Synthesis of pH-sensitive copolymer thin solid films embedded with silver nanoparticles for controlled release and their fungicide properties

Poly( methacrylic acid-co-butyl methacrylate) copolymer was synthesized which showed more than tenfold swelling above the pH of 4.5 within a narrow (0.5) pH range with the monomer composition of 85 mol% MAA and 15 mol% BMA. The water uptake properties of the prepared copolymers were adjustable by the monomer composition. Thin films were prepared consisting of a lower layer of silver nanoparticles (~ 0.033 mg/cm2) and an upper layer of pH-sensitive polymer (~ 2.0 mg/cm2). The AgNPs (d = ~ 20 nm) content of the layers was 1.64 wt%. Below pH 4.5,17 % of the active agent content was released after 1 h, however, at higher pH values (> 4.5) 100 % of the AgNPs left the thin layer. The antifungal effect was successful against Candida albicans, because the treatment with 10 ppm AgNPs dispersion killed 100 % of initial (~ 2.85 x 103 cfu/mL) yeast after 30 min. The minimal effective concentration of AgNPs is ~ 28500 cfu Candida albicans/mg AgNP for a contact time of 30 min.