Nanocomposite film with antimicrobial activity based on gold nanoparticles, chitosan and aminopropylsilane

Abstract In the present work the role that 3-aminopropyltrimethoxysilane (APTMS) plays in the chitosan‑gold nanoparticles system was studied. For this purpose, gold nanoparticles (AuNP) (ca. 4.0 nm), were synthesized using chitosan as stabilizer and after, the APTMS, which presents both alkoxy and amine groups, was added to the system. No changes in both size and shape of the AuNP were observed. The addition of APTMS to chitosan produced a significant decrease in dynamic viscosity and this feature can contribute to the achievement of greater miscibility in the system. The AuNP dispersion containing APTMS was used to build a film on the surface of glass slide by using the drop-casting method. The gold amount on the resulting film was estimated as 17.5 μmol of gold atoms per cm2, in the nanoparticle form. The film was analyzed by UV–Vis, TEM, SEM, perfilometry and AFM. The film presented thickness of 36 μm, while the estimated roughness was lower than 1% of this value. The antimicrobial activity of the film based on chitosan, APTMS and gold nanoparticles was evaluated against Salmonella bacterium. The synergistic effect of the three components provided greater antimicrobial activity.