RU2686931C1 - Method of producing rod-shaped magnetite nanoparticles - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention can be used in biomedicine for the diagnosis and treatment of malignant tumors. Method for producing rod-shaped magnetite nanoparticles involves preparing an aqueous suspension of a precursor, which is a rod of nanoparticles of akagenit, to which a solution of a reducing agent is added, which is a compound from the group of hydrazines with two free electrons. Specified solution of the reducing agent is added in an amount to ensure the reduction of iron Feto Fein alkaline conditions, characterized by pH 10–14. Resulting solution is irradiated with microwave radiation at 200±10 W and 90–100 °C for 30±2 sec. Reaction mass is cooled to room temperature. Resulting product is washed with deionized water to remove unreacted substances and dispersed in deionized water at neutral pH.EFFECT: invention allows to obtain rod-shaped magnetite nanoparticles with stability in aqueous solutions under physiological conditions and a narrow size distribution of nanoparticles ±10 nm, reduce the time of the process.6 cl, 5 dwg, 3 tbl, 4 ex

Description

Technical field

The invention relates to nanochemistry and relates to a method for producing rod-shaped magnetite nanoparticles that can be used in biomedicine, namely for the diagnosis and treatment of malignant tumors.

The level of technology

Magnetic nanoparticles (MNPs) of iron oxides (for example, magnetite or maghemite) belong to an important class of nanostructured materials, which are widely used in various fields of science, technology and biomedicine [Jeong U., Teng XW, Wang Y., Yang H., Xia YN, Adv. Mater. 2007, 19, 33-60, Xu C.J., Sun S.H. Polym. Int. 2007, 56, 821-826, Gupta A.K., Gupta M. Biomaterials 2005, 26, 3995-4021, Lu A.H., Salabas E.L., Schuth F. Angew. Chem., Int. Ed. 2007, 46, 1222-1244]

Compared with semiconductors and metal nanocrystals, MNPh iron oxides with non-spherical forms demonstrate the most attractive anisotropic magnetic properties [Chen M., Kim J., Liu J.P., Fan H.Y., Sun S.H.J. Am. Chem. Soc. 2006, 128, 7132-7133], thus of particular interest for biomedical applications.

, et al. Nanotechnologies in Russia, 2015, 570-575], маггемита γ-Fe₂O₃ [Bandhu, S. Sutradhar, S. Mukherjee, J.M. Greneche, P.K. Chakrabarti, Materials Research Bulletin, 2015, 70, 145-154], наночастицы чистых металлов, таких как Fe, Со

Ceramics International, 2015, 41, 11655-11661], ферритов: MgFe₂O₄, MnFe₂O₄, CoFe₂O₄ [Santi Phumying et al. Materials Research Bulletin, 2013, 48, 2060-2065] и т.д., а также разнообразных сплавов. Несмотря на более выраженные магнитные свойства наночастиц металлов по сравнению с наночастицами на основе оксидов железа, последние более устойчивы к окислению и менее токсичны [Sun S.Н. & Zeng Н. Size-controlled synthesis of magnetite nanoparticies. J. Am. Chem. Soc. 2002, 124, 8204-8205], и поэтому являются наиболее перспективными с точки зрения биомедицинского применения.To date, many approaches have been developed for the synthesis of magnetic nanoparticles of various elemental and phase compositions, including nanoparticles of iron oxides: magnetite Fe ₃ O ₄ [NV

, et al. Nanotechnologies in Russia, 2015, 570-575], maghemite γ-Fe ₂ O ₃ [Bandhu, S. Sutradhar, S. Mukherjee, JM Greneche, PK Chakrabarti, Materials Research Bulletin, 2015, 70, 145-154], nanoparticles of pure metals such as Fe, Co

Ceramics International, 2015, 41, 11655-11661], ferrites: MgFe ₂ O ₄ , MnFe ₂ O ₄ , CoFe ₂ O ₄ [Santi Phumying et al. Materials Research Bulletin, 2013, 48, 2060-2065], etc., as well as a variety of alloys. Despite the more pronounced magnetic properties of metal nanoparticles in comparison with nanoparticles based on iron oxides, the latter are more resistant to oxidation and less toxic [Sun S.N. & Zeng N. Size-controlled synthesis of magnetite nanoparticies. J. Am. Chem. Soc. 2002, 124, 8204-8205], and therefore are the most promising from the point of view of biomedical applications.

Rod-type iron oxide MNPs are of particular interest for biomedical applications, in particular for magnetic resonance imaging (MRI) as contrast agents. This is due to the fact that nanorods have a higher surface area compared to other forms, as well as good shape anisotropy, which makes a large contribution to the value of the coercive force (H _s ). Compared, for example, with spherical nanoparticles, the induced magnetic field of the rod is stronger and, consequently, the stronger the magnetic field in a large volume leads to an increase in R ₂ relaxation for nanorods.

The prior art synthesis of rod-like MNPs by the method of thermal decomposition of iron pentacarbonyl (Fe (CO) ₅ ) in the presence of oleic acid and hexadecylamine [N. Haiyan, V. Chen, X. Jiao, Z. Jiang, Z. Qin and D. Chen. Journal of Physical Chemistry, C. 2012, 116, 5476-5481]. In the process of synthesis, Fe (CO) ₅ first decomposes and oxidizes to form iron monoxide (FeO). Meanwhile, Fe (CO) ₅ reacts with oleic acid to form an iron (III) oleate complex. By controlling the reaction time and the amount of hexadecylamine, rod-shaped MNPs of various lengths and thicknesses can be obtained. However, for further use of such rod-shaped MNPs for biomedical purposes, additional modification of their surface is necessary in order to give them stability in aqueous media.

Rod-shaped magnetite nanoparticles were successfully obtained in an aqueous medium using microwave irradiation of akagenite β-FeOOH) in the presence of hydrazine hydrate as a reducing agent at pH values from 9.5 to 11.5 and a temperature of 100 ° C [I. Milosevic, N. Jouni, C. David, F. Warmont, D. Bonnin and L. Motte. Journal of Physical Chemistry, C. 2011, 115, 18999-19004]. The synthesis process consisted of several stages: 1) obtaining precursor rod-shaped nanoparticles (β-FeOOH) 2) synthesizing MNP from the precursor under the action of microwave radiation. Dopamine was used to obtain and stabilize rod-shaped nanoparticles. In the absence of the latter, the obtained nanoparticles had faceted shapes. However, the obtained nanoparticles have low stability and aggregate at physiological pH values, which does not allow them to be used for the therapy and diagnosis of malignant tumors.

The closest to the claimed (prototype) is a method for producing rod-shaped MNP by the method of aging in the presence of high molecular weight polyethylenimine [J. Mohapatra, A. Mitra, N. Tyagi, D. Bahadur and M. Aslam, Nanoscale, 2015, 1-26]. Polyethylenimine macromolecules are chemically adsorbed on the surface of short rod-shaped magnetite nanoparticles, thereby preventing their aggregation. This method is carried out in two stages, in the first stage of which, by heating an iron compound solution (iron (III) chloride) at 80 ° C in water in the presence of polyethyleneimine, a precursor is obtained, which in the second stage is mixed with oleylamine and heated to 200 ° C in the atmosphere inert gas (argon) followed by separation of the obtained rod-like nanoparticles. The disadvantage of the known method of producing rod-shaped magnetite nanoparticles is that the resulting nanoparticles lose their rod-like shape after the second stage, and also that such nanoparticles after the second stage are stable only in non-polar organic solvents (hexane, toluene), which necessitates an additional stage consisting in the stabilization of nanoparticles under physiological conditions. All this leads to complication, rise in price and increase the average duration of the work.

DISCLOSURE OF INVENTION

The present invention is to develop a method for producing rod-shaped magnetite nanoparticles with stability in aqueous solutions under physiological conditions.

The technical result of the proposed technical solution is that the obtained rod-shaped magnetite nanoparticles have stability in aqueous solutions under physiological conditions and a narrow size distribution of nanoparticles (± 10 nm). This result is achieved due to the fact that in the second stage of the inventive method, microwave radiation is used to restore the precursor, which allows nanoparticles to be restored without loosing the rod-like shape, and also to carry out the process in less time due to the rapid uniform heating of the entire solution volume while maintaining the size of the crystals, corresponding to the precursor (length and diameter). In addition, the resulting MNPs are stable in aqueous media without the need for an additional stage consisting in modifying their surface with stabilizing molecules.

The problem is solved by the claimed method of obtaining rod magnetite nanoparticles, which consists in preparing an aqueous suspension of a precursor, which is a rod of akagenite nanoparticles in which a reducing agent is added, characterized by the presence of two free electrons, in order to reduce iron Fe ³⁺ to Fe ²⁺ under alkaline conditions , characterized by pH = 10-14, when exposed to microwave radiation, after which the resulting solution is irradiated with microwave radiation at 200 ± 10 W and 90 ° C - 100 C for 30 ± 2 sec., Then the reaction mixture was cooled to room temperature, the resulting product was washed with deionized water to remove unreacted substances and dispersed in deionized water at neutral pH. The procedure of irradiation is repeated up to 4 times. As a reducing agent, it is preferable to use compounds from the group of hydrazines, namely, hydrazine hydrate, hydrosynium chloride, hydrosinium sulfate for the preparation of aqueous solutions with a concentration of 0.4 ± 0.1 mol / l, while taking 10 ± part of the suspension of acagenite in 10 vol. reducing agent solution. Aqueous suspension of the precursor is prepared with the content of [Fe] = 0.06 ± 0.01 mol / l and the reduction reaction of iron is carried out at pH = 10-14.

Irradiation of the solution with microwave radiation at 200 ± 10 W and 90 ° C - 100 ° C for 30 ± 2 seconds.

Stability under physiological conditions is the stability of MNP solutions at a temperature of 20-40 ° C, a pressure of 1 atmosphere, pH 6.5-8.

Brief Description of the Drawings

FIG. 1 is a micrograph and histograms of the size distribution of the obtained MNPs.

FIG. 2 shows the magnetization curve of the obtained MNPs.

FIG. 3 shows the diffraction pattern of the obtained nanopowder.

FIG. 4 shows the micrograph and histograms of the size distribution of the obtained MNPs (example 2).

FIG. 5 shows a micrograph of the MNP with the number of recovery cycles greater than 4.

The implementation of the invention

All reagents used are commercially available.

All procedures, unless otherwise specified, were carried out at room or ambient temperature, that is, in the range from 18 to 25 ° C.

The preparation of precursors - β-FeOOH rod-like NPs is carried out by the reaction of hydrolysis of an inorganic iron (III) salt (I. Milosevic, N. Jouni, C. David, F. Warmont, D. Bonnin, L. Motte. J. Phys. Chem. C , 2011, 115 (39), 18999-19004).

Suspension of the precursor - acagenite with the content [Fe] = 0.06 ± 0.01 mol / l is mixed with a solution of a reducing agent, characterized by the presence of two free electrons in an amount that ensures the reduction of iron Fe ³⁺ to Fe ²⁺ under alkaline conditions when exposed to microwave radiation . As reducing agents use compounds from the group of hydrazines, for example, hydrazine hydrate, hydrazinium sulfate, hydrazinium chloride). A solution of the reducing agent is prepared with a concentration of 0.4 ± 0.1 mol / l, while the solutions are mixed on the basis that 1 ± 0.5 volume part of the solution of reducing agent is taken on 10 parts of the suspension of acagenite. Bring the pH of the resulting suspension to 10-14. After that, the reaction mass is transferred to a hermetically sealed glass container and placed in a microwave synthesis reactor, which ensures uniform heating of the entire volume of the solution.

The resulting suspension is irradiated at 200 ± 10 W and 90 ° C - 100 ° C for 30 ± 2 seconds. Next, the reaction mass is cooled to room temperature, and the irradiation procedure is repeated from 1 to 4 times to obtain rod-like iron oxide nanoparticles. The resulting black-brown product is collected using a neodymium magnet, washed with deionized water to remove unreacted substances and dispersed in water at neutral pH. The nanoparticle solution is stored at a temperature from +4 to + 25 ° С.

The reaction mass is cooled at room temperature for at least 15 minutes. To speed up the cooling procedure, cooling is performed using compressed air of the compressor for 2-3 minutes.

Bringing the pH of the resulting suspension to 10-14 carry out any suitable reagents, for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide.

As the experiments showed, when the amount of radiation is more than 4 and when the time of irradiation is more than 30 s, magnetite nanoparticles lose their rod-like form with the formation of plates (Fig. 5).

The possibility of implementing the claimed invention is shown, but not limited, in examples of specific performance.

Example 1. Obtaining rod-shaped nanoparticles with a length of 40 nm.

Reagents and materials. Ferric chloride (III) (FeCl ₃ ; 97%), dopamine hydrochloride (DOPA), hydrazine hydrate (N ₂ H ₄ ^x H ₂ O; 50-60%) and sodium hydroxide (NaOH) were purchased from Sigma-Aldrich and used further without further purification. Hydrochloric acid (HCl) was acquired in the company "SigmaTek".

a) Preparation of the precursor (β-FeOOH rod-shaped nanoparticles)

10 ml of FeCl ₃ (0.5 mol / l) was prepared and mixed with 10 ml of HCl (0.04 mol / l) in a two-neck, 250 ml flask equipped with a thermometer and reflux condenser. Thereafter, 1.98 mg of DOPA was added to the resulting solution, and the resulting mixture was stirred for 10 minutes on a magnetic stirrer. After that, 180 ml of deionized water at a temperature of 80-90 ° C was poured into the flask with the prepared solution. The resulting solution was stirred for 2 hours at a temperature of 80-90 ° C. After this time, the solution was cooled to room temperature, and the pH was raised from 1.35 to 7-8 by adding a 1 M solution of 1 mol / L NaOH. An orange precipitate was observed.

The precipitate was separated from the solution by centrifugation (6000 rpm), washed with deionized water (3 × 50 ml) and dispersed in water at neutral pH. An orange colloidal suspension was obtained.

(фиг. 1).The performed x-ray structural analysis of the nanopowder indicates that the precursor obtained is acagenite

(Fig. 1).

b) Preparation of rod-shaped iron oxide nanoparticles based on a precursor

2 ml of the precursor suspension ([Fe] = 0.06 mol / l) was mixed with 40 μl of hydrazine hydrate solution (0.4 mol / l) and the pH of the resulting suspension was adjusted to 10.5 with a single molar solution of potassium hydroxide. After that, the reaction mass was transferred to a glass test tube, which was sealed and placed in a Monowave 300 microwave synthesis reactor.

The resulting suspension was irradiated at 200 W and 100 ° C for 30 seconds. Next, the reaction mass was cooled at room temperature to ambient temperature, and the irradiation procedure was carried out again. As a result, 4 cycles of irradiation were performed (20 min) according to the scheme described above. The resulting black-brown product was collected using a neodymium magnet, washed with deionized water (2 × 20 ml) and dispersed in water at neutral pH.

As can be seen from the micrographs shown (Fig. 2), the obtained nanoparticles have a rod-like shape and a rather narrow size distribution (± 10 nm). Processing the resulting precursor with microwave radiation did not lead to the loss of a rod-shaped EFF.

The X-ray diffraction study shows that the obtained rod-like nanoparticles consist of the pure magnetite phase (Fig. 3).

Example 2. Preparation of rod-shaped magnetite nanoparticles with a length of 20 nm.

Reagents and materials. Ferric (III) chloride (FeCl ₃ ; 97%), polyethyleneimine (PEI, branched, M _w ≈25000 g * mol ^-1 ) were purchased from Sigma-Aldrich and used without further purification. Deionized water was obtained using the MIlli-Q Water deionizer.

a) Preparation of the precursor (β-FeOOH rod-shaped nanoparticles).

The core-shaped β-FeOOH nanoparticles were obtained by hydrolysis of an aqueous solution of FeCl ₃ . To synthesize 20 nm nanoparticles of akagenit in a two-neck flask, 10 ml of FeCl ₃ solution (2 mol / l) was mixed with 10 ml of hydrochloric acid solution with a concentration of 0.04 mol / l, after which 2 ml of PEL were added. After that 100 ml of deionized water, previously heated to 80 ° C, was poured into the reaction mixture. The temperature of the reaction mixture was maintained at 80 ° C with vigorous stirring for 2 hours to obtain core β-FeOOH nanoparticles.

The resulting precipitate was separated from the solution by centrifuging, washed with deionized water (4 × 15 ml) and dried on a rotary evaporator.

b) Preparation of rod-shaped iron oxide nanoparticles based on a precursor 2 ml of a suspension of a precursor ([Fe] = 0.06 mol / l) was mixed with 40 μl of a solution of hydrazine hydrate (0.4 mol / l) and the pH of the resulting suspension was adjusted to 12 one molar solution of sodium hydroxide. After that, the reaction mass was transferred to a glass test tube, which was sealed and placed in a Monowave 300 microwave synthesis reactor.

The resulting suspension was irradiated at 200 W and 100 ° C for 30 seconds. Next, the reaction mass was cooled to room temperature using compressed air of the compressor for 2 minutes, and the irradiation procedure was carried out again. As a result, 4 cycles of irradiation were carried out according to the scheme described above. The resulting black-brown product was collected using a neodymium magnet, washed with deionized water (3 × 50 ml) and dispersed in water at neutral pH.

Example 3. Obtaining rod-shaped magnetite nanoparticles with a length of 26 nm.

Reagents and materials. Ferric (III) chloride (FeCl ₃ ; 97%), polyethyleneimine (PEI, branched, M _w ≈25000 g * mol ^-1 ) were purchased from Sigma-Aldrich and used without further purification. Deionized water was obtained using the MIlli-Q Water deionizer.

a) Preparation of the precursor (β-FeOOH rod-shaped nanoparticles).

Rod-shaped β-FeOOH nanoparticles were obtained by hydrolysis of an aqueous solution of FeCl ₃ ). To synthesize 26 nm nanoparticles of akagenit in a two-neck flask, 10 ml of iron (III) nitrate solution (2 mol / l) was mixed with 10 ml of hydrochloric acid solution with a concentration of 0.04 mol / l, after which 1.7 ml of PEL were added. Then 100 ml of deionized water, preheated to 80 ° C, was poured into the reaction mixture. The temperature of the reaction mixture was maintained at 80 ° C with vigorous stirring for 2 hours to obtain core β-FeOOH nanoparticles.

The resulting precipitate was separated from the solution by centrifuging, washed with deionized water (4 × 15 ml) and dried on a rotary evaporator.

(b) Preparation of rod-shaped iron oxide nanoparticles based on a precursor.

2 ml of the precursor suspension ([Fe] = 0.05 mol / l) was mixed with 40 μl of hydrazine hydrate solution (0.4 mol / l) and the pH of the resulting suspension was adjusted to 14.0 with a single molar ammonium hydroxide solution. After that, the reaction mass was transferred to a glass test tube, which was sealed and placed in a Monowave 300 microwave synthesis reactor.

The resulting suspension was irradiated at 200 W and 100 ° C for 30 seconds. Next, the reaction mass was cooled to room temperature, and the irradiation procedure was carried out again. As a result, 4 cycles of irradiation were carried out according to the scheme described above. The resulting black-brown product was collected using a neodymium magnet, washed with deionized water (3 × 50 ml) and dispersed in water at neutral pH. Microscopic studies carried out confirm the formation of rod-shaped nanoparticles with a length of 26 nm (Fig. 4).

Example 4. Carried out analogously to example 3, only as a reducing agent used hydrazinium chloride. Nanoparticles of rod-shaped form with a length of 26 nm and a narrow size distribution (± 6 nm) were obtained.

The results of testing the stability in aqueous solutions of the obtained nanoparticles are given in Table 3

Claims (6)

1. A method of producing magnetite rod-shaped nanoparticles, including preparing an aqueous suspension of a precursor, which is a rod of akagenite nanoparticles, in which a solution of a reducing agent, a compound from the group of hydrazines with two free electrons, is added in an amount that ensures reduction of iron Fe ³⁺ to Fe ²⁺ in alkaline conditions, characterized by pH = 10-14, when exposed to microwave radiation, after which the resulting solution is irradiated with microwave radiation at 200 ± 10 W and 90-100 ° C during e 30 ± 2 seconds, then the reaction mixture was cooled to room temperature, the resulting product was washed with deionized water to remove unreacted substances and dispersed in deionized water at neutral pH. 2. The method according to p. 1, characterized in that an aqueous suspension of the precursor is prepared with the content [Fe] = 0.06 ± 0.01 mol./l. 3. A method according to claim 1, characterized in that the irradiation procedure is repeated up to 4 times. 4. The method according to p. 1, characterized in that as compounds of the group of hydrazines use hydrazine hydrate, hydrosinium chloride, hydrosynium sulfate. 5. The method according to p. 1, characterized in that the solution of the reducing agent is prepared with a concentration of 0.4 ± 0.1 mol./L. 6. The method according to claim 1, characterized in that 10 parts by volume of the suspension of akagenit take 1 ± 0.5 parts of the solution of reducing agent.

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