Silica-chitosan nanocomposite mediated pH-sensitive drug delivery

Stimuli-based drug release is extremely important for therapeutics and organ-specific drug delivery. Chitosan (CS), a deacetylated form of chitin, natural biopolymer, having wide range of properties including antimicrobial and antifungal. High surface area silica nanoparticles (Si NPs) are good drug-vehicular candidates. Curcumin (Cu), a well-known anti-microbial, anti-cancer, anti-fungal, anti-inflammatory drug has been loaded (in-situ) onto the CS-Si NPs nanocomposite, synthesized using sol gel method to yield CS-Si-Cur NPs. The bare (Si-Cur NPs)and drug-loaded (CS-Si-Cur NPs) show particle size of ∼30 nm and ∼130 nm respectively. UV-visible spectroscopy shows the Cur peak at 430 nm; especially of the active enolic group, and the drug loading efficiency ∼60%. Conjugation studies reveal that a weak hydrogen bonding hold the Cur drug molecules in conjugated system. The pH dependent release of Cur drug at pH 4, pH 7.4 and pH 9.2 reveal that 100%, 60% and 35% drug release in 48 h, respectively, at 37 °C (∼body temperature). CS-Si-Cur NPs showing good antimicrobial activity against B. subtilis, Salmonella. thyphimurium, Serritia mercescens, Proteus vulgarism and S. aureus. A pH-sensitive, antimicrobial formulation is hence suggested, whose release profile can be tuned using the pH of the release media.