Method of making structures on basis of semiconductor monocrystals and organic molecules. RU patent 2504430.

FIELD: process engineering.

SUBSTANCE: invention relates to production structures based on semiconductor nanocrystals and organic molecules to be used as micro fluid elements ion optoelectronic devices. Proposed method consists in implanting nanocrystals and organic molecules in membrane track pores. Nanocrystals are implanted in track pore wall layer while organic molecules are bonded with modified or unmodified carboxyl groups on track membrane track pore inner surface. Or, molecules are bonded into complex with nanocrystals implanted in track membranes owing to impregnation of membranes with solutions of nanocrystals and organic molecules under normal conditions.

EFFECT: simplified process, higher capacity of produced membranes in polymer track membranes.

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The invention relates to the pharmaceutical, food, biomedical and other industries and can be used as a microfluidic elements in optoelectronic devices.

Semiconductor nanocrystals are a class of nano-size objects and crystal structure of different shape (spherical, , asymmetric)made from semiconductors germanium and silicon) and a variety of semiconductor compounds: AIBVII, AIIBVI, AIIIBV, AIVBVI. Under the organic molecules are defined as any organic molecules, known and unknown today that are able to communicate in complex with semiconductor nanocrystals or molecules solubilizer on their surface, or communicate with carboxyl unmodified or modified groups on the inner surface of the pores of track membranes.

There is a method of creating structures based on semiconductor nanocrystals (NC) and organic and/or inorganic compounds in porous polymer materials through serial or joint implementation of the components in the pores of the «how to create and use of porous materials with embedded nanoparticles» (US Patent # US 2009/0169861 A1, application 11/385,504, date of publication, 02.07.2009, the priority date 20.03.2006) [1]. Such structures can be used in sensors, medical diagnostics, optoelectronics, etc. The disadvantage of this method is that performance-based devices, polymer structures, evenly distributed throughout the volume, decreases due to diffusion of the analyte through a polymer that for a number of substances can be impermeable.

There is a method to create multilayer porous membranes with organic molecules (OHMS). In this case the inner surface of through pores modified several gold. After modification gold is adsorption of organic molecules, which are used for selective ion exchange and detection of ions. Action membranes based on the interaction of ions dissolved in the liquid flowing through the membrane, with the substances adsorbed on the inner surface of the pores of «Controlled ion-exchange membranes» (US Patent US 6,468,657, IPC B32B 5/16, A61L 5/103, G01N 33/53, the application 09/206,084, date of publication 22.10.2002, priority 04.12.1998) [2]. In this case there is no need to substances diffusion in polymer. The shortcomings described in this patent the method are rather complicated technology of obtaining of monolayers gold on the inside surface of the track and then a necessary condition: the ability to self-organization of organic molecules on the modified gold inner surface of the pores. (Y. Gromov, A.V. Savelyev Creation of a composite material on the basis of semiconductor quantum dots in track membranes. Book of abstracts of young scientists conference, issue 2, St. Petersburg, p. 340 2011-341) [3] demonstrated the possibility of creating nanostructures on the basis of semiconductor quantum dots in track membranes with hydrophobic . The disadvantage of the proposed method is that to create the structures in this case, the molecule must possess a certain and be able to communicate in complex quantum dots.

Closest to the claimed invention and adopted as a prototype «Way to create structures in porous membranes» (US Patent US 2006/0263884, IPC G01N 33/00, 23.11.2006 date of publication, date of priority 21.01.2004) [4]. According to the description to the patent for the creation of structures on the basis of track membranes are used carboxyl group on the inner surface of the pores. Perhaps covalent or linking carboxylic groups with various substances (molecules, combination of molecules, particles, with semiconductor nanocrystals), which allows to manage the permeability of the membrane, quantitatively commit changes to a solution by detecting changes in the physical or chemical properties of ligands that are sensitive to certain environmental changes, have a catalytic impact on the solutions. The prototype has a few drawbacks. In creating the structures in track membranes involved only a carboxyl group on the inner surface of the track then. This leads to the fact that the number of structures on the inner surface of the pores fundamentally limited number of carboxyl groups on a given surface. When you create a microfluidic devices based on the proposed prototype modification of carboxylic groups, which are located on the inside surface of the pores, the selection of substances for modification of the inner surface is limited and the ability of these substances to chemical interaction either with carboxyl groups, or chemically modified carboxyl groups. Multi-layer modification of the inner surface of the pores may lead to a considerable reduction of the free volume of pores and, accordingly, to a noticeable decrease of the capacity of such membranes.

Technical task to be solved by the invention is increasing the number of structures in polymer track membranes, increasing the capacity of membranes with embedded structures and simplify the process of creating structures.

The task is achieved by the fact that semiconductor nanocrystals implement by soaking parietal layer of track membranes pores solution of these nanocrystals, and organic molecules associated either with semiconductor nanocrystals, or with carboxyl groups on the inner surface of track-etched membranes pores by soaking membranes with embedded semiconductor nanocrystals solution of these molecules under normal conditions. The carboxyl group in case of necessity can be chemically modified.

Essence of the invention lies in the fact that the structure consisting of semiconductor nanocrystals and organic molecules embedded in the surface layer of the track then, polymer membranes, track pores remain free to fluid current through the sample. For the implementation of nanocrystals in polymer track membranes do not require any chemical groups on the inner surface of the track then, or additional chemical modifications.

The proposed method has the following advantages. Introduction of nanocrystals in the wall surface layer of the inner surface of the pores occurs irrespective of the number of carboxyl groups on the surface of the track then, and does not require any chemical modification of the surface of the track then. This eliminates the need to resolve the issue of chemical conjugation of nanocrystals with carboxyl groups. The transition from the inner surface of the track then to a volume layer tracking pores allows to substantially increase the number of structures compared with the method of modification of track membranes, proposed in the prototype. The use of the parietal layer of tracking pores allows not only to increase the number of structures in the membrane, but also, unlike the original, allows to maintain the free volume of the track then. It conserves bandwidth membranes with structures at the level of bandwidth empty membranes and, consequently, improve throughput membrane structures, formed by the proposed method in comparison with the method proposed in the prototype.

Stages of implementation in membrane semiconductor nanocrystals and organic molecules can be held at different times independently. On the basis of one element (the membrane with nanocrystals embedded) you can create devices with different functionality and multi-function devices. Progressive downloading components in membrane allows you to create complexes of elements essentially insoluble in a solvent. Nanocrystals embedded in the surface layers of the tracking long isolated polymer, which prevents the possibility of contamination of the working solution of heavy ions, which may occur during the degradation of .

The essence of the proposed invention is illustrated by figures 1-7 are:

Fig 1. - Drawing of polymeric membrane with semiconductor nanocrystals embedded in the surface layers of the tracking of the pores.

figure 2. - Schematic depiction of the track membrane structures in the surface layer of the tracking far: NC embedded in the surface layer of the track then, OHM adsorbed on the surface of nanocrystals;

figure 3. - Schematic depiction of the track membrane structures: NC embedded in the surface layer of the track then, OHM adsorbed on the inner surface of the pores due to the interaction with modified or unmodified carboxyl groups;

figure 4 - the absorption Spectra of (a) and luminescence (b) samples of track membranes with the structures based on semiconductor hydrophobic nanocrystals CdSe/ZnS and molecules PAIRS of azo dye environment, received in the result of the consecutive soaking sample solution nanocrystals and solutions of PAIRS of molecules of different concentration: 1 - R-RA PAIRS =0 mol/liter; 2 - R-RA PAIRS =2·10 -7 mol/liter; 3 - R-RA PAIRS =2·10 -5 mol/litre, 4 - R-RA PAIRS =2·10 -3 mol/liter;

figure 5 - absorption Spectra (a, b) and luminescence (b, g) of track membranes with the structures based on semiconductor nanocrystals embedded in the wall surface layer tracking pores and organic molecules attached to the unmodified (a, b) and the modified carboxyl groups (a, g): 1 - R-RA =0 mol/liter; 2 - R-RA =10 -7 mol/liter; 3 - R-RA =10 -5 mol/litre, 4 - R-RA =10 -3 mol/liter; 5-8 structures based on semiconductor nanocrystals forms of CdSe/ZnS and molecules of chlorine 6: 5 - R-RA 6 =0 mol/liter; 6 - R-RA 6 =10 -7 mol/liter; 7 - p-6 =10 -5 mol/liter; 8 - p 6 =10 -5 mol/liter 6 - Consistent implementation of semiconductor nanocrystals and organic molecules in the polymer track membranes: 1 - sample of the track membrane; 2 - the solution of the NK; 3 - a sample of the track membrane with embedded NC; 3 - solution OHM;

To demonstrate the workability of the proposed method, the creation of structures based on hydrophobic semiconductor nanocrystals and organic molecules in track membranes have been successively introduced hydrophobic spherical semiconductor nanocrystals CdSe/ZnS with core diameter 2.5 nm, and hydrophilic molecules 4-(2-)-resorcinol (PAR).

At the first stage, a sample of impregnated with a solution of toluene NC, synthesized in accordance with the well-known procedure (A. Sukhanova, A.V. Baranov, et al. Controlled Self-Assembly of Nanocrystals into Polycrystalline Fluorescent Dendrites with Energy-Transfer Properties. Angew. Chemie Int. Ed. 2006. V.45. №13. P.2048-2052) [5]. Article (A.O. Orlova, Yu. A. Gromova, A.V. Savelyeva, VG Maslov, M.V. Artemyev, A. Prudnikau, A.V. Fedorov and A V Baranov. Track membranes with embedded semiconductor nanocrystals: structural and optical examinations. Nanotechnology. 22 (2011) 455201 (7pp)) [6], it was shown that as a result of the soaking of samples of polymer track membranes solutions nanocrystals there is the introduction of NK in the parietal layers track then. The optical properties of nanocrystals embedded in track membranes differ little from the optical properties of NDT data in solutions. This suggests that nanocrystals in track membranes do not form and are quasi-isolated state.

Molecule PAIRS is hydrophilic luminosity . COUPLES forms a chelate complexes with a number of metals, including Zn ions (V.M. Ivanov Heterocyclic nitrogen-containing azo compounds - M: Nauka, 1982. - .270.) [7]. Therefore, PAIRS of molecules are capable of forming coordination complexes with surface Zn ions shell nanocrystals CdSe/ZnS. At the second stage of creating the structures track membrane with embedded nanocrystals is the aqueous solution of PAIRS.

Of the absorption spectra of the samples membranes presented at Fig.4, it appears that increasing concentrations of PAIRS of molecules in solution, which saturated samples, results in increase of concentration of molecules in the sample. The increase in the concentration of molecules of STEAM in the samples of the track membrane is accompanied by effective quenching of luminescence of nanocrystals on Fig.4, which is due to nonradiative energy transfer from NC to molecules PAIRS. Since PAIRS of molecules do not interact nor with carboxyl groups, nor with the material membranes, increasing the concentration of molecules of STEAM in the samples clearly indicates the formation of complexes of quantum dots with molecules of STEAM in the result of the coordination of molecules on the surface Zn ions. Joining PAIRS of molecules to the surface of the CT leads to the suppression of a luminescence on the mechanism of nonradiative energy transfer, and in the presence of the metal ion, for which the constant of complexing higher than for complex PAIRS/Zn causes dissociation of the complex and there is a flare-up of luminescence . On this principle, it is possible to build sensors metal ions and pH environment (RF Patent №2419646, IPC G01N 21/62, date of publication 20.03.2011, the priority date of 19.11.2008) [8], (Application of the Russian Federation №2011104310, IPC G01N 21/62, the priority date of 07.02.2011) [9]. The analysis of the absorption spectra presented at Fig.4, showed that the number of structures NC/OM four times the number of structures that form on the surface of the track pores of the membrane. This suggests that the use of the parietal layer of the track then, instead of their surface can significantly increase the number of structures in the membrane.

The average speed of distilled water streak through pores in the membrane-embedded-based structures nanocrystals CdSe/ZnS and PAIRS of molecules under normal conditions and the difference in pressure 0.39 PA (created water pillar) is 0.05±0.008 Ml/min·cm2 , which is comparable with the speed of passage of distilled water through the empty membrane under the same conditions (0.06±0.01 Ml/min·cm2 ). This indicates that the free volume of the track then and, accordingly, to increase the bandwidth of track membranes with the structures of the TC/OM generated by the proposed method in comparison with the method described in the prototype.

Thus, the possibility of the creation of structures based on semiconductor nanocrystals and organic molecules of various in layer of track membranes pores for the case when the OM associated with the surface of the NC.

Example 2.

To demonstrate the workability of the proposed us ways to create structures on the basis of NC, embedded in the wall layers track long and OM associated with carboxyl groups, membranes were consistently impregnated with a solution of hydrophobic nanocrystals of the spherical shape of CdSe/ZnS and solutions hydrophilic molecules Tetra(R-trimetilamino) () of different concentration. This connection has four positively charged amino group. Therefore, when it is saturated samples membranes with water solution happens adsorption of molecules on the inner surface of the track then, due to the electrostatic interaction with negatively charged carboxyl groups, located on the walls of the track membrane pores. Absorption spectra of (a) and luminescence (b) samples containing the structure of CdSe/ZnS CT , are presented in figure 5.

Under the modification of carboxylic groups in this case means any procedure chemical modification using standard molecules , for example, 1-ethyl-3-(3-) Carbo- hydrochloride (EDAC) (Greg T. Hermanson Bioconjugate Techniques. Academic Press, 1996-785p.) [10].

To demonstrate the possibilities of the use of chemical modification of carboxylic groups to create structures NC/OM using EDAC was modification of carboxyl groups, which allows to receive a positive charge on the walls of the pores of the membrane. Then in the membrane were introduced semiconductor nanocrystals CdSe/ZnS form (the ratio of the diameter to length is 1:8). Membrane-embedded NC saturated by water solutions of Chlorin E6 (6) of different concentrations. This connection has three negatively charged carboxylic groups, therefore the adsorption of molecules on the inner surface of the track then, due to the electrostatic interaction with the positively charged amino groups, resulting from the modification of carboxylic groups in the membrane. The absorption spectra of the (in) and luminescence (g) of the membranes that contain patterns of CdSe/ZnS NC - chlorin E6, are presented in figure 5.

Of the spectra presented in figure 5, it is seen that the increase in the concentration of porphyrin molecules and chlorine in the solution, which saturated samples, results in increase of concentration of molecules in the sample. In these examples in the samples of track membranes, impregnated consistently solutions nanocrystals and molecules or 6, binding OHM with the tax code does not occur. Therefore, at a constant concentration of nanocrystals in the near-wall layers track then samples membranes decreases the intensity of the luminescence of NK, which correlates with the increase of the concentration of molecules in samples indicates interaction of nanocrystals with the molecules, i.e. the dipole-dipole energy transfer photoexcitation from NC to porphyrin molecules.

Molecules and chlorin E6 characterized by efficient generation of singlet oxygen. Therefore, the polymer track membranes with hybrid structures based on semiconductor nanocrystals and molecules sensitizer, are experiencing the efficient transfer of energy of photoexcitation of NK to the molecules that can be used as the basis of microfluidic devices to effectively generate singlet oxygen"Photosensitisers in medicine, Environment, and Security". T. Nyokong, V. Ahsen, Eds. Part II, Springer-Verlag. 1st Edition 2011, 699 p.) [11]. The rate of passage of distillate through the samples of membranes with structures NC/ and NK/6 under normal conditions and the difference in pressure 0.39 PA (created water pillar) was 0.045±0.006 and 0.05±0.005 Ml/min, cm, respectively. These values are close to the values of bandwidth empty membrane (0.06±0.01 Ml/min·cm2 ). This shows that, as in the case of binding OM NC, discussed in example 1, in the membranes of these structures throughput higher than in the membranes of the structures discussed in the prototype.

The proposed method of creating structures in polymer track membranes can be implemented without the use of additional devices. As illustrated in Figure 6, for introduction into polymer track membranes semiconductor nanocrystals and organic molecules consistently enough sample diaphragm 1 place in the solution of nanocrystals 2. After that, the sample with embedded MK 3 is placed in a solution of organic molecules 4. In case, when the introduction of organic molecules in track membranes pores occurs through the interaction of MD with carboxyl groups on the inner surface of the track then, order of introduction in samples membranes NC and OM can be inverted.

In that case, when the introduction of OM in membrane occurs as a result of the formation of the complexes MK/OM structures in polymer track membranes can be created with the introduction of these complexes MK/OM created in the solution. This situation is illustrated in Fig.7.

Thus, the invention is characterized by the increasing number of structures embedded in a polymer track membranes, improved, compared with the reference bandwidth membranes with structures and more simple realization of ways to create structures NC/OM in membranes. The use of the alleged invention of the parietal layer of the inner surface of the track then to create structures NC/OM to not create on the surface of pores multilayer coatings and thus, unlike the original, not to reduce the initial volume of the track then. This allows to increase the throughput of samples of polymer track membranes with the structures of the TC/OM compared with the prototype in which the internal surface of the track then modified multilayer coatings. At the same time to introduce semiconductor nanocrystals not require any modification of the inner surface of the track then, nor any groups on the inside of the track membrane pores.

Sources of information

1. US patent # US 2009/0169861 A1, application 11/385,504, date of publication, 02.07.2009, the priority date 20.03.2006.

2. US patent US 6,468,657, IPC B32B 5/16, A61L 5/103, G01N 33/53, the application 09/206,084, date of publication 22.10.2002, the priority date of 04.12.1998.

4. US patent US 2006/0263884, IPC G01N 33/00, 23.11.2006 date of publication, date of priority 21.01.2004.

5. A. Sukhanova, A.V. Baranov, et al. Controlled Self-Assembly of Nanocrystals into Polycrystalline Fluorescent Dendrites with Energy-Transfer Properties. Angew. Chemie Int. Ed. 2006. V.45. №13. P.2048-2052.

6. A.O. Orlova, Yu.A. Gromova, A.V. Savelyeva, VG Maslov, M.V. Artemyev, A. Prudnikau, A.V. Fedorov and A V Baranov. Track membranes with embedded semiconductor nanocrystals: structural and optical examinations. Nanotechnology. 22 (2011) 455201 (7pp).

7. Ivanov, B.M. Heterocyclic nitrogen-containing azo compounds - Moscow: Nauka, 1982. - .270.

8. Patent of Russian Federation №2419646, IPC G01N 21/62, date of publication 20.03.2011, the priority date of 19.11.2008.

9. Application of the Russian Federation №2011104310, IPC G01N 21/62, the priority date of 07.02.2011.

10. Greg T. Hermanson Bioconjugate Techniques. Academic Press, 1996, 785 p.

11. "Photosensitisers in medicine, Environment, and Security". Nyokong, Tebello; Ahsen, Vefa (Eds.), 2012, 699 p.

Way to create structures based on semiconductor nanocrystals and organic molecules, based on implementation of semiconductor nanocrystals and organic molecules in track membranes pores, wherein the semiconductor nanocrystals implement by soaking parietal layer of track membranes pores solution of these nanocrystals, and organic molecules associated either with semiconductor nanocrystals, either modified or unmodified carboxyl groups on the inner surface of track-etched membranes pores by soaking membranes with embedded semiconductor nanocrystals solutions of these molecules under normal conditions.