Water-dispersible nanocomposites of fullerene C60 and polymer-stabilized silver nanoparticles: preparation, physico-chemical properties, and antifungal activity

Abstract

A simple method of obtaining composites based on fullerene and silver nanoparticles (AgNPs) has been proposed. Non-covalent water-dispersible composites were prepared by mixing a water solution of polymer-stabilized AgNPs and a solution of pristine fullerene C₆₀ in N-methylpyrrolidone (NMP), followed by exhaustive dialysis against water. Alternating copolymers of dicarboxylic acid were used as stabilizing copolymers in the complexes of AgNPs: poly(styrene-alt-maleic acid) – SM, poly(N-vinyl-2-pyrrolidone-alt-maleic acid) – VM or poly(ethylene-alt-maleic acid) – EM. A 5–6-fold molar excess of copolymer/AgNP complexes SM/Ag⁰ or VM/Ag⁰ and approximately 10-fold excess of EM/Ag⁰ were used relative to C₆₀ (moles of copolymers corresponded to AgNPs containing dimer units of copolymers). The volume of the aqueous phase when preparing composites was correlated with the organic phase as 1 to 1–1.3. The physical and optical properties of the preparations were characterized by UV-vis and FTIR spectroscopy, DLS, TGA, TEM and XPS. It has been shown that fullerene is included in the composites in solvated form. The AgNP content in the composites was 22–34, and that of C₆₀ is 20–28 wt%. The dry composites were found to be dispersible in water, but were practically insoluble and did not dissociate in nonpolar solvents and NMP. It has been shown that C₆₀ significantly inhibits the oxidative degradation of AgNPs in the composites and increases the antifungal activity of the preparations against Candida albicans.