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.