Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
  • G01N33/54306—Solid-phase reaction mechanisms
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
  • G01N33/54353—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals with ligand attached to the carrier via a chemical coupling agent
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
  • G01N33/54366—Apparatus specially adapted for solid-phase testing
  • G01N33/54373—Apparatus specially adapted for solid-phase testing involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/58—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances
  • G01N33/582—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances with fluorescent label

Definitions

• the present disclosure relates to the fields of graphene materials, bioelectronic devices, and proteins.
• the present disclosure provides devices, comprising a biomolecule in electronic communication with a graphene body, the biomolecule having an optical absorption peak at around a particular wavelength of excitation illumination.
• the disclosure also provides methods, the methods including contacting a biomolecule to a graphene body such that the biomolecule and graphene body are placed into electronic communication with one another.
• devices including a graphene body in electronic communication with a biomolecule that preferentially binds a binding partner, the graphene body being in electronic communication with a biomolecule capable of detecting a change in an electronic characteristic of the biomolecule.
• the methods including illuminating a device with a wavelength of illumination, the device comprising a photosensitive protein having an optical absorption peak at around a particular wavelength of illumination, the photosensitive protein being in electronic communication with a body of graphene; and detecting a change in an electronic characteristic of the device.
• Figure 1 illustrates an AFM of monolayer graphene before (a) and after (b) functionalization with His-tagged protein G ( ⁇ scale bar for both images); z-scales are 8 nm and 20 nm, respectively), (c) Height linescans indicated on (a) and (b). (d) Schematic of chemical coupling between graphene (bottom) and the protein's histidine tag (top).
• Figure 2 presents current-gate voltage characteristic (I-VQ) of graphene FET after each step required for functionalization with fusion protein GST-BT5 : as prepared (black), after diazonium treatment (red dashed), after Ni-NTA attachment (green dotted), and after incubation in protein (GST-BT5) solution (blue dot-dash). Bias voltage is 1 mV.
• I-VQ characteristics of a GFP-GFET with different illumination conditions no illumination (black), and illumination at 405 nm (violet data), 532 nm (green data), and 632 nm (red data).
• Illumination intensity is approximately 70 mW/cm 2 for each wavelength.
• Bias voltage is 10 mV.
• Figure 3 presents photocurrent responses (% ⁇ / ⁇ ) of GFET hybrids
• GFP and YFP are determined by the proteins' optical absorption spectra. Responses are shown to illumination at 405 nm (violet data), 532 nm (green data), and 632 nm (red data), (a) Responses of GFP-GFET.
• Figure 4 presents AFM images of a monolayer graphene (a) before and (b) after incubation in 4-carboxybenzene diazonium tetrafluoroborate solution.
• the z scale is lOnm.
• Figure 5 presents AFM images of graphene (a) before and (b) after all functionalization steps except protein incubation.
• Z-scale is 15 nm.
• Figure 6 presents (a) AFM image of a monolayer graphene after
• FIG. 7 AFM images of a monolayer graphene (a) before and (b) after functionalization with a non-his-tag protein G.
• Z-axis scale is 15 nm.
• Figure 8 presents (a) Raman spectrum of of a pristine graphene and (b) Raman of the identical graphene after diazonium functionalization.
• Figure 9 presents Raman spectroscopy of monolayer graphene before (a) and after (b) functionalization with His-tagged protein G.
• Figure 10 illustrates a photocurrent responses of the graphene FET
• Figure 11 illustrates a percentage change of current vs time of the same device measured after two weeks.
• Figure 12 illustrates an exemplary reaction scheme for functionalization of graphene with Polyhistidine-Tagged Protein
• Figure 13 illustrates exemplary schemes for attaching proteins or other biomolecules to graphene substrates.
• biomolecules e.g., proteins
• biomolecules include olfactory receptors, antibodies or even antibody fragments capable of detection of disease biomarkers.
• Enzymes are also suitable biomolecules for use in the disclosed devices and methods. The specificity of the interaction between enzymes and their substrates makes enzymes particularly suitable for use in the disclosed devices and methods.
• the present disclosure first presents devices, the devices including a biomolecule in electronic communication with a graphene body, the biomolecule having an optical absorption peak at around a particular wavelength of excitation illumination.
• Biomolecules, antibodies, and antibody fragments are considered particularly suitable biomolecules for the disclosed devices.
• the biomolecule e.g., protein
• the biomolecule may be on that preferentially binds to one or more binding partners.
• Antibodies, enzymes, ligands, and receptors are considered particularly suitable for this purpose.
• biomolecules used the disclosed devices and methods may be isolated from nature or be synthetic in nature.
• a protein or other biomolecule used in the devices may include a histidine tag. Histitine- facilitated binding between proteins and graphene is considered especially suitable, but is not the only way in which biomolecules and graphene may be placed into electronic communication with one another.
• electronic communication between the biomolecule and the graphene body includes an interaction between a nickel-nitriloacetic acid group and a histidine residue.
• a protein may be bound to graphene by a peptide sequence.
• a protein may be attached to graphene by adding a specific peptide sequence, such as one that is identified using a phase display peptide library.
• Graphene may itself be modified to comprise a moiety to facilitate attachment.
• moieties include sugars, antibodies, a chitin binding protein, a maltose binding protein, glutathione-S-transferase (GST), an epitope tag, and the like.
• Suitable epitope tags include a V5- tag, a c-myc-tag, a HA-tag, or any combination thereof.
• Proteins used in the disclosed devices may include a reactive amino acid, which includes photoreactive amino acids.
• the graphene of the disclosed devices may include a diimide-activated amidation between the graphene and biomolecules.
• the devices may also include a cysteine- graphene linkage between the graphene and biomolecules. Such a linkage may be effected by treatment with diazonium, EDC NHS, PDEA aka 2-(2-pyrdinyldithio) ethaneamine, with a thiol- bearing region of the protein.
• linkages may be used to connect a biomolecule to graphene.
• Certain exemplary linkages and chemistries are shown in Figure 13, and include an amide bond between the biomolecules and graphene, an imine bond between the biomolecule and graphene, a thiourea bond between the biomolecule and graphene, an aminoalcohol bond between the biomolecule and graphene.
• the protein may be a fluorescent protein, a fusion protein, or both.
• a fluorescent protein may be a green fluorescent protein, a yellow fluorescent protein, a red fluorescent protein, a cyan fluorescent protein, or any combination thereof.
• a protein may include a fluorescent redox cofactor.
• a protein may include a flavoprotein, a heme containing protein wherein an iron has been substituted by zinc, and the like.
• a protein may include tryptophan, which is known to fluoresce.
• the wavelength of excitation illumination for the biomolecule may be between
• Green fluorescent protein 400 nm
• Enhanced green fluorescent protein 488 nm; Yellow fluorescent protein: 525 nm; Red fluorescent protein: 557 nm; Cyan fluorescent protein: 458 nm; Tryptophan containing proteins: 280 nm; flavin mononucleotide containing proteins: 450 nm. Proteins may have one, two, or more wavelengths.
• the graphene of the disclosed devices may be a sheet, a ribbon, a cylinder, a platelet, or virtually any other configuration.
• the graphene may be single-atom thickness or may have a thickness of multiple atoms.
• the graphene may thus comprise multiple sheets.
• the graphene of the devices is suitably in electronic communication with a device that monitors an electronic characteristic of the graphene body.
• the biomolecule and graphene bodies suitably comprise one or more moieties that bind to one another, coordinate with one another, or both.
• the biomolecule e.g., protein
• the biomolecule may include a histidine residue, which histidine residue may interact with one or more molecules associated with the graphene, which molecule may be a metal.
• the methods may include one or more carboxylic acid groups on the graphene body.
• the user may also attach a sugar, an antibody, a chitin binding protein, a maltose binding protein, glutathione-S-transferase (GST), an epitope tag, and the like to graphene.
• GST glutathione-S-transferase
• the electronic communication between the protein and the graphene body includes an interaction between a nickel-nitriloacetic acid group and a histidine residue.
• the present disclosure also provides additional devices. These devices suitably include a graphene body in electronic communication with a biomolecule that preferentially binds a binding partner, with the graphene body being in electronic communication with a device capable of detecting a change in an electronic characteristic of the biomolecule.
• the biomolecule is suitably a protein.
• the protein suitably features recognition capabilities for other proteins (e.g., cancer biomarkers) or for molecules in the environment.
• Olfactory receptors or other proteins that bind small molecules are considered especially suitable for such applications.
• Receptors, ligands, antibodies, antigens, enzymes, or even antibody fragments are all considered suitable biomolecules for these devices.
• the user may place the graphene into electronic communication with a device that monitors changes in an electronic characteristic of the device.
• a device that monitors changes in an electronic characteristic of the device.
• an associated change in an electronic characteristic of the device e.g., conductivity/resistance
• a device according to the present disclosure that includes an antibody complementary to antigen X may be contacted to a sample that may or may not contain antigen X.
• antigen X If antigen X is present, the antigen will bind to the antibody. The binding will in turn change an electronic characteristic of the device, which will then be registered by the device. If the antigen is not present in the sample, the electronic characteristics of the device will remain constant, and the user will understand that the analyte is not present.
• the devices may be constructed so as to include one, two, or more biomolecule detectors in electronic communication with graphene.
• the biomolecules may differ in terms of their binding affinities for different analytes, thus allowing for the construction of devices capable of simultaneously detecting the presence of two or more analytes.
• the devices are also capable of providing multiple biomolecules for detecting the same analyte, thus providing some redundancy in the device.
• the user may also contact the protein to a sample.
• samples may include a binding partner complementary to the protein, such as other proteins and other analytes.
• the user may contact a device having an antibody bound to graphene to a sample that may contain an analyte complementary to the antibody. The user may then detect a change in an electronic
• characteristic e.g., conductivity
• a user may also contact a sample to a device comprising graphene body in electronic communication with a biomolecule that preferentially binds a binding partner, the graphene body being in electronic communication with a device capable of detecting a change in an electronic characteristic of the protein; and monitoring a change in an electronic characteristic of the device related to binding between the biomolecule and binding partner.
• the graphene field effect transistor provides sensitive all-electronic readout of the protein's optical excitation.
• the approach thus enables creation of a family of bio/nano hybrid photodetectors, each sensitive to a wavelength range defined by proteinaceous components.
• proteins with different functionalities e.g., chemical affinity for particular biomarkers or small molecules in the liquid or vapor phase
• Exemplary experiments were performed on graphene produced by mechanical exfoliation onto oxidized silicon substrates.
• Graphene monolayers were selected by inspection with Atomic Force Microscopy (AFM) and Raman spectroscopy.
• Devices were functionalized with carboxylated diazonium salts, which readily form covalent bonds with graphene.
• the resulting carboxylic acid groups were activated with l-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride/sulfo- N-hydroxysuccinimide (EDC/sNHS), followed by attachment of nitrilotriacetic (NT A).
• Device fabrication was completed by adding Ni ions to the NTA complex, and incubation in protein solution (see Fig. 1(d)). Histidine-tagged proteins obtained commercially (protein-G (26.1 kDa), green fluorescent protein (GFP), and yellow fluorescent protein (YFP)) and a fusion protein were all successfully attached to graphene devices, illustrating the robustness and versatility of the approach.
• the His-tagged (recombinant) fusion protein is comprised of glutathione S-transferase (GST), 6 histidine residues, and "BT5", an artificial heme binding protein.
• Figure 1(a) and 1(b) are AFM images of the same graphene monolayer before and after functionalization with His-tagged protein-G, while Fig 1 (c) shows height profiles along the indicated linescans. Two changes are observed: a ⁇ 2-nm increase in baseline height of the functionalized graphene, and the appearance of particles of height 3.4 ⁇ 0.4 nm above the new baseline.
• AFM of graphene monolayers before and after incubation in diazonium solution showed height increases of - 0.5-nm height, in agreement with earlier reports.
• a ⁇ 2-nm height increase was found upon attachment of NTA, with no particles observed (data not shown). Without being bound to any single theory, one may associate the increased baseline height in Fig.
• FIG. 1 shows current-gate voltage (I-VQ) data from a GFET before and after subsequent processing steps resulting in attachment of fusion protein GST-BT5.
• Annealed GFET I-VG shows ambipolar behavior and carrier mobility of -2000 cm 2 /V-s for holes and electrons.
• the device After diazonium treatment (dashed data), the device appears p-type with hole mobility -300 cm 2 /Vs; and VN exceeds 80V, the maximum gate voltage used.
• the carrier mobility decrease is attributed to defects formed by sp 2 bond breaking and attached carboxybenzene groups;
• Proteinn-GFET bio/nano hybrid combines functionality of both components. Integration of photoactive proteins create hybridss with photoresponses tuned to desired wavelength ranges.
• Fig. 2(inset) shows I-VG data for GFP-GFET hybrid measured in the dark and when exposed to light of three different wavelengths (405 nm, 532 nm and 632 nm, referred to as violet, green, and red) at 70 mW/cm 2 intensity.
• a significant I-VG shift is observed only for violet illumination, with negligible change for green or red light.
• This wavelength-dependent photoresponse is consistent with the optical absorption spectrum of GFP, which is peaked near 400 nm with little absorption for wavelengths greater than 500 nm (inset to Fig. 3a; colored dots indicate wavelengths used).
• One may attribute the I-VG shift to a GFET electronic response to the photoexcitation of GFP.
• the observed current decrease may reflect a net dipole associated with charge redistribution in GFP upon photoexcitation, or GFP-GFET charge transfer since GFP is reported to be a light induced electron donor.
• Data in Fig. 3 provide information concerning bio/nano hybrids whose photocurrent response is determined by the optical properties of the protein component.
• the disclosed methods are robust and reproducible processes for bind His- Tagged proteins to graphene FETs. This in turn provides a pathway for construction of bio/nano hybrids integrating desirable functionalities of both components. AFM, Raman spectroscopy, and control experiments were used to confirm the hybrid structure, and transport measurements to assess electronic effects of protein attachment.
• FP-GFET hybrids present a new class of tunable photodetectors with photocurrent responses in a wavelength range determined by the absorption spectrum of the bound FP.
• FIG. 12 illustrates an exemplary functionalization process.
• Monolayer graphene on an oxidized silicon substrate was decorated with covalently bound carboxybenzene groups by immersion in a solution of 10.76 mM 4-carboxybenzene diazonium tetrafluoroborate (Best West Laboratories, Inc) at 55 oC for 1 h, followed by rising with acetone, methanol, and deionized (DI) water in sequence.
• DI deionized
• the chips were then incubated in a solution of 2 mM EDC (Sigma) 15 mM Sulfo-NHS (Thermo Scientific) activation buffer (0.1 M 2-(N- Morpholino)ethanesulfonic acid (MES) sodium salt, 0.5 M NaCl, pH adjusted to 6.0 with HCl) at room temperature for 15 min to activate the carboxylic acid of the carboxybenzene.
• EDC EDC
• Sulfo-NHS Thermo Scientific activation buffer
• MES 2-(N- Morpholino)ethanesulfonic acid
• the chips were washed with activation buffer and placed in a solution of 1 1.3 mM Na,Na-Bis(carboxymethyl)-L-lysine hydrate (NTA-NH2 (Aldrich) ) prepared with phosphate buffered saline (PBS; 0.1 M NaH2P04, 0.15 M NaCl, pH adjusted to 7.35 with NaOH) for 2 h.
• NTA-NH2 phosphate buffered saline
• PBS phosphate buffered saline
• NaH2P04 0.15 M NaCl, pH adjusted to 7.35 with NaOH
• His-tagged protein solution was pipetted onto the surface of the chips, followed by incubation for 30 min at room temperature. The solution droplet was large enough so that any volume change over the 30 min period due to evaporation was negligible. The chip was then rinsed with DI water to remove non-specifically bound proteins and blown dry.
• GFP was purchased from Millipore Corporation, and YFP was purchased from MBL International. His-tagged protein G was purchased from bio- World, and non his-tagged protein G for control experiments was purchased from ProSpec-Tany TechnoGene Ltd.
• FIG. 4 (a) (4 (b)) is a AFM image of graphene before (after) functionalization.
• the apparent height of the graphene is increased by -0.5 nm (associated with the carboxybenzene group; see Figure 12), and the surface is somewhat rougher.
• Figure 5 (a) (5 (b)) is an AFM scan of a graphene monolayer before (after) all steps of attachment chemistry except for incubation in protein solution.
• the apparent height of the graphene in Fig. S2(b) is increased by ⁇ 1.8 nm, reflecting attachment of the NTA molecular layer, motivating the assignment in the main text, Fig. 1 (c) and Figure 12. Only a few particlelike features are observed, in agreement with the interpretation that particle like features in Fig. 1 (b) are proteins linked to the graphene by their His-tag.
• Figure 8 (a) is the Raman spectrum of a graphene monolayer, which shows essentially no D peak.
• Figure 9 (b) is the Raman spectrum of the same graphene layer after diazonium incubation. D/G ratio has increased by more than an order of magnitude after diazonium functionalization, indicative of a significant level of sp3 bonded carbon due to the decoration with carboxybenzene groups (see Figure 12). similar to the result of graphene functionalized with protein.
• Figure 9 shows the Raman spectra of a pristine graphene monolayer (Fig. S6
• FIG. 12 A GFET was fabricated and all functionalization steps in Figure 12 were conducted except for a protein incubation step.
• Figure 10 shows that the device had no detectable photocurrent response at any of the wavelengths used in these experiments. This provides confirmation of the interpretation in the text that photocurrent responses are derived from the optical absorption spectra of the fluorescent proteins used.
• Figure 1 1 shows the measured photocurrent responses of the same device in Fig 3 (a) in main text measured two weeks later.
• Device responses to violet illumination were essentially identical to those observed immediately after the device was fabricated, indicating little change in the behavior of the GFP-GFET hybrid on the two week timescale.

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• 2012
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