ИСТИНА

The functional materials based on nanoparticles (NPs) of noble metals (Me) have attracted much attention of researchers due to their unique physicochemical, biological, optical and catalytic properties. It is shown that maleic acid copolymers (CMA) are effective stabilizers of NPs of noble metals (silver and gold). These copolymers have the following advantages as compared to other polymer stabilizers of NPs: biocompatibility and biodegradability, low cytotoxicity, commercial availability, regular chemical structure of polymer chain, solubility in water in a wide range of pH values, possibility to vary the hydrophobic-hydrophilic balance of CMA, and easy chemical modification of dicarboxylic acid residues. The last property makes them prospective for address delivery of NPs. In the present study, we have studied in detail the structure formation in the solutions of CMA with ethylene (EMA) or N-vinylpyrrolidone (VMA), the process of formation of CMA-Me+ complexes, and the structure of CMA/Me0 sols and nanocomposites. The preparation of NPs of noble metals stabilized by CMA consists of 2 stages: the formation of polymer salt of metal and the borohydride reduction of this salt. It is shown by dynamic and static light scattering that diluted solutions of CMA, CMA-Me+ salt and CMA/Me0 hydrosols were partially aggregated. The aggregates in solutions of CMA are micelles of core-polyelectrolyte shell type. The pH range of micellization in CMA solutions depends of comonomer hydrophobosity. The main driving forces of aggregation are H-bonding and hydrophobic interactions. We carried out molecular dynamics computer simulation of EMA conformation behavior in diluted solution upon solvent quality worsening, which corroborated formation of hydrophobic core – hydrophilic shell micelles and their partial aggregation. The complexation of Me+ ions takes place inside individual macromolecules as well as inside polymer aggregates that results in a formation of unimolecular core-shell micelles and micellar clusters having a polyelectrolyte shell and Me NPs embedded in a polymer network as a core1. The polyelectrolyte character of micelles and micellar clusters was exhibited in the decrease of both hydrodynamic radii with the ionic strength increasing. In contrast to CMA/Ag0 sols CMA/Au0 sols have broad hydrodynamic radius distribution with 2 semidetached maxima. According to TEM data NPs of noble metals stabilized by CMA have size of 1.5–3.5 nm. The obtained NPs of noble metal stabilized by CMA can be stored as dried powder, and after redissolution the micellar structure of initial hydrosol was reproduced. CMA/Ag0 hydrosols and nanocomposites could be used in practice as antiseptic agents. Antifungal activity of sols against plant pathogen F. Oxisporum has been demonstrated1. The efficiency of CMA/Au0 sols application as colloidal catalysts of the aerobic oxidation of glucose was shown2.