The chemo enzymatic functionalization of chitosan zeolite particles provides antioxidant and antimicrobial properties

Silicate-based microporous materials like zeolites are nano enabled particles and used for various applications including pharmaceutical formulations. This study reports on the chemo-enzymatic functionalization of chitosan-zeolite particles (CTS-zeolites) with caffeic acid (CA) and glucose oxidase (GOX) to impart combined antioxidant and antimicrobial properties. CA was grafted on the chitosan moieties by using laccase generating stable particles (zeta potential -36.7 mV) of high antioxidant activity (44% DPPH inhibition). GOX was immobilized both on CTS-zeolites and on CA modified CTS-zeolites and creating a hydrogen peroxide generation system continuously and in-situ producing this oxidative and antimicrobial agent. The system prevented bacterial growth of E. coli and S. aureus over 24 h whereby a steady-state concentration of around 60 μM hydrogen peroxide in the culture medium was observed. CA and GOX functionalized CTS-zeolite particles additionally showed combinatorial antioxidant and antimicrobial properties providing a powerful bioactive system for medical applications. These particles proved their suitability for incorporation in bioactive formulations which could be used, inter alia, for topical wound treatments.