RU2433084C1 - Method to produce modified optical chemosensory films based on silica - Google Patents

Abstract

FIELD: nanotechnologies.

SUBSTANCE: invention relates to nanotechnologies, in particular, to the method to produce optical structured chemosensory films based on silica particles with size of 5-8 nm with modified surface. The method includes production of a nanosol of spherical silica particles with size of 5-8 nm from the following mixture: tetraethoxysilane : water acidified with HCl to pH of 1.5-2, : ethanol = 1:6:5, ethanol maturing at 60-70°C for 2-4 hours, stabilisation of the nanosol by cetyltrimethylammonium chloride at mole ratio of cetyltrimethylammonium chloride : nanosol = 0.25, application of the nanosol at the substrate and production of the chemosensory film, at the same time to modify the silica nanoparticles a solution of the colloid silver-fluorescein complex is used, made by mixing 1% of fluorescein solution in ethanol, and 0.08% of colloid silver solution in the volume ratio of solutions 1:1, which is introduced into the matured and stabilised nanosol at the ratio of volumes of nanosol : complex solution equal to 3:2.

EFFECT: invention makes it possible to increase intensity of chemosensory film photoluminescence 2-2,5 times.

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Description

Technical field

The invention relates to nanotechnology, in particular to the production of structured optical chemosensor films based on silica nanoparticles (SiO ₂ ) of size 5-8 nm with a surface modified by a complex: colloidal silver - an organic dye (receptor), in particular fluorescein.

State of the art

The creation of highly sensitive optical chemical and biological sensor film materials is caused by the urgent need for real-time remote monitoring of industrial wastes, water and air for analyzed harmful substances (analytes) using miniature devices based on optical effects that occur during analyte adsorption. In particular, a method is known for producing chemosensor films based on silica nanoparticles modified with an organic dye — an analyte receptor, fluorescein (RU No. 2370310, C1, IPC: B01J 13/00, publ. 20.10.2009) / 1 /.

A disadvantage of the known silica-based optical chemosensor films is that the receptor is a dye located mainly on the surface of the film, and the sensitivity and, accordingly, photoluminescence (PL) intensity of the chemosensor film is insufficient. This is due to the fact that the porosity of these films is small (of the order of 1-2 nm), and for this reason they are called mesoporous.

The search for fundamentally new solutions to increase the PL intensity and increase the sensitivity of chemosensor films made us pay attention to the possibility of using nanolaser radiation for this purpose, which arises as a result of silver plasma resonance upon short-wave excitation and transfer of this additional energy to the dye (spacer effect) (Mark I. Stockman. // Nature Publishing Group. 2008. Vol.2. June. P.327-329) / 2 /, (MANoginov, G. Zhu, AM Belgrave, R. Bakker, VMShalaev, EENarimanov, S. Stout , E. Hers // Nature. Letters. Vol. 460. August. P. 1110-1112) / 3 /.

Disclosure of invention

The objective of the invention is to develop a method for producing chemosensor films, which in a solid-state material based on silica nanoparticles provide a significantly higher PL intensity and have a higher sensitivity to analyte compared to dye-modified silica nanoparticles.

The technical result consists in increasing the PL intensity of a chemosensor film based on silica nanoparticles (mesoporous film) and its sensitivity to analyte.

This problem is achieved by the fact that in the method for producing modified optical chemosensor films based on silica (RU No. 2370310), including the production of nanosol of spherical silica particles of 5-8 nm in size from a mixture: tetraethoxysilane: water, acidified with HCl to pH 1.5-2, : ethanol = 1: 6: 5, maturation of nanosol at 60-70 ° C for 2-4 hours, stabilization of cetyltrimethylammonium nanosol chloride, deposition of nanosol on a substrate and preparation of a chemosensor film according to the invention, a complex solution is used to modify silica nanoparticles and colloidal silver is an organic dye, in particular fluorescein, obtained by mixing a 1% solution of fluorescein in ethanol and a 0.08% solution of colloidal silver, in a volume ratio of 1: 1 solutions, and the resulting solution of the colloidal silver-fluorescein complex is introduced into a ripened and stabilized nanosol.

Wherein

- when stabilizing the cetyltrimethylammonium nanosol chloride, use the molar ratio of cetyltrimethylammonium chloride: nanosol equal to 0.25;

- a solution of the complex colloidal silver - fluorescein is driven with a volume ratio of nanosol: complex solution equal to 3: 2;

- as an organic dye, a dye is used that forms a complex with silver nanoparticles, in particular fluorescein.

Justification of the introduced features.

To modify the surface of silica in nanosol and the subsequent production of a solid chemosensor film, the complex was first used: a colloidal silver-organic dye, in particular fluorescein, in which the plasma resonance energy of silver is transferred to the dye as a result of external short-wave (360 nm) excitation (spacer effect). The generation mechanism with the participation of the spacer effect [3] is described for particles in a liquid medium, but its manifestation in a solid-state material (mesoporous silica) is noted for the first time. As a result, the PL intensity of the mesoporous sensor film containing the colloidal silver – dye complex is 2–2.5 times higher than the PL intensity of the film containing only the dye.

The drawing shows the result of an independent examination of the photoluminescence spectra of optical chemosensor films performed at the Institute of Automation and Electrometry of the SB RAS:

a) based on mesoporous silica modified with a colloidal silver-fluorescein complex;

b) based on mesoporous silica modified with fluorescein.

An example of the method

Silica nanosol with a SiO2 nanoparticle size _of 5-8 nm is prepared at a molar ratio of the tetraethoxysilane: water mixture, acidified with HCl to a pH of 1.5-2,: ethanol = 1: 6: 5. To ripen the nanosol, the reagent mixture is kept for three hours at a temperature of 60-70 ° C. Then, CTMA, Cl with a molar ratio of CTMA, Cl: SiO ₂ = 0.25 are introduced into the sol. The finished nanosol is diluted with ethanol in a sol: ethanol ratio of 3: 2. Separately, a solution of the complex is prepared: colloidal silver - fluorescein. For this, a 0.08% aqueous solution of colloidal silver is added to a 1% solution of fluorescein in ethanol. After mixing, a solution of the complex is obtained: silver is a dye with spontaneous yellow-green fluorescence. The solution of the complex is introduced into nanosol in the ratio sol: complex equal to 3: 2. After stirring for 10-15 minutes, the freshly prepared complex-modified nanosol is ready for the manufacture of a sensor film. For this, the nanosol is applied to the surface of the substrate by the drop method or by immersion of the substrate in nanosol followed by drying.

Given the good wettability of the glass with nanosol, chemosensor films are obtained on the glass surface by the droplet method with the formation of a transparent uniformly colored film after 15-20 minutes, after the dripping drop has dried. The photoluminescence spectra of optical chemosensor films shown in the drawing show that the PL intensity during the modification of mesoporous silica with the colloidal silver-organic dye complex (a) is at least 2-2.5 times higher than the PL intensity when modifying mesoporous silica with only one dye ( b)

Claims (3)

1. A method for producing modified optical silica-based chemosensor films, comprising producing a nanosol of spherical silica particles of 5-8 nm in size from a mixture: tetraethoxysilane: water, acidified with HCl to pH 1.5-2 ,: ethanol = 1: 6: 5, maturation nanosol at 60-70 ° C for 2-4 hours, stabilization of cetyltrimethylammonium nanosol chloride, deposition of nanosol on a substrate and the preparation of a chemosensor film, characterized in that for the modification of silica nanoparticles use a solution of the colloidal silver - fluorescein complex obtained by mixing iem 1% solution of fluorescein in ethanol and 0.08% solution of colloidal silver solution in a volume ratio of the solutions, combined 1: 1 and the solution of the complex colloidal silver - fluorescein administered in matured and stabilized nanozol. 2. The method according to claim 1, characterized in that when stabilizing the cetyltrimethylammonium chloride nanosol chloride, a molar ratio of cetyltrimethylammonium chloride: nanosol equal to 0.25 is used. 3. The method according to claim 1, characterized in that the solution of the colloidal silver-fluorescein complex is introduced into nanosol with a volume ratio of nanosol: complex solution equal to 3: 2.

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