RU2426692C1 - Method to produce nanoparticles of silica - Google Patents

Abstract

FIELD: nanotechnologies.

SUBSTANCE: invention relates to production of silica nanoparticles. The method includes production of silica nanosol by hydrolysis of tetraethoxysilane (TEOS) with the ratio of TEOS: ethanol: water, acidified with HC1 up to pH 1.5-2,=1:5:6 and nanosol maturing. Nanosol maturing is carried out for two hours at the temperature of 40-50°C. The mature alcohol is dissolved with water at the ratio of 1:8, additing anion-exchange resin AB 17/2 at the weight ratio of nanosol: resin=10:(2.8-3). It is mixed for 15-20 minutes, and nanosol is filtered from granules of anion-exchange resin.

EFFECT: invention makes it possible to produce nanosol with pH 6,5-7, resistant to aggregation of nanoparticles and coagulation, when adding biological buffer solutions, solutions of pilolysine or solutions of oligonucleotides.

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Description

Technical field

The invention relates to nanotechnology, namely, to obtain a sol of silica nanoparticles intended for medical use, in particular, as a transporter of oligonucleotides to affected cells in the form of nanoparticle-oligonucleotide complexes.

State of the art

The unique ability to treat gene diseases (tumors and infections of a viral nature) opens up the ability of oligonucleotides to carry out the correction of mutations in damaged genes. However, there is a problem in the delivery of oligonucleotides to a damaged gene. This problem can be solved, in particular, by using a nanoparticle – oligonucleotide complex capable of penetrating mammalian cells. Derivatives of oligonucleotides addressed to the structure of the genome are known to be able to immobilize on TiO ₂ and SiO ₂ nanoparticles. For example, in (Paunesku, T. Biology of TiO ₂ - oligonucleotide nanocomposites / T. Paunesku, T. Rajh, G. Wiederrecht, J. Maser, S. Vogt, N. Stojicevic, M. Protic, B. Lai , J. Oryhon, M. Thumauer, G. Woloschak // Nature materials. - 2003. - V.2. - P.343-345) the unique ability of the complex was discovered: a TiO ₂ nanoparticle - DNA oligonucleotide to penetrate mammalian cells.

The unique properties of TiO ₂ and SiO ₂ nanoparticles are due to the nanoscale effect. For the effective penetration of nanoparticles into cells, the required nanoparticle size should be 4-5 nm.

A known method of synthesis of silica nanoparticles (SiO ₂ ) described in patent No. 2370310, publ. October 20, 2009, consisting in the fact that in the preparation of the silica sol, the molar ratios of the reagents were used: tetraethoxysilane (TEOS): water, acidified with HCl to pH 1.5-2,: ethanol = 1: 6: 5.

However, the water-ethanol nanosol of silica nanoparticles with a size of 5-8 nm obtained by this method has a high HCl content with a pH of 1.5-2 nanosol and an ethanol content of 30 vol. %, which prevents its direct use for medical purposes. In addition, in acidic media, silica nanoparticles quickly aggregate to form a spatial gel network. Therefore, to maintain the coagulation stability of the nanosol, a surfactant, cetyltrimethylammonium chloride, is introduced into it, which is also undesirable when using the sol for medical purposes.

The objective of the invention is to develop a method for producing a stable nanosol of silica particles (SiO ₂ ) with a size of 4-5 nm with a pH of 6.5-7, suitable for creating a complex: SiO ₂ nanoparticle - DNA oligonucleotide and its further use for therapeutic purposes.

Disclosure of invention

The essence of the invention lies in the fact that in the known method for producing silica nanosol, which includes obtaining silica nanosol with pH 1.5-2 by hydrolysis of tetraethoxysilane (TEOS) in a mixture of TEOS: ethanol: water, acidified with HCl to pH 1.5-2, = 1: 5: 6, respectively, followed by exposure to the maturation of the nanosol, the maturation time of the nanosol is two hours at a temperature of 40-50 ° C. Ripe nanosol with a nanoparticle size of 4-5 nm for stabilization is diluted with water in a ratio of 1: 8, which prevents the aggregation of nanoparticles, while the pH of the nanosol rises to 3-3.5. Then, AB 17/2 anion-exchange resin is introduced into the nanosol in the weight ratio of nanosol: resin equal to 10: (2.8-3), stirred for 15-20 minutes and the resin granules are filtered off from the nanosol.

This achieves the following technical result:

- get a clear, colorless silica nanosol with a pH of 6.5-7;

- due to the high degree of dilution with a neutral charge on the surface of the particles, a nanosol is obtained that is resistant to aggregation of nanoparticles and coagulation of the nanosol for at least 48-72 hours;

- get nanosol containing ethanol in an amount of not more than 2-2.5%;

- the obtained nanosol is resistant to aggregation of nanoparticles and coagulation when added to it: a) biological buffer solutions; b) solutions of pililizin protein; c) solutions of oligonucleotides;

- the obtained nanosol, when used for medical purposes, can be diluted to a concentration of 1: 100, which further increases its resistance to particle aggregation and coagulation.

Justification of the introduced features

To obtain a neutral (pH 6.5-7) silica nanosol with a particle size of 4-5 nm, acidic silica nanosols obtained by hydrolysis of tetraethoxysilane in a solution of ethanol and an aqueous HCl solution (with a pH of a mixture of 1.5-2) are used for the first time, followed by maturation which are then diluted with water without stabilization of the surfactant and neutralized to a pH of 6.5-7 by treatment with anion exchange resin AB 17/2.

In preparation for medical use, the sol is additionally diluted to the desired concentration and buffer solutions and oligonucleotide solutions are introduced into it.

Thus, the claimed combination of features makes it possible to exclude the high acidity of the sol and such undesirable processes as aggregation of nanoparticles and the formation of a spatial gel network, and due to this, to obtain colloidal solutions (nanosols) of silica nanoparticles with a size of 4-5 nm compatible with biological buffer solution, solutions pilolysin, a solution of oligonucleotides. Nanoparticles from such a nanosol can penetrate the cell membrane and can be used to solve the problem of transporting oligonucleotides into the cell in the form of SiO ₂ nanoparticle – oligonucleotide complexes or SiO ₂ –pilolysin-oligonucleotide nanoparticle complexes.

An example of the method

Nanosol is prepared from a mixture of reagents: tetraethoxysilane (TEOS): water, acidified with HCl to pH 1.5-2,: ethanol taken in molar ratios: 1: 5: 6, respectively. To ripen the nanosol of silica nanoparticles to a size of 4-5 nm, the mixture of reagents is incubated for two hours at a temperature of 40-50 ° C. In this case, the initial volume of the mixture is reduced by one fourth, mainly due to the evaporation of ethanol. Next, the ripened nanosol of nanoparticles with pH = 1.5-2 is diluted with water in a ratio of 1: 8, as a result of which the pH of the nanosol increases to 3.5. Granular anion exchange resin AB 17/2 is introduced into diluted nanosol to completely neutralize HCl in a weight ratio of nanosol: resin = 10: (2.8-3), stirred for 15-20 minutes, which is sufficient for the HCl neutralization process to proceed, the granules are filtered off resin using a paper filter and get nanosol of particles of SiO ₂ with a pH of 6.5-7 and an ethanol content of 2-2.5 vol.%

The obtained silica nanosol is resistant to coagulation and gelation for 10-15 days under normal conditions. When electrolytes, a solution of oligonucleotides and a complex of pilolysin - oligonucleotides are introduced into a sol of a biological buffer, gelation does not coagulate.

Claims (1)

A method of producing silica nanoparticles, including the preparation of silica nanosol by hydrolysis of tetraethoxysilane (TEOS) at a ratio of TEOS: ethanol: water, acidified with HCl to pH 1.5-2, = 1: 5: 6, and maturation of nanosol, characterized in that the maturation of nanosol carried out for two hours at a temperature of 40-50 ° C, the ripened nanosol is diluted with water in a ratio of 1: 8, an anion exchange resin AB 17/2 is introduced into it in a weight ratio of nanosol: resin = 10: (2.8-3), mixed for 15-20 minutes and the nanosol is filtered off from the granules of the anion exchange resin.