962 physiological condition Effects 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000011163 secondary particle Substances 0.000 description 1
- 238000001338 self-assembly Methods 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- SCPYDCQAZCOKTP-UHFFFAOYSA-N silanol Chemical compound [SiH3]O SCPYDCQAZCOKTP-UHFFFAOYSA-N 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/02—Oxides; Hydroxides
- C01G49/08—Ferroso-ferric oxide [Fe3O4]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
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Definitions
- This invention relates to methods of forming superparamagnetic magnetite colloidal nanocrystal clusters and construction of colloidal photonic crystals using these clusters as building blocks.
- Superparamagnetic nanocrystals have proved to be very promising for biomedical applications as they are not subject to strong magnetic interactions in dispersion. Iron oxide nanocrystals have received the most attention for this purpose because of their biocompatibility and stability in physiological conditions.
- Several robust approaches have been developed for synthesizing magnetic iron oxide (e.g., ⁇ -Fe 2 O 3 or Fe 3 O 4 ) nanocrystals with tightly controlled size distribution, typically through organometallic processes at elevated temperatures in non-polar solvents. Additional steps of surface modification or lipid encapsulation are usually performed to transfer the hydrophobic nanocrystals from non-polar solvent to water for biomedical applications.
- the nanocrystals prepared using these methods have a low magnetization per particle so that it is difficult to effectively separate them from solution or control their movement in blood using moderate magnetic fields, thus limiting their usage in some practical applications such as separation and targeted delivery.
- Increasing the particle size increases the saturation magnetization, but also induces the superparamagnetic- ferromagnetic transition (at a particle size ⁇ 30 nra for Fe 3 O 4 ) so that nanocrystals are no longer dispersible in solution.
- the strategy of forming clusters of magnetite nanocrystals has the advantage of increasing the magnetization in a controllable manner while retaining the superparamagnetic characteristics.
- Photonic crystals are spatially periodic dielectric structures displaying photonic bandgaps in which certain optical modes can not exist. They have attracted much attention because of their important optoelectronic applications where manipulation of photons is required, for example, as photonic components intended for telecommunications, lasers, and sensors. Among these applications, a highly desirable feature is to have a tunable bandgap, which can be conveniently controlled by external stimuli.
- the present invention is directed to a chemical synthetic method for the production of monodisperse colloidal nanocrystal clusters (CNCs) of magnetite (Fe 3 O 4 ).
- CNCs monodisperse colloidal nanocrystal clusters
- the size of the clusters can be controlled from about thirty nanometers (nm) to about three hundred nm by using a high-temperature hydrolysis process.
- the combination of superparamagnetic property, high magnetization per particle, monodispersity, and high water dispersibility makes the CNCs ideal candidates for various important biomedical applications such as drug delivery, bioseparation, and magnetic resonance imaging.
- Each cluster is composed of many single magnetite crystallites of about ten nm, thus retaining the superparamagnetic properties at room temperature.
- the use of a surfactant in synthesis renders the clusters highly water dispersible.
- the CNCs show strong responses to external magnetic field due to their much higher magnetization per particle than that of individual magnetite "nanodots," which are defined herein as isolated particles each of which has a single crystalline domain.
- a “cluster” is defined herein as particles that are composed of many single crystallites.
- This invention also describes a magnetically tunable photonic crystal system by assembling highly charged superparamagnetic Fe 3 O 4 colloidal nanocrystal clusters (CNCs) in aqueous solution. Stabilized by the balance of attractive (magnetic) and repulsive (electrostatic) forces, the colloids form ordered structures along the direction of the external magnetic field with a regular interparticle spacing on the order of hundreds of nanometers. As a result, the solutions strongly diffract visible light.
- This novel photonic crystal system has several remarkable merits. Since the interparticle spacing is determined by the relative strengths of electrostatic repulsions and magnetic attractions, one can conveniently tune the diffraction wavelength throughout the entire visible spectrum by changing the strength of the external field.
- the optical response has also been found sensitive to both the size of the colloids and the ionic strength of the solution. Due to the high refractive index of iron oxide, strong diffraction is realized at a low volume fraction of particles (-0.06%). hi addition, a relatively weak magnetic field (-100-400 Gauss) is sufficient to induce the ordering of CNCs as a result of the high magnetic moment possessed by each particle.
- the optical response of the solutions to the variation of magnetic field is found to be fast, fully reversible, and compatible with miniaturization, suggesting great potential for uses in sensors, optical switches, and color displays.
- the concentration of stray electrolytes also has a strong effect on the optical response of the solution as it changes the strength of the interparticle electrostatic repulsion.
- Tunable photonic structures have also been formed in alkanol solutions by assembling silica coated Fe 3 O 4 CNC colloids using magnetic fields. Surface modification OfFe 3 O 4 CNCs with silica shells allows their dispersion in nonaqueous alkanol solutions. Both electrostatic and solvation forces contribute to the interparticle repulsion which counters the magnetically induced attractive force during the assembly of Fe 3 O 4 @SiO 2 colloids in alkanol solutions.
- the system reported here shows important features such as a fast, reversible and tunable optical response to external magnetic fields, high stability, and convenient control of the working diffraction range by changing the silica shell thickness.
- the ability to assemble the magnetic particles in nonaqueous solutions allows the fabrication of field-responsive polymer composite films for potential applications as displays or sensors.
- FIGURES Ia-If are transmission electron microscopy (TEM) images Of Fe 3 O 4 nanocrystal clusters in the present invention.
- FIGS. 2a-2c are high-resolution and high magnification TEM images of secondary structures for isolated colloidal nanocrystal clusters in the present invention.
- FIG. 2d is the selected area diffraction of an isolated colloidal nanocrystal cluster.
- FIG. 3 shows X-ray diffraction patterns confirming the secondary structure of magnetite colloidal nanocrystal clusters of the present invention and magnetite nanodots as a reference.
- FIG. 4 is a XAS spectrum at Fe L edge Of Fe 3 O 4 colloidal nanocrystal clusters and referential spectra for Fe 3 O 4 , 7-Fe 2 O 3 , Ot-Fe 2 O 3 .
- FIGS. 5a-5c show hysteresis loops of colloidal nanocrystal clusters of the present invention, wherein mass magnetization (M) is plotted as a function of applied external field.
- FIGS. 6a-6c show the aqueous dispersion of colloidal nanocrystal clusters of the present invention on a glass substrate.
- FIGS. 6d-6f show photos of a CNC aqueous dispersion in a vial with or without magnetic field applied.
- FIGS. 7a- 7b show the digital photos and reflectance spectra, respectively, of an aqueous solution of CNCs made in the present invention in response to a varying magnetic field at normal incidence.
- FIG. 8 shows the dependence of the tuning range of diffraction spectra of the colloidal photonic crystals, represented by the vertical bars, and the wavelength of maximum diffraction intensity, represented by the solid squares, on the size of CNCs.
- FIGS. 9a-9c show modulated optical responses OfFe 3 O 4 colloidal photonic crystals in a periodic magnetic field of different frequencies.
- FIGS. 10a- 1Oe show TEM images OfFe 3 O 4 colloidal nanocrystal clusters coated with silica layers of various thickness (Fe 3 O 4 @SiO 2 ).
- FIG. 11 shows reflection spectra of Fe 3 O 4 @SiO 2 in ethanol solution in response to an external magnetic field with varying strength.
- FIG.12 shows reflection spectra of Fe 3 ⁇ 4@SiO 2 colloids in various alkanol solvents in response to a defined magnetic field.
- FIG.13a shows fabrication procedure of a field-responsive PDMS composite embedded with droplets of EG solution of Fe 3 O 4 @SiO 2 colloid.
- FIG. 13b shows magnetically induced color change of a flexible PDMS film with EG solution of Fe 3 O 4 @SiO 2 colloids.
- the present invention is directed to superparamagnetic magnetite colloidal nanocrystal clusters (CNC) and methods of their production.
- Highly water soluble magnetite (Fe 3 O 4 ) CNCs are synthesized by a high temperature hydrolysis reaction using a precursor, a surfactant, a precipitation agent and a polar solvent.
- a NaOH/DEG stock solution was prepared by dissolving NaOH (50 mmol) in DEG (20 ml); this solution was heated at 120° C. for one hour under nitrogen, and cooled down and kept at 70° C.
- a mixture of PAA (4mmol), FeCl 3 (0.4 mmol) and DEG (17 ml) was heated to 220° C.
- the method of the present invention for forming colloidal nanocrystal clusters includes precursors chosen from iron salts including, but not limited to, iron (II) chloride, iron (III) chloride, iron (II) sulfate, iron (III) sulfate, iron (II) nitrate, iron (III) nitrate, iron (II)
- transition metals such as cobalt, nickel, and manganese can be incorporated into the synthesis by adding the corresponding salts so that the final products are iron based complex oxides.
- Suitable surfactants for use in the method of the present invention can be chosen from a wide range of polyelectrolytes such as, but not limited to those containing carboxylic acid groups including polyacrylic acid and polymethacrylic acid.
- Suitable polar solvents for use in the method of the present invention include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and polyethylene glycols.
- the precipitation of the colloidal nanocrystal clusters can be initiated by adding bases such as hydroxides, carbonates, bicarbonates, phosphates, hydrogen phosphate, dihydrogen phosphates of group 1 and 2, ammonium (for example, NaOH, KOH, Na 2 CO 3 , K 2 CO 3 ), ammonia, as well as group 1 salts of carbanions, amides and hydrides.
- bases such as hydroxides, carbonates, bicarbonates, phosphates, hydrogen phosphate, dihydrogen phosphates of group 1 and 2, ammonium (for example, NaOH, KOH, Na 2 CO 3 , K 2 CO 3 ), ammonia, as well as group 1 salts of carbanions, amides and hydrides.
- the reaction to form the colloidal nanocrystal clusters of the present invention can be carried out at a temperature between room temperature and the boiling point of the solvents. In one embodiment, the temperature for synthesis is controlled between about 100° C. to about 320° C.
- highly water soluble magnetite (Fe 3 O 4 ) CNCs are synthesized by using a high temperature hydrolysis reaction with polyacrylic acid (PAA) as the surfactant.
- PAA polyacrylic acid
- Iron (III) chloride (FeCl 3 ) is used as a precursor, and diethylene glycol, (DEG, a polyhydric alcohol with a boiling point of 244-245° C.) is used as a polar solvent.
- PAA was selected as the surfactant for the strong coordination of carboxylate groups with iron cations on the magnetite surface.
- An additional advantage of using PAA is that the uncoordinated carboxylate groups on the polymer chains extend to aqueous solution, conferring upon the particles a high degree of dispersibility in water.
- Ia-If obtained by measuring about 150 clusters for each sample, are 31 run, 53 run, 71 nm, 93 nm, 141 nm, and 174 run respectively, wherein all scale bars are 200 nm. Close inspection of these images confirms that these monodisperse colloids are consisted of small subunits.
- the size of the CNCs can be precisely controlled from -30 run to -300 nm by simply increasing the amount of NaOH while keeping all other parameters fixed (FIG. 1). This size tunability might be the result of slight differences in H 2 O concentration and alkalinity caused by varying NaOH additions. Higher H 2 O concentration and relatively stronger alkalinity could accelerate the hydrolysis of Fe 3+ , promoting the formation of larger oxide clusters.
- the growth of CNCs follows the well-documented two-stage growth model where primary nanocrystals nucleate first in a supersaturated solution and then aggregate into larger secondary particles.
- FIGS. 2a-2c The secondary structure of CNCs can be observed more clearly in FIGS. 2a-2c for isolated clusters of ⁇ 31nm, ⁇ 93nm, and -174 nm, respectively.
- Lattice fringes were recorded for a small cluster with diameter of 31 nm, as shown in the high-resolution TEM (HRTEM) image in FIG. 2a.
- HRTEM high-resolution TEM
- the cluster is composed of small subcrystals of 6-8 nm size and of the same crystal orientation. Measuring the distance between two adjacent planes in a specific direction gives a value of 0.482 nm, which corresponds to the lattice spacing of (11 1) planes of cubic magnetite.
- FIGS. 2b and 2c show the secondary structures of CNCs of much larger size.
- FIG. 2d shows selected- area electron diffraction (SAED) pattern recorded on an isolated cluster of -174 nm, which reveals a single-crystal-like diffraction where diffraction spots are seen to have widened into narrow arcs, indicating slight misalignments among the subcrystals.
- SAED selected- area electron diffraction
- XRD measurements also confirm the secondary structure of magnetite CNCs.
- FIGS. 5a and 5b show hysteresis loops of 93-nm CNCs measured at 300° K and 2° K, respectively.
- FIG. 5c is a comparison of hysteresis loops of 53-nm, 93-nm, 174-nm CNCs and a reference sample of 8-nm nanodots and the insert depicts the magnetic moment ( ⁇ ) per cluster (or dot) plotted in a logarithmic graph.
- the clusters show no remanence or coercivity at 300° K, corresponding to superparamagnetic behavior.
- FIG. 5c shows that all the CNCs, as the reference sample of 8-nm Fe 3 O 4 nanodots, are superparamagnetic at room temperature, i.e., 300° K.
- the saturation magnetization ( ⁇ s ) was determined to be 63.5 emu/g, 56.7 emu/g, 30.9 emu/g, 21.2 emu/g for 174-nm, 93-nm, 53-nm CNCs and 8-nm particles, respectively.
- the values for large clusters are close but decrease noticeably for small particles, which may be attributed to a surface related effect such as surface disorder or surface spin canting.
- the magnetic moment of an individual grain ( ⁇ ) can be determined by the Langevin paramagnetic function: M(x)-N ⁇ (cothx- (Ux)).
- the CNCs are highly water soluble even after washing with the mixture of ethanol and water for three times, thanks to the robust surface coating of PAA.
- the method of the present invention included the ability to visualize their magnetic responses in an optical microscope by observing a thin layer of aqueous dispersion of CNCs on a glass substrate.
- FIGS. 6a-6c show optical dark-field images of a thin layer of CNC aqueous dispersion on a glass substrate, without magnetic field, with magnetic field, and after the applied magnetic field is removed, respectively.
- the bright region at the lower-left corner in each image represents the dried CNCs.
- the initially well-dispersed CNCs shown in FIG. 6a forms chain-line structures when a magnetic field was applied.
- FIG. 6c The chain-like structures are disassembled immediately upon removing the external field, as seen in FIG. 6c, displaying a typical superparamagnetic behavior.
- Figures 6d-6f show photos of a CNC aqueous dispersion in a vial without magnetic field, with magnetic field, and after the applied magnetic field is removed, respectively. If a CNC solution is subjected to a strong magnetic field, the particles can be completely separated from the solution within minutes, as shown in FIGS. 6d and 6e. A slight agitation will bring the CNCs back into the original solution if the magnetic field is removed as shown in FIG. 6f.
- the present invention is further directed to a method for constructing colloidal photonic crystals out of the polyacrylate capped superparamagnetic magnetite (Fe 3 O 4 ) colloidal nanocrystal clusters (CNCs) with tunable size from about thirty to about three hundred nm using a high-temperature hydrolysis process.
- the colloidal photonic crystals show highly tunable diffractions covering the whole visible region owing to the highly charged polyacrylate covered surfaces and the strong magnetic responses of the magnetite CNCs.
- Uniform magnetite CNC building blocks were synthesized by hydrolyzing FeCl 3 with NaOH at about 220° C in a diethylene glycol (DEG) solution containing the surfactant of polyacrylic acid (PAA), which is described in the last section. These CNCs retain the superparamagnetic behavior at room temperature and show much stronger response to the external magnetic field than individual nanodots.
- DEG diethylene glycol
- PAA polyacrylic acid
- FIGS. 7a and 7b show the digital photos and reflectance spectra, respectively, of an aqueous solution of CNCs (approximately 10.2 mg/ml) in response to a varying magnetic field at normal incidence.
- the colloidal photonic crystals, shown in FIG. 7a, with magnetically tunable diffractions covering the whole visible spectra have been fabricated from superparamagnetic magnetite 120-nm CNCs.
- the magnetic field has been increased from 87.8 to 352 Gauss by moving a NdFeB magnet towards the sample (3.7 - 2.0 cm) with step size of 0.1 cm.
- the color of the aqueous solution of CNCs changes from red (in the vial 710) to blue (in the vial 720) as the magnetic filed increases.
- the diffraction peak resulting from the close pack (1 1 1) planes accordingly blue shifts under increasing magnetic filed as, for example, the peak 730 shifts to the peak 740.
- the peak frequency gradually shifts from about 750 nm to below 450 run. As the magnet moves away from the sample, the diffraction peak reversibly red shifts.
- a rapid response ( «1 s) of the diffraction to the change in the magnetic field is observed.
- the interplanar spacing decreases from 274 to 169 nm as the strength of magnetic field increases, as estimated by using the Bragg's Law ( ⁇ — Indsm ⁇ ), where ⁇ is the diffraction wavelength, n is the refractive index of water, d is the lattice plane spacing, and ⁇ - 90° is the Bragg angle.
- the three-dimensional order of the formed colloidal crystals is the result of the balance between the interparticle electrostatic repulsive force and the magnetic forces.
- the as synthesized CNCs without cleaning show no diffractions even when the magnetic field is so strong that they are separated from the solution.
- CNCs are composed of pure Fe 3 O 4 , their response to the external magnetic field is much stronger than that of the similarly sized polystyrene beads doped with iron oxide nanoparticles.
- the application of magnetic field results in additional magnetic packing forces, magnetic dipole-dipole repulsive and attractive forces.
- the magnetic packing force is exerted on every cluster and attracts them towards the maximum of local magnetic gradient.
- the repulsive and attractive forces are perpendicular and parallel to the magnetic field, respectively.
- the tuning range of the diffraction wavelength is found to relate to the average size of the CNCs.
- crystals of large-size clusters preferably diffract red light in a relatively weak magnetic field, and their ordered structures become unstable when the magnetic field is too strong.
- Small-size clusters (-60-100 nm) form ordered structures only when the magnetic field is sufficiently strong and the crystals preferably diffract blue light.
- the medium-size clusters can form stable colloidal crystals in a magnetic field with tunable diffractions covering the whole visible spectrum. To clearly reveal such size dependence, FIG.
- FIG. 8 plots the tuning range of colloidal photonic crystals, represented by the vertical bars, and the wavelength of maximum diffraction intensity, represented by the solid squares, against the size of CNCs. For each sample, the position of maximum diffraction intensity is determined by the polynomial fitting of the curve consisted of all peak values of the reflectance spectra, and the tuning range is obtained by including all the diffractions whose intensity is above 30 % of the maximum value.
- FIG. 8 indicates that the diffraction with maximum intensity red- shifts as the size increases approximately in a linear fashion, which agrees with our visual observations.
- FIG. 9a shows the reflection spectra of a 70 nm Fe 3 O 4 colloidal photonic crystals in a periodic magnetic field with a frequency of 0.5 Hz with spectra integration time of 200 msec. They demonstrate that the switch of diffraction at -470 nm between on and off states can be achieved with the same frequency as the external field.
- FIGS. 9a shows the reflection spectra of a 70 nm Fe 3 O 4 colloidal photonic crystals in a periodic magnetic field with a frequency of 0.5 Hz with spectra integration time of 200 msec. They demonstrate that the switch of diffraction at -470 nm between on and off states can be achieved with the same frequency as the external field.
- 9b and 9c show the variation of peak intensity at 470 nm in response to electromagnetic fields at higher frequencies such as 1 and 2 Hz with integration time of 100 msec.
- the diffraction intensity shows periodic modulations which closely match the profile of external field, displaying clear on/off states with the corresponding frequency. No gradual transition from longer wavelengths to the final shorter wavelength was observed during the development of the spectra, indicating that the ordered structures form within the first 200 msec upon the application of magnetic field. During the rest of the 'on' stage, the order of the crystals further improves as the remaining particles rearrange their positions.
- the diffraction peak disappears completely within 100-200 msec after the magnetic field is off, which is much faster than the time needed for development of translational order under a magnetic field.
- the present invention is further directed to a method of fabricating magnetically responsive photonic structures that can operate in nonaqueous solutions.
- the modification of the particle surface with a layer of silica allows their dispersion in various nonaqueous organic solvents such as alkanols.
- the modified particles in these nonaqueous solvents can also assemble into ordered structures and diffract light.
- the modification with silica layer also provides a convenient method for extending the diffraction wavelength beyond the visible range.
- Our synthetic procedure currently can produce Fe 3 O 4 CNCs with sizes below 300 nm, which limit the maximum diffraction wavelength to below -800 nm.
- the size limitation can be conveniently overcome by coating a layer of silica whose thickness can be precisely controlled by using the facile sol-gel processes.
- the silica coating also makes it possible to link a large variety of ligands to the particle surface through the well-developed silane chemistry for further enhancing the compatibility between the particles and solvents.
- FIGS. 10a- 1Oe show TEM images OfFe 3 O 4 colloidal nanocrystal clusters coated with silica layers of various thickness of 16.5, 25, 37, 56, and70.5 nm, respectively, where the CNCs have a similar core size of ⁇ 1 10 nm.
- Fe 3 O 4 @SiO 2 colloids were synthesized as follows. Fe 3 O 4 CNCs were synthesized using a high-temperature hydrolysis reaction reported previously. Fe 3 O 4 @SiO 2 core/shell colloids were prepared through a modified St ⁇ ber process.
- an aqueous solution (3 mL) containing Fe 3 O 4 CNCs ( ⁇ 25 mg) was mixed with ethyl alcohol (20 mL), ammonium hydroxide (28%, 1 mL) aqueous solution by vigorous stirring using mechanical stirrer.
- TEOS 0.1 mL was injected to the solution in every 20 min till the total amount of TEOS reaches 0.9 mL.
- reflection spectra of reaction solution were measured under magnetic field (622 Gauss) to monitor the thickness of silica layer.
- the Fe 3 O 4 @SiO 2 colloids were collected by magnetic separation, washed by ethanol for three times, and finally dispersed in ethanol (3 mL).
- Fe 3 O 4 @SiO 2 core-shell particles can be dispersed in a number of alkanol solvents and show a tunable optical response in the presence of an external magnetic field.
- the diffraction peak blue-shifts as the distance decreases from 4.3 to 1.9 cm with step size of 0.2 cm.
- FIG. 1 1 shows the typical reflection spectra of an ethanol solution of 170-nm (overall diameter with 1 14 nm in core size and 28 nm in shell thickness) Fe 3 O 4 @SiO 2 as a function of the external magnetic field strength, achieved by changing the magnet-sample distance.
- the diffraction intensity increases steadily with increasing external field strength until reaching a saturation value. Further increasing the strength of the magnetic field does not significantly change the peak position and the peak intensity drops only slightly.
- the solvation force may dominate the interparticle repulsions at small separations, making it possible to counter the induced magnetic attractive force and assemble the particles into ordered structures.
- the combined effect of these two repulsive forces leads to the skewed dependence profile of the diffraction to the changes in the strength of magnetic field.
- the thickness of the solvation layer By calculating the spacing from the shortest diffraction wavelength, we estimate the thickness of the solvation layer to be -20.4 nm which is close to the value reported in literature.
- the solvation force is also present in aqueous systems, however, its contribution to the overall repulsive interaction might be negligible in comparison to the strong electrostatic force resulted from high surface charges.
- Alkanol solutions of Fe 3 O 4 @SiO 2 colloids show significant long-term stability in photonic activity.
- slow release of ions from the environment or from the particles into the solution may eventually alter the photonic properties including both diffraction intensity and wavelength.
- the system reported here was able to display consistent photonic response after storage for several months, owing to the lower ionic strength of the alkanol solutions and the predominantly non-electrostatic contribution to interparticle repulsion.
- the diffraction spectra of the Fe 3 ⁇ 4@SiO 2 colloids can be modified by changing the thickness of the silica shell.
- TEOS was added to the reaction slowly and continuously during the synthesis.
- the Fe 3 ⁇ 4@SiO 2 colloids show an optical response to external magnetic field even in the original reaction solution (12.5% water, 4.2% NH 4 OH solution, and 83.3% ethanol), providing a convenient way to monitor the growth of silica layers around the Fe 3 O 4 cores.
- the detection method is fast in comparison to other measurement techniques such as dynamic light scattering or TEM imaging.
- Figures 10a- 1Oe show TEM measurements which confirm the increasing thickness of the silica shell from ⁇ 16 to ⁇ 70 nm. While the average diameter of the Fe 3 O 4 CNCs is below 180 nm as limited by the synthesis procedure, silica coating allows to increasing the effective particle size in a controlled manner so that the diffraction wavelength of the photonic crystals can be extended into the near-IR region.
- FIG. 12 shows the reflection spectra of 170-nm Fe 3 O 4 @SiO 2 colloids in various alkanol solvents in response to a same magnetic field of 622 Gauss.
- the applied magnetic field is strong enough to drive the neighboring particles close to "hard contact" so that the intensity of the diffraction is around the maximum value.
- the thickness of solvation layer (d' - (d - d co ⁇ o a)/2) in each solvent can be estimated from the calculated lattice spacing (d)
- the ability to assemble magnetic colloids into ordered structures in nonaqueous solvents represents a significant step towards the practical applications of these tunable photonic structures.
- the method of the present invention provides the ability to embed alkanol solutions of Fe 3 O 4 @SiO 2 colloids in a polydimethylsiloxane (PDMS) matrix in the form of liquid droplets, thus producing solid composite materials with field responsive optical properties. Similar operations have been extremely difficult using aqueous solutions due to the high polarity of water.
- Fe 3 ⁇ 4 @SiO 2 colloids are dispersed in a nonvolatile alkanol solvent such as EG, DEG, and glycerol, and then mixed with PDMS prepolymer and curing agent using mechanical stirring. Thanks to the high viscosity of prepolymer (3900 cp), EG solution of Fe 3 O 4 @SiO 2 forms very stable emulsion-like droplets with an average diameter of ⁇ 5 ⁇ m. The stability of droplets is also believed to benefit from the close match between the densities of the glycol and the PDMS matrix.
- a nonvolatile alkanol solvent such as EG, DEG, and glycerol
- FIG. 13a shows fabrication procedure of s field-responsive PDMS composite embedded with droplets of EG solution of Fe 3 O 4 @SiO 2 colloids and an optical microscopy graph of the droplets under a vertically aligned external magnetic field. The assembly of Fe 3 O 4 @SiO 2 colloids in the droplets under the magnetic field leads to the diffraction of green light.
- the droplets change color and show significantly increased contrast against the PDMS matrix under a vertically aligned magnetic field, and therefore can be easily observed and imaged. Careful inspection reveals that the droplets contain many bright spots, each of which represents a chain of Fe 3 O 4 @SiO 2 particles assembled along the magnetic field.
- Figure 13b shows magnetically induced color change of a flexible PDMS film with EG solution of Fe 3 O 4 @SiO 2 colloids.
- the composite film retains the flexibility of the PDMS matrix and can be folded into various shapes while still displaying magnetically induced colors.
- the material is also very stable, wherein no apparent degradations in optical or mechanical properties were observed after storing the samples for month.
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Abstract
Monodisperse colloidal nanocrystal clusters of magnetite (Fe3O4) with tunable sizes from about thirty to about three hundred nanometers have been synthesized using a high- temperature hydrolysis process. The colloidal nanocrystal clusters are capped with polyelectrolytes, and highly water soluble. Each cluster is composed of many single magnetite crystallites, thus retaining the superparamagnetic behavior at room temperature. The combination of superparamagnetic property, high magnetization, and high water dispersibility makes the colloidal nanocrystal clusters ideal candidates for various important biomedical applications such as drug delivery and bioseparation. The present invention is further directed to methods for forming colloidal photonic crystals from both aqueous and nonaqueous solutions of the superparamagnetic colloidal nanocrystal clusters with an external magnetic field applied thereto. The diffraction of the photonic crystals can be tuned from near infrared to visible and further ultraviolet spectral region by varying the external magnetic field.
Description
SUPERPARAMAGNETIC COLLOIDAL NANOCRYSTAL STRUCTURES
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/926,637, filed April 27, 2007, the contents of which are hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION This invention relates to methods of forming superparamagnetic magnetite colloidal nanocrystal clusters and construction of colloidal photonic crystals using these clusters as building blocks.
Recent advances in colloidal synthesis have enabled the preparation of high quality nanocrystals with controlled size and shape. Focus of synthetic efforts appear to be shifting to creation of secondary structures of nanocrystals, either by self-assembly or through direct solution growth. Manipulation of the secondary structures of nanocrystals is desired in order to combine the ability to harness the size-dependent properties of individual nanocrystals with the possibility to tune collective properties due to the interactions between the subunits.
Superparamagnetic nanocrystals have proved to be very promising for biomedical applications as they are not subject to strong magnetic interactions in dispersion. Iron oxide nanocrystals have received the most attention for this purpose because of their biocompatibility and stability in physiological conditions. Several robust approaches have been developed for synthesizing magnetic iron oxide (e.g., γ-Fe2O3 or Fe3O4) nanocrystals with tightly controlled size distribution, typically through organometallic processes at elevated temperatures in non-polar solvents. Additional steps of surface modification or lipid encapsulation are usually performed to transfer the hydrophobic nanocrystals from non-polar solvent to water for biomedical applications. The nanocrystals prepared using these methods, with dimensions of order ten nanometers (ran), have a low magnetization per particle so that it is difficult to effectively separate them from solution or control their movement in blood using moderate magnetic fields, thus limiting their usage in some practical applications such as separation and targeted delivery. Increasing the particle size increases the saturation magnetization, but also induces the superparamagnetic- ferromagnetic transition (at a particle size ~30 nra for Fe3O4) so that nanocrystals are no longer dispersible in solution. The strategy of forming clusters of magnetite nanocrystals
has the advantage of increasing the magnetization in a controllable manner while retaining the superparamagnetic characteristics.
Accordingly, what has been needed and heretofore unavailable are superparamagnetic nanocrystals that overcome the deficiencies of existing configurations so as to eliminate the problem of increasing the particle size producing nanocrystals that are not dispersible in solution. The present invention disclosed herein satisfies these and other needs.
Besides magnetic separation, these magnetite colloidal nanocrystal clusters also find its application in construct novel solution form photonic crystals. Photonic crystals are spatially periodic dielectric structures displaying photonic bandgaps in which certain optical modes can not exist. They have attracted much attention because of their important optoelectronic applications where manipulation of photons is required, for example, as photonic components intended for telecommunications, lasers, and sensors. Among these applications, a highly desirable feature is to have a tunable bandgap, which can be conveniently controlled by external stimuli. Although considerable efforts have been devoted along this direction by changing the refractive indices of the materials, the lattice constants or spatial symmetry of the crystals, the tunability has been typically limited to tens of nanometers in diffraction wavelength. A known system was developed from fabricated colloidal photonic crystals using charged polystyrene microspheres containing superparamagnetic nanoparticles. Changes in diffraction wavelength above one hundred nanometers can be achieved by imposition of magnetic fields.
SUMMARY OF THE INVENTION The present invention is directed to a chemical synthetic method for the production of monodisperse colloidal nanocrystal clusters (CNCs) of magnetite (Fe3O4). The size of the clusters can be controlled from about thirty nanometers (nm) to about three hundred nm by using a high-temperature hydrolysis process. The combination of superparamagnetic property, high magnetization per particle, monodispersity, and high water dispersibility makes the CNCs ideal candidates for various important biomedical applications such as drug delivery, bioseparation, and magnetic resonance imaging. Each cluster is composed of many single magnetite crystallites of about ten nm, thus retaining the superparamagnetic properties at room temperature. The use of a surfactant in synthesis renders the clusters highly water dispersible. The CNCs show strong responses to external magnetic field due to their much higher magnetization per particle than that of individual
magnetite "nanodots," which are defined herein as isolated particles each of which has a single crystalline domain. A "cluster" is defined herein as particles that are composed of many single crystallites.
Previously reported superparamagnetic iron oxide nanocrystals have typical dimensions of order ten nm. Due to their low magnetization per particle, it has been difficult to effectively separate them or control their movement in solution using moderate magnetic fields, thus limiting their usage in some practical applications. Increasing the particle size increases the saturation magnetization, but also induces the superpara- magnetic-ferromagnetic transition (at a particle size about thirty nm for Fe3O4) so that particles are no longer dispersible in solution. The strategy of forming clusters of magnetite nanocrystals has the advantage of increasing the magnetization in a controllable manner while retaining the superparamagnetic characteristics.
This invention also describes a magnetically tunable photonic crystal system by assembling highly charged superparamagnetic Fe3O4 colloidal nanocrystal clusters (CNCs) in aqueous solution. Stabilized by the balance of attractive (magnetic) and repulsive (electrostatic) forces, the colloids form ordered structures along the direction of the external magnetic field with a regular interparticle spacing on the order of hundreds of nanometers. As a result, the solutions strongly diffract visible light. This novel photonic crystal system has several remarkable merits. Since the interparticle spacing is determined by the relative strengths of electrostatic repulsions and magnetic attractions, one can conveniently tune the diffraction wavelength throughout the entire visible spectrum by changing the strength of the external field. The optical response has also been found sensitive to both the size of the colloids and the ionic strength of the solution. Due to the high refractive index of iron oxide, strong diffraction is realized at a low volume fraction of particles (-0.06%). hi addition, a relatively weak magnetic field (-100-400 Gauss) is sufficient to induce the ordering of CNCs as a result of the high magnetic moment possessed by each particle. The optical response of the solutions to the variation of magnetic field is found to be fast, fully reversible, and compatible with miniaturization, suggesting great potential for uses in sensors, optical switches, and color displays. The concentration of stray electrolytes also has a strong effect on the optical response of the solution as it changes the strength of the interparticle electrostatic repulsion. Other factors including the size, size distribution and concentration of the colloids have also been examined to optimize the diffraction intensity and tuning range.
Tunable photonic structures have also been formed in alkanol solutions by assembling silica coated Fe3O4 CNC colloids using magnetic fields. Surface modification OfFe3O4 CNCs with silica shells allows their dispersion in nonaqueous alkanol solutions. Both electrostatic and solvation forces contribute to the interparticle repulsion which counters the magnetically induced attractive force during the assembly of Fe3O4@SiO2 colloids in alkanol solutions. The system reported here shows important features such as a fast, reversible and tunable optical response to external magnetic fields, high stability, and convenient control of the working diffraction range by changing the silica shell thickness. The ability to assemble the magnetic particles in nonaqueous solutions allows the fabrication of field-responsive polymer composite films for potential applications as displays or sensors.
Other features and advantages of the present invention will become more apparent from the following detailed description of the invention, when taken in conjunction with the accompanying exemplary drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURES Ia-If are transmission electron microscopy (TEM) images Of Fe3O4 nanocrystal clusters in the present invention.
FIGS. 2a-2c are high-resolution and high magnification TEM images of secondary structures for isolated colloidal nanocrystal clusters in the present invention.
FIG. 2d is the selected area diffraction of an isolated colloidal nanocrystal cluster. FIG. 3 shows X-ray diffraction patterns confirming the secondary structure of magnetite colloidal nanocrystal clusters of the present invention and magnetite nanodots as a reference. FIG. 4 is a XAS spectrum at Fe L edge Of Fe3O4 colloidal nanocrystal clusters and referential spectra for Fe3O4, 7-Fe2O3, Ot-Fe2O3.
FIGS. 5a-5c show hysteresis loops of colloidal nanocrystal clusters of the present invention, wherein mass magnetization (M) is plotted as a function of applied external field. FIGS. 6a-6c show the aqueous dispersion of colloidal nanocrystal clusters of the present invention on a glass substrate.
FIGS. 6d-6f show photos of a CNC aqueous dispersion in a vial with or without magnetic field applied.
FIGS. 7a- 7b show the digital photos and reflectance spectra, respectively, of an aqueous solution of CNCs made in the present invention in response to a varying magnetic field at normal incidence.
FIG. 8 shows the dependence of the tuning range of diffraction spectra of the colloidal photonic crystals, represented by the vertical bars, and the wavelength of maximum diffraction intensity, represented by the solid squares, on the size of CNCs.
FIGS. 9a-9c show modulated optical responses OfFe3O4 colloidal photonic crystals in a periodic magnetic field of different frequencies.
FIGS. 10a- 1Oe show TEM images OfFe3O4 colloidal nanocrystal clusters coated with silica layers of various thickness (Fe3O4@SiO2).
FIG. 11 shows reflection spectra of Fe3O4@SiO2 in ethanol solution in response to an external magnetic field with varying strength.
FIG.12 shows reflection spectra of Fe3θ4@SiO2 colloids in various alkanol solvents in response to a defined magnetic field. FIG.13a shows fabrication procedure of a field-responsive PDMS composite embedded with droplets of EG solution of Fe3O4@SiO2 colloid.
FIG. 13b shows magnetically induced color change of a flexible PDMS film with EG solution of Fe3O4@SiO2 colloids.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to superparamagnetic magnetite colloidal nanocrystal clusters (CNC) and methods of their production. Highly water soluble magnetite (Fe3O4) CNCs are synthesized by a high temperature hydrolysis reaction using a precursor, a surfactant, a precipitation agent and a polar solvent. A NaOH/DEG stock solution was prepared by dissolving NaOH (50 mmol) in DEG (20 ml); this solution was heated at 120° C. for one hour under nitrogen, and cooled down and kept at 70° C. In a typical synthesis, a mixture of PAA (4mmol), FeCl3 (0.4 mmol) and DEG (17 ml) was heated to 220° C. in a nitrogen atmosphere for at least 30 min under vigorous stirring, forming a transparent light-yellow solution. A NaOH/DEG stock solution (1.75 ml) was injected rapidly into the above hot mixture, and the temperature dropped to about 210° C. instantly. The reaction solution slowly turned black after about two minutes and eventually slightly turbid. The resulting mixture was further heated for Ih to yield 93 -nm magnetite clusters. The amount of NaOH/DEG solution determines the size of the CNCs. For example, 1.6, 1.65, 1.7, 1.8, 1.85 ml of stock solutions lead to the formation of CNCs
with average sizes of 31, 53, 71, 141, 174 run, respectively. The final products were washed with the mixture of de-ionized (DI) water and ethanol several times and then dispersed in DI water.
The method of the present invention for forming colloidal nanocrystal clusters includes precursors chosen from iron salts including, but not limited to, iron (II) chloride, iron (III) chloride, iron (II) sulfate, iron (III) sulfate, iron (II) nitrate, iron (III) nitrate, iron
(II) fluoride, iron (III) fluoride, iron (II) bromide, iron (III) bromide, iron (II) iodide, iron
(III) iodide, iron (II) sulfide, iron (III) sulfide, iron (II) selenide, iron (III) selenide, iron (II) telluride, iron (III) telluride, iron(II) acetate, iron(III) acetate, iron(II) oxalate, iron(III) oxalate, iron(II) citrate, iron(III) citrate, iron(II) phosphate, iron(III) phosphate. Other transition metals such as cobalt, nickel, and manganese can be incorporated into the synthesis by adding the corresponding salts so that the final products are iron based complex oxides. Suitable surfactants for use in the method of the present invention can be chosen from a wide range of polyelectrolytes such as, but not limited to those containing carboxylic acid groups including polyacrylic acid and polymethacrylic acid. Suitable polar solvents for use in the method of the present invention include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and polyethylene glycols.
In the method of the present invention, the precipitation of the colloidal nanocrystal clusters can be initiated by adding bases such as hydroxides, carbonates, bicarbonates, phosphates, hydrogen phosphate, dihydrogen phosphates of group 1 and 2, ammonium (for example, NaOH, KOH, Na2CO3, K2CO3), ammonia, as well as group 1 salts of carbanions, amides and hydrides. The reaction to form the colloidal nanocrystal clusters of the present invention can be carried out at a temperature between room temperature and the boiling point of the solvents. In one embodiment, the temperature for synthesis is controlled between about 100° C. to about 320° C. In accordance with the present invention, the size of the clusters can be controlled from approximately thirty (30) nm to approximately three hundred (300) nm.
In one embodiment of the present invention, highly water soluble magnetite (Fe3O4) CNCs are synthesized by using a high temperature hydrolysis reaction with polyacrylic acid (PAA) as the surfactant. Iron (III) chloride (FeCl3) is used as a precursor, and diethylene glycol, (DEG, a polyhydric alcohol with a boiling point of 244-245° C.) is used as a polar solvent. PAA was selected as the surfactant for the strong coordination of carboxylate groups with iron cations on the magnetite surface. An additional advantage of
using PAA is that the uncoordinated carboxylate groups on the polymer chains extend to aqueous solution, conferring upon the particles a high degree of dispersibility in water. Introduction of sodium hydroxide (NaOH) into the hot mixture of DEG, FeCl3 and PAA produces water molecules and also increases the alkalinity of the reaction system, with both results favoring the hydrolysis of Fe3+. Under the reductive atmosphere provided by DEG at high temperature, Fe(OH)3 partially transforms to Fe(OH)2, finally leading to the formation OfFe3O4 particles through dehydration. These Fe3O4 nanocrystals spontaneously aggregate to form flower-like three-dimensional clusters, as shown in the representative transmission electron microscopy (TEM) images in FIGS. Ia-If. The average sizes of the CNCs in FIGS. Ia-If, obtained by measuring about 150 clusters for each sample, are 31 run, 53 run, 71 nm, 93 nm, 141 nm, and 174 run respectively, wherein all scale bars are 200 nm. Close inspection of these images confirms that these monodisperse colloids are consisted of small subunits.
The size of the CNCs can be precisely controlled from -30 run to -300 nm by simply increasing the amount of NaOH while keeping all other parameters fixed (FIG. 1). This size tunability might be the result of slight differences in H2O concentration and alkalinity caused by varying NaOH additions. Higher H2O concentration and relatively stronger alkalinity could accelerate the hydrolysis of Fe3+, promoting the formation of larger oxide clusters. The growth of CNCs follows the well-documented two-stage growth model where primary nanocrystals nucleate first in a supersaturated solution and then aggregate into larger secondary particles.
The secondary structure of CNCs can be observed more clearly in FIGS. 2a-2c for isolated clusters of ~31nm, ~93nm, and -174 nm, respectively. Lattice fringes were recorded for a small cluster with diameter of 31 nm, as shown in the high-resolution TEM (HRTEM) image in FIG. 2a. It's clear that the cluster is composed of small subcrystals of 6-8 nm size and of the same crystal orientation. Measuring the distance between two adjacent planes in a specific direction gives a value of 0.482 nm, which corresponds to the lattice spacing of (11 1) planes of cubic magnetite. The fact that subcrystals crystallographically align with adjacent ones can be understood as the result of oriented attachment and subsequent high temperature sintering during the synthesis. FIGS. 2b and 2c show the secondary structures of CNCs of much larger size. FIG. 2d shows selected- area electron diffraction (SAED) pattern recorded on an isolated cluster of -174 nm, which reveals a single-crystal-like diffraction where diffraction spots are seen to have widened into narrow arcs, indicating slight misalignments among the subcrystals.
XRD measurements also confirm the secondary structure of magnetite CNCs. FIG. 3 shows the diffraction patterns with almost identical broadenings for clusters of different sizes of 53-nm, 93-nm, and 174-nm and 8-nm magnetite nanodots, wherein peak positions and intensities recorded in the literature for bulk magnetite samples are indicated by the vertical bars. Calculations using Debye-Scherrer formula for the strongest peak (31 1) give grain sizes of 9.73, 9.65 and 10.83 nm for CNCs of size 53, 93 and 174 ran, respectively, implying that the subcrystals do not grow significantly with the increasing size of CNCs. Consistently, the peak shape and broadening in XRD patterns of CNCs are comparable to that of 8-nm isolated nanodots. We also confirmed the composition of iron oxide being magnetite by combining the XRD results with the X-ray absorption spectroscopy (XAS) measurements in FIG. 4.
The unique and complex structure allows CNCs to retain superparamagnetic behavior at room temperature even though their size exceeds 30 nm. FIGS. 5a and 5b show hysteresis loops of 93-nm CNCs measured at 300° K and 2° K, respectively. FIG. 5c is a comparison of hysteresis loops of 53-nm, 93-nm, 174-nm CNCs and a reference sample of 8-nm nanodots and the insert depicts the magnetic moment (μ) per cluster (or dot) plotted in a logarithmic graph. The clusters show no remanence or coercivity at 300° K, corresponding to superparamagnetic behavior. At 2° K, thermal energy is insufficient to induce moment randomization so that the clusters show typical ferromagnetic hysteresis loops with a remanence of 12.6 emu/g and a coercivity of 140 Oe.
To evaluate the magnetic response of CNCs to an external field, the mass magnetization (σ) was measured at 300° K by cycling the field between -20 kOe and 20 kθe. FIG. 5c shows that all the CNCs, as the reference sample of 8-nm Fe3O4 nanodots, are superparamagnetic at room temperature, i.e., 300° K. The saturation magnetization (σs) was determined to be 63.5 emu/g, 56.7 emu/g, 30.9 emu/g, 21.2 emu/g for 174-nm, 93-nm, 53-nm CNCs and 8-nm particles, respectively. The values for large clusters are close but decrease noticeably for small particles, which may be attributed to a surface related effect such as surface disorder or surface spin canting. The magnetic moment of an individual grain (μ) can be determined by the Langevin paramagnetic function: M(x)-Nμ(cothx- (Ux)).
The CNCs are highly water soluble even after washing with the mixture of ethanol and water for three times, thanks to the robust surface coating of PAA. The method of the present invention included the ability to visualize their magnetic responses in an optical microscope by observing a thin layer of aqueous dispersion of CNCs on a glass substrate.
FIGS. 6a-6c show optical dark-field images of a thin layer of CNC aqueous dispersion on a glass substrate, without magnetic field, with magnetic field, and after the applied magnetic field is removed, respectively. The bright region at the lower-left corner in each image represents the dried CNCs. As shown in FIG. 6b, the initially well-dispersed CNCs shown in FIG. 6a forms chain-line structures when a magnetic field was applied. The chain-like structures are disassembled immediately upon removing the external field, as seen in FIG. 6c, displaying a typical superparamagnetic behavior. Figures 6d-6f show photos of a CNC aqueous dispersion in a vial without magnetic field, with magnetic field, and after the applied magnetic field is removed, respectively. If a CNC solution is subjected to a strong magnetic field, the particles can be completely separated from the solution within minutes, as shown in FIGS. 6d and 6e. A slight agitation will bring the CNCs back into the original solution if the magnetic field is removed as shown in FIG. 6f.
The present invention is further directed to a method for constructing colloidal photonic crystals out of the polyacrylate capped superparamagnetic magnetite (Fe3O4) colloidal nanocrystal clusters (CNCs) with tunable size from about thirty to about three hundred nm using a high-temperature hydrolysis process. The colloidal photonic crystals show highly tunable diffractions covering the whole visible region owing to the highly charged polyacrylate covered surfaces and the strong magnetic responses of the magnetite CNCs. Such a system, with the advantages of simple and inexpensive to synthesize, wide and reversible tunability, and instant response to external magnetic field, opens the door to many critical applications including as active components in optical micro- electromechanical (MEMS) systems.
Uniform magnetite CNC building blocks were synthesized by hydrolyzing FeCl3 with NaOH at about 220° C in a diethylene glycol (DEG) solution containing the surfactant of polyacrylic acid (PAA), which is described in the last section. These CNCs retain the superparamagnetic behavior at room temperature and show much stronger response to the external magnetic field than individual nanodots. Polyacrylate binds to the particle surface through the strong coordination of carboxylate groups with iron cations, while the uncoordinated carboxylate groups on the polymer chains extend to aqueous solution and render the particles highly charged surfaces.
These Fe3O4 CNCs can readily self-assemble into colloidal crystals in deionized water upon application of a magnetic field; after removing the extra surfactants and decreasing the ionic strength through repeated centrifugation. FIGS. 7a and 7b show the
digital photos and reflectance spectra, respectively, of an aqueous solution of CNCs (approximately 10.2 mg/ml) in response to a varying magnetic field at normal incidence. The colloidal photonic crystals, shown in FIG. 7a, with magnetically tunable diffractions covering the whole visible spectra have been fabricated from superparamagnetic magnetite 120-nm CNCs. The magnetic field has been increased from 87.8 to 352 Gauss by moving a NdFeB magnet towards the sample (3.7 - 2.0 cm) with step size of 0.1 cm. As shown in FIG. 7a, the color of the aqueous solution of CNCs changes from red (in the vial 710) to blue (in the vial 720) as the magnetic filed increases. As shown in FIG. 7b, the diffraction peak resulting from the close pack (1 1 1) planes accordingly blue shifts under increasing magnetic filed as, for example, the peak 730 shifts to the peak 740. The peak frequency gradually shifts from about 750 nm to below 450 run. As the magnet moves away from the sample, the diffraction peak reversibly red shifts. A rapid response («1 s) of the diffraction to the change in the magnetic field is observed. The interplanar spacing decreases from 274 to 169 nm as the strength of magnetic field increases, as estimated by using the Bragg's Law (λ — Indsmθ), where λ is the diffraction wavelength, n is the refractive index of water, d is the lattice plane spacing, and θ - 90° is the Bragg angle. The three-dimensional order of the formed colloidal crystals is the result of the balance between the interparticle electrostatic repulsive force and the magnetic forces. The as synthesized CNCs without cleaning show no diffractions even when the magnetic field is so strong that they are separated from the solution. Their optical response to the magnetic field increases with the number of cleaning cycles which reduce the ionic strength of the solution and increases the Debye-Hiickel screening length and therefore the electrostatic repulsion, ξ-potential measurement of a sample cleaned five times gave a typical value of -51 mV, demonstrating their highly charged surface characteristics. Unlike the previously reported case for superparamagnetic polystyrene spheres, the CNCs do not form colloidal crystal in the absence of a magnetic field.
Since CNCs are composed of pure Fe3O4, their response to the external magnetic field is much stronger than that of the similarly sized polystyrene beads doped with iron oxide nanoparticles. The application of magnetic field results in additional magnetic packing forces, magnetic dipole-dipole repulsive and attractive forces. The magnetic packing force is exerted on every cluster and attracts them towards the maximum of local magnetic gradient. The repulsive and attractive forces are perpendicular and parallel to the magnetic field, respectively. For example, a 120-nm cluster shows a magnetic moment//
about 6.319xlO"14 emu in a 235 Gauss magnetic field, and experiences a magnetic packing force(Fm = V(μ£)) of 1.26x10"" dyn in a 200 Gauss-cm"1 gradient. With a 197.4 nm nearest-neighbor spacing d derived from the diffraction peak position, the interparticle repulsive force F™ = 3(μ2/cf) and the attractive force Fma = 6(μ2/<f) are estimated to be 9.9IxIO'7 and 1.98x10 6 dyn respectively. These values, which are negligible when the magnetic moment per particle is small, are now comparable to that of the interparticle electrostatic repulsive forces. It is also worth noting that the magnetic field required for inducing the ordering of the particles in the current system is ten times less than the previously reported value due to the much stronger magnetic moment of the Fe3O4 CNCs. The broad tunability and rapid responses of the current system may benefit from the large contribution of the magnetic forces in determining the crystal structure and the lattice constant.
The tuning range of the diffraction wavelength is found to relate to the average size of the CNCs. In general, crystals of large-size clusters (-160-180 nm) preferably diffract red light in a relatively weak magnetic field, and their ordered structures become unstable when the magnetic field is too strong. Small-size clusters (-60-100 nm) form ordered structures only when the magnetic field is sufficiently strong and the crystals preferably diffract blue light. As demonstrated by the example in FIG. 7b, the medium-size clusters can form stable colloidal crystals in a magnetic field with tunable diffractions covering the whole visible spectrum. To clearly reveal such size dependence, FIG. 8 plots the tuning range of colloidal photonic crystals, represented by the vertical bars, and the wavelength of maximum diffraction intensity, represented by the solid squares, against the size of CNCs. For each sample, the position of maximum diffraction intensity is determined by the polynomial fitting of the curve consisted of all peak values of the reflectance spectra, and the tuning range is obtained by including all the diffractions whose intensity is above 30 % of the maximum value. FIG. 8 indicates that the diffraction with maximum intensity red- shifts as the size increases approximately in a linear fashion, which agrees with our visual observations.
The optical responses of these photonic crystals are rapid and fully reversible. To characterize the response time, we recorded changes in the reflection spectrum of a magnetic colloidal photonic crystal in the presence of a periodically on-off magnetic field with a controllable switching frequency. FIG. 9a shows the reflection spectra of a 70 nm Fe3O4 colloidal photonic crystals in a periodic magnetic field with a frequency of 0.5 Hz
with spectra integration time of 200 msec. They demonstrate that the switch of diffraction at -470 nm between on and off states can be achieved with the same frequency as the external field. FIGS. 9b and 9c show the variation of peak intensity at 470 nm in response to electromagnetic fields at higher frequencies such as 1 and 2 Hz with integration time of 100 msec. As shown in Figures 9b and 9c, the diffraction intensity shows periodic modulations which closely match the profile of external field, displaying clear on/off states with the corresponding frequency. No gradual transition from longer wavelengths to the final shorter wavelength was observed during the development of the spectra, indicating that the ordered structures form within the first 200 msec upon the application of magnetic field. During the rest of the 'on' stage, the order of the crystals further improves as the remaining particles rearrange their positions. The diffraction peak disappears completely within 100-200 msec after the magnetic field is off, which is much faster than the time needed for development of translational order under a magnetic field.
Further modifications and improvements may additionally be made to the superparamagnetic magnetite colloidal nanocrystal clusters and methods of production disclosed herein without departing from the scope of the present invention. Accordingly, it is not intended that the invention be limited by the embodiments disclosed herein.
The present invention is further directed to a method of fabricating magnetically responsive photonic structures that can operate in nonaqueous solutions. Unlike the previously reported polyelectrolyte-grafted CNCs which are only dispersible in water, the modification of the particle surface with a layer of silica allows their dispersion in various nonaqueous organic solvents such as alkanols. Interestingly, upon application of an external magnetic field, the modified particles in these nonaqueous solvents can also assemble into ordered structures and diffract light. Given the expected diminished role for electrostatic forces for silica coated particles in alkanols, it is natural to suspect that other repulsive forces must be present to counter the magnetic attractive force and yield the observed persistence of ordering. The photonic response of the solutions to external fields suggests a rough range for this force and allows us to identify it with effects already observed in the literature. As well as allowing us to study fundamental details of interparticle forces, forming tunable photonic structures in nonaqueous solvents provides a number of advantages over the water-based approach for practical applications. For example, solvents with low volatility can now be used as dispersion media for improved long-term stability and ease of processing. The use of nonaqueous solvents also addresses the issue in the previous system where trace amount of ions released from environment
such as glass containers may gradually alter the system's photonic response. While maintaining the merits of our earlier work with aqueous colloids such as a fast and reversible response, the modification with silica layer also provides a convenient method for extending the diffraction wavelength beyond the visible range. Our synthetic procedure currently can produce Fe3O4 CNCs with sizes below 300 nm, which limit the maximum diffraction wavelength to below -800 nm. The size limitation can be conveniently overcome by coating a layer of silica whose thickness can be precisely controlled by using the facile sol-gel processes. The silica coating also makes it possible to link a large variety of ligands to the particle surface through the well-developed silane chemistry for further enhancing the compatibility between the particles and solvents.
FIGS. 10a- 1Oe show TEM images OfFe3O4 colloidal nanocrystal clusters coated with silica layers of various thickness of 16.5, 25, 37, 56, and70.5 nm, respectively, where the CNCs have a similar core size of ~1 10 nm. Fe3O4@SiO2 colloids were synthesized as follows. Fe3O4 CNCs were synthesized using a high-temperature hydrolysis reaction reported previously. Fe3O4@SiO2 core/shell colloids were prepared through a modified Stόber process. Typically, an aqueous solution (3 mL) containing Fe3O4 CNCs (~25 mg) was mixed with ethyl alcohol (20 mL), ammonium hydroxide (28%, 1 mL) aqueous solution by vigorous stirring using mechanical stirrer. TEOS (0.1 mL) was injected to the solution in every 20 min till the total amount of TEOS reaches 0.9 mL. At the end of every cycle, reflection spectra of reaction solution were measured under magnetic field (622 Gauss) to monitor the thickness of silica layer. After obtaining the desired size, the Fe3O4@SiO2 colloids were collected by magnetic separation, washed by ethanol for three times, and finally dispersed in ethanol (3 mL).
Fe3O4@SiO2 core-shell particles can be dispersed in a number of alkanol solvents and show a tunable optical response in the presence of an external magnetic field. The diffraction peak blue-shifts as the distance decreases from 4.3 to 1.9 cm with step size of 0.2 cm.
FIG. 1 1 shows the typical reflection spectra of an ethanol solution of 170-nm (overall diameter with 1 14 nm in core size and 28 nm in shell thickness) Fe3O4@SiO2 as a function of the external magnetic field strength, achieved by changing the magnet-sample distance. The diffraction intensity increases steadily with increasing external field strength until reaching a saturation value. Further increasing the strength of the magnetic field does not significantly change the peak position and the peak intensity drops only slightly. The contour of the peaks therefore shows a skewed profile. From the reflection spectra, one
can estimate an average value for interparticle spacings along the magnetic field using Bragg's law, λ = 2«ύfeinθ, as well as a surface-to-surface distance, ds.s, by subtracting the colloid diameter.
For the Fe3O4@SiO2 dispersions in ethanol, besides the electrostatic force, another repulsive force, "solvation force," must be considered besides the reduced electrostatic force when discussing the interactions in the framework of Derjaguin- Landau- Verwey- Overbeek (DLVO) theory. It has been widely accepted that for an ethanol dispersion of silica, a wetting film of solvent formed on the silica surface through the hydrogen bonds can significantly stabilize the system. When the solvation layers of two nearby particles overlap, a strong disjoining pressure appears to prevent the particles from coming together. While the electrostatic force still remains effective at larger separations, the solvation force may dominate the interparticle repulsions at small separations, making it possible to counter the induced magnetic attractive force and assemble the particles into ordered structures. The combined effect of these two repulsive forces leads to the skewed dependence profile of the diffraction to the changes in the strength of magnetic field. By calculating the spacing from the shortest diffraction wavelength, we estimate the thickness of the solvation layer to be -20.4 nm which is close to the value reported in literature. The solvation force is also present in aqueous systems, however, its contribution to the overall repulsive interaction might be negligible in comparison to the strong electrostatic force resulted from high surface charges.
Alkanol solutions of Fe3O4@SiO2 colloids show significant long-term stability in photonic activity. In the previous aqueous Fe3O4 CNC system, slow release of ions from the environment or from the particles into the solution may eventually alter the photonic properties including both diffraction intensity and wavelength. The system reported here was able to display consistent photonic response after storage for several months, owing to the lower ionic strength of the alkanol solutions and the predominantly non-electrostatic contribution to interparticle repulsion.
The diffraction spectra of the Fe3θ4@SiO2 colloids can be modified by changing the thickness of the silica shell. To avoid the homogeneous nucleation of small silica particles, TEOS was added to the reaction slowly and continuously during the synthesis. Interestingly, the Fe3θ4@SiO2 colloids show an optical response to external magnetic field even in the original reaction solution (12.5% water, 4.2% NH4OH solution, and 83.3% ethanol), providing a convenient way to monitor the growth of silica layers around the
Fe3O4 cores. The detection method is fast in comparison to other measurement techniques such as dynamic light scattering or TEM imaging. Figures 10a- 1Oe show TEM measurements which confirm the increasing thickness of the silica shell from ~ 16 to ~70 nm. While the average diameter of the Fe3O4 CNCs is below 180 nm as limited by the synthesis procedure, silica coating allows to increasing the effective particle size in a controlled manner so that the diffraction wavelength of the photonic crystals can be extended into the near-IR region.
Silanol surface makes the Fe3θ4@SiO2 colloids compatible with many alkanol solvents besides ethanol. FIG. 12 shows the reflection spectra of 170-nm Fe3O4@SiO2 colloids in various alkanol solvents in response to a same magnetic field of 622 Gauss. The applied magnetic field is strong enough to drive the neighboring particles close to "hard contact" so that the intensity of the diffraction is around the maximum value. In this case, the thickness of solvation layer (d' - (d - dco\\oa)/2) in each solvent can be estimated from the calculated lattice spacing (d) The ability to assemble magnetic colloids into ordered structures in nonaqueous solvents represents a significant step towards the practical applications of these tunable photonic structures. The method of the present invention provides the ability to embed alkanol solutions of Fe3O4@SiO2 colloids in a polydimethylsiloxane (PDMS) matrix in the form of liquid droplets, thus producing solid composite materials with field responsive optical properties. Similar operations have been extremely difficult using aqueous solutions due to the high polarity of water. In a typical process, Fe3θ4@SiO2 colloids are dispersed in a nonvolatile alkanol solvent such as EG, DEG, and glycerol, and then mixed with PDMS prepolymer and curing agent using mechanical stirring. Thanks to the high viscosity of prepolymer (3900 cp), EG solution of Fe3O4@SiO2 forms very stable emulsion-like droplets with an average diameter of ~5 μm. The stability of droplets is also believed to benefit from the close match between the densities of the glycol and the PDMS matrix. Curing the mixture at room temperature for ~24 hours (or at 600C for 2 hours) produces a dark brown silicone gel, which displays color change property when placed under a varying magnetic field. EG droplets remain intact during the curing process. Direct observation of the droplets using optical microscope has been difficult due to the close match between the refractive indices of EG (1.431) and PDMS (1.430). FIG. 13a shows fabrication procedure of s field-responsive PDMS composite embedded with droplets of EG solution of Fe3O4@SiO2 colloids and an optical microscopy graph of the droplets under a vertically
aligned external magnetic field. The assembly of Fe3O4@SiO2 colloids in the droplets under the magnetic field leads to the diffraction of green light. As shown in FIG. 13a, the droplets change color and show significantly increased contrast against the PDMS matrix under a vertically aligned magnetic field, and therefore can be easily observed and imaged. Careful inspection reveals that the droplets contain many bright spots, each of which represents a chain of Fe3O4@SiO2 particles assembled along the magnetic field. Figure 13b shows magnetically induced color change of a flexible PDMS film with EG solution of Fe3O4@SiO2 colloids. As shown in FIG. 13b, the composite film retains the flexibility of the PDMS matrix and can be folded into various shapes while still displaying magnetically induced colors. The material is also very stable, wherein no apparent degradations in optical or mechanical properties were observed after storing the samples for month.
Claims
1. A method for forming superparamagnetic magnetite colloidal nanocrystal clusters, comprising: providing an iron salt precursor, a polar solvent, a surfactant, and a precipitation agent having a concentration; mixing the iron salt precursor, the polar solvent, the surfactant, and the precipitation agent to initiate a hydrolysis reaction; and obtaining superparamagnetic magnetite (Fe3O4) colloidal nanocrystal clusters from a mixture resulting from the hydrolysis reaction.
2. The method of claim 1 , wherein the step of mixing comprises: mixing the iron salt precursor, the polar solvent, and the surfactant to produce a first mixture; and introducing the precipitation agent into the first mixture to initiate the hydrolysis reaction.
3. The method of claim 1, wherein the step of mixing comprises: mixing the iron salt precursor and the polar solvent to produce a first mixture; mixing the surfactant and the precipitation agent to produce a second mixture; and introducing the second mixture into the first mixture to initiate the hydrolysis reaction.
4. The method of claim 1, wherein the average size of each of the nanocrystal clusters ranges from about thirty nanometers to about three hundred nanometers.
5. The method of claim 4, further comprising controlling the average size of the nanocrystal clusters.
6. The method of claim 5, wherein controlling the average size of the nanocrystal clusters includes modulating the concentration of the precipitation agent while keeping all other parameters fixed so as to obtain the nanocrystal clusters of a desired value of average size.
7. The method of claim 1 , further comprising controlling the hydrolysis reaction to occur at a temperature ranging from about 100° C. to about 320° C.
8. The method of claim 1, wherein the superparamagnetic magnetite colloidal nanocrystal clusters are highly dispersible in aqueous solution.
9. The method of claim 1 , wherein the iron salt precursor is chosen from the group consisting of iron (II) chloride, iron (III) chloride, iron (II) sulfate, iron (III) sulfate, iron (II) nitrate, iron (III) nitrate, iron (II) fluoride, iron (III) fluoride, iron (II) bromide, iron (III) bromide, iron (II) iodide, iron (III) iodide, iron (II) sulfide, iron (III) sulfide, iron (II) selenide, iron (III) selenide, iron (II) telluride, iron (III) telluride, iron(II) acetate, iron(III) acetate, iron(II) oxalate, iron(III) oxalate, iron(II) citrate, iron(III) citrate, iron(II) phosphate and iron(III) phosphate.
10. The method of claim 1, wherein the polar solvent is chosen from the group consisting of chemical compounds containing multiple hydroxyl groups.
1 1. The method of claim 1 , wherein the polar solvent is chosen from the group consisting of polyols including ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and polyethylene glycols.
12. The method of claim 1, wherein the surfactant is chosen from the group consisting of polyelectrolytes.
13. The method of claim 12, wherein the surfactant is chosen from the group consisting of polyelectrolytes containing carboxylate, sulfonate, sulfate, phosphate, amine, ammonium, betaine and sulfobetaine groups.
14. The method of claim 13, wherein the surfactant is chosen from the group consisting of polyelectrolytes containing carboxylic acid groups.
15. The method of claim 1 , wherein the surfactant is chosen from the group consisting of polyacrylic acid and polymethacrylic acid.
16. The method of claim 1 , wherein the precipitation agent is chosen from the group consisting of hydroxides, carbonates, bicarbonates, phosphates, hydrogen phosphate, ammonia, group 1 salts of carbanions, amides, hydrides, and dihydrogen phosphates of group 1 , 2, and ammonium.
17. The method of claim 1, wherein obtaining nanocrystal clusters includes: obtaining superparamagnetic magnetite (Fe3O4) colloidal nanocrystals from the second mixture resulting from the hydrolysis reaction, and obtaining superparamagnetic magnetite (Fe3O4) colloidal nanocrystal clusters by the aggregation of the nanocrystals.
18. The method of claim 17, wherein the average size of each of the nanocrystals is of the order often nanometers.
19. The method of claim 18, wherein the average size of each of the nanocrystal clusters ranges from about thirtty nanometers to about three hundred nanometers.
20. The method of claim 1 , further comprising: coating the nanocrystal clusters with a layer of silica or polymer; and linking a ligand to the surface of the coated nanocrystal clusters.
21. A method of forming colloidal photonic crystals, comprising: providing superparamagnetic magnetite colloidal nanocrystal clusters formed by the method of claim 1; dispersing the nanocrystal clusters in an aqueous solution; and applying an external magnetic field on the nanocrystal clusters so as to form the colloidal photonic crystals from assemblage of the nanocrystal clusters in the polar solution, wherein the colloidal photonic crystals is tunable in lattice parameters and in diffraction frequency by varying the external magnetic filed.
22. The method of claim 21 , wherein the polar solution is chosen from the group consisting of water, alcohols, and other aqueous solutions.
23. The method of claim 21 , further comprising cleaning the colloidal photonic crystals, before applying the magnetic field, for removing extra surfactant on the nanocrystal clusters and decreasing ionic strength thereof.
24. The method of claim 21 , wherein the diffraction frequency of the colloidal photonic crystals under varying the external magnetic filed covers the entire visible region, the near-ultraviolet region, and the near-infrared region of the light spectrum.
25. The method of claim 21 , wherein when the external magnetic field is oscillating, the optical response of the colloidal photonic crystals follows the oscillation.
26. A method of forming colloidal photonic crystals, comprising: providing superparamagnetic magnetite colloidal nanocrystal clusters formed by the method of claim 1; modifying the surface of the nanocrystal clusters to be dispersible in nonaqueous solvents; dispersing the nanocrystal clusters in a nonaqueous solution; and applying an external magnetic field on the nanocrystal clusters so as to form the colloidal photonic crystals from assemblage of the nanocrystal clusters in the nonaqueous solution, wherein the colloidal photonic crystals is tunable in lattice parameters and in diffraction frequency under varying the external magnetic filed.
27. The method of claim 26, wherein the nonaqueous solution is chosen from the group consisting of alkanol solvents.
28. The method of claim 26, wherein modifying the surface of the nanocrystal clusters includes coating the nanocrystal clusters with a silica layer.
29. The method of claim 26, further comprising the step of tuning the thickness of the silica layer for further tuning the diffraction frequency under the external magnetic filed.
30. The method of claim 26, wherein the diffraction frequency of the colloidal photonic crystals under varying the external magnetic filed covers the entire visible region, the near-ultraviolet region, and the near-infrared region of the light spectrum.
31. A method of forming a polymer matrix containing droplets of superparamagnetic colloidal photonic crystals, comprising: providing superparamagnetic magnetite colloidal nanocrystal clusters formed by the method of claim 1; providing a solid polymer matrix; dispersing the nanocrystal clusters in an aqueous solution to produce a nanocrystal clusters solution; embedding droplets of the nanocrystal clusters solution into the solid polymer matrix; and applying an external magnetic field on the solid polymer matrix containing the nanocrystal cluster solution droplets so as to form colloidal photonic crystals in each of the droplets, wherein the colloidal photonic crystals is tunable in lattice parameters and in diffraction frequency by varying the external magnetic filed.
32. A method of forming a polymer matrix containing droplets of superparamagnetic colloidal photonic crystals, comprising: providing superparamagnetic magnetite colloidal nanocrystal clusters formed by the method of claim 1; providing a solid polymer matrix; modifying the surface of the nanocrystal clusters to be dispersible in nonaqueous solvents; dispersing the nanocrystal clusters in a nonaqueous solution to produce a nanocrystal clusters solution; embedding droplets of the nanocrystal clusters solution into the solid polymer matrix; and applying an external magnetic field on the solid polymer matrix containing the nanocrystal cluster solution droplets so as to form colloidal photonic crystals in each of the droplets, wherein the colloidal photonic crystals is tunable in lattice parameters and in diffraction frequency by varying the external magnetic filed.
33. The method of forming a polymer matrix of claim 32 further comprises, before applying the external magnetic field, curing the solid polymer matrix containing the nanocrystal cluster solution droplets.
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Publication number | Priority date | Publication date | Assignee | Title |
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6355166B1 (en) * | 1994-08-25 | 2002-03-12 | The University Of Iowa Research Foundation | Magnetically enhanced composite materials and methods for making and using the same |
US20060019096A1 (en) * | 2004-06-01 | 2006-01-26 | Hatton T A | Field-responsive superparamagnetic composite nanofibers and methods of use thereof |
US20060211941A1 (en) * | 2003-04-15 | 2006-09-21 | Koninklijke Philips Electronics N.V. | Arrangement and method for the spatially resolved determination of state variables in an examination area |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5206159A (en) * | 1984-11-01 | 1993-04-27 | Miles Inc., As Legal Successor By Merger With Technicon Instruments Corp. | Polymer particles containing colloidal iron oxide granules for use as a magnetically responsive reagent carrier |
ATE176077T1 (en) * | 1994-07-07 | 1999-02-15 | Chiron Diagnostics Corp | HIGHLY DISPERSED MAGNETIC METAL OXIDE PARTICLES, PRODUCTION PROCESS AND APPLICATION |
GB9600427D0 (en) * | 1996-01-10 | 1996-03-13 | Nycomed Imaging As | Contrast media |
KR100399475B1 (en) * | 1998-02-12 | 2003-09-29 | 보드 오브 리전츠, 더 유니버시티 오브 텍사스 시스템 | Methods and reagents for the rapid and efficient isolation of circulating cancer cells |
US7169618B2 (en) * | 2000-06-28 | 2007-01-30 | Skold Technology | Magnetic particles and methods of producing coated magnetic particles |
GB0313259D0 (en) * | 2003-06-09 | 2003-07-16 | Consejo Superior Investigacion | Magnetic nanoparticles |
US7534489B2 (en) * | 2004-09-24 | 2009-05-19 | Agency For Science, Technology And Research | Coated composites of magnetic material and quantum dots |
-
2008
- 2008-04-26 WO PCT/US2008/005430 patent/WO2009017525A2/en active Application Filing
- 2008-04-26 US US12/597,794 patent/US10118834B2/en active Active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6355166B1 (en) * | 1994-08-25 | 2002-03-12 | The University Of Iowa Research Foundation | Magnetically enhanced composite materials and methods for making and using the same |
US20060211941A1 (en) * | 2003-04-15 | 2006-09-21 | Koninklijke Philips Electronics N.V. | Arrangement and method for the spatially resolved determination of state variables in an examination area |
US20060019096A1 (en) * | 2004-06-01 | 2006-01-26 | Hatton T A | Field-responsive superparamagnetic composite nanofibers and methods of use thereof |
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US20170103833A1 (en) * | 2009-04-14 | 2017-04-13 | Snu R&Db Foundation | Method of forming microsphere having structural color |
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US10121952B2 (en) | 2009-04-23 | 2018-11-06 | The University Of Chicago | Materials and methods for the preparation of nanocomposites |
US9346998B2 (en) | 2009-04-23 | 2016-05-24 | The University Of Chicago | Materials and methods for the preparation of nanocomposites |
US10013647B2 (en) * | 2010-03-31 | 2018-07-03 | Quantamatrix Inc. | Method for magnetically controlling a magnetic structure |
US20130105581A1 (en) * | 2010-03-31 | 2013-05-02 | Sunghoon Kwon | Method for magnetically controlling a magnetic structure |
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US9180484B2 (en) | 2011-03-07 | 2015-11-10 | The Regents Of The University Of California | Magnetically responsive photonic nanochains |
WO2012122216A1 (en) | 2011-03-07 | 2012-09-13 | Yadong Yin | Magnetically responsive photonic nanochains |
US20140004275A1 (en) * | 2011-03-07 | 2014-01-02 | The Regents Of The University Of California | Magnetically responsive photonic nanochains |
US10600865B2 (en) | 2011-05-16 | 2020-03-24 | The University Of Chicago | Materials and methods for the preparation of nanocomposites |
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EP2726191A4 (en) * | 2011-07-01 | 2015-07-15 | Univ California | Direct assembly of hydrophobic nanoparticles to multifunction structures |
CN103357435A (en) * | 2012-03-28 | 2013-10-23 | 中国科学院理化技术研究所 | Composite magnetic nano material and preparation method thereof |
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CN105214090A (en) * | 2015-09-11 | 2016-01-06 | 吴晓红 | A kind of Fe 3o 4the synthetic method of ZnO core-shell nanospheres |
CN105214090B (en) * | 2015-09-11 | 2018-03-02 | 江苏经贸职业技术学院 | A kind of Fe3O4The synthetic method of@ZnO core-shell nanospheres |
WO2020021443A1 (en) | 2017-12-21 | 2020-01-30 | Ventiseidieci S.r.l. | Dynamic make-up product |
CN112533574A (en) * | 2017-12-21 | 2021-03-19 | 文蒂西迪奇有限责任公司 | Dynamic cosmetic product |
EP3501483A1 (en) | 2017-12-21 | 2019-06-26 | Ventiseidieci S.r.l. | Dynamic make-up product |
CN112533574B (en) * | 2017-12-21 | 2024-01-16 | 海德兰克责任有限公司 | Dynamic cosmetic product |
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US20100224823A1 (en) | 2010-09-09 |
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