Novel chitosan-encapsulated ZnO NPs@Subtilisin: enzyme immobilized as next-generation nanoplatform for antimicrobial and anticancer control

Abstract

Antibiotic resistance has become a major global health concern, significantly reducing the effectiveness of existing antimicrobial treatments. This issue, largely driven by the excessive and inappropriate use of antibiotics, has led to increased morbidity, longer hospital stays, and higher mortality rates. At the same time, lung cancer continues to be one of the deadliest cancers worldwide, with high incidence and poor survival outcomes. These challenges highlight the urgent need for innovative therapeutic approaches that can address both microbial infections and cancer. In this study, we developed a multifunctional nanosystem with both antibacterial and anticancer potential. Zinc oxide nanoparticles (ZnO NPs) were synthesized using eggshell membrane as a biological template. A targeted delivery system was then constructed by immobilizing the enzyme subtilisin onto the nanoparticle surface and encapsulating the complex within a chitosan matrix to improve stability and activity. The biological performance of the system was evaluated against A549 lung cancer cells and various bacterial strains, including Gram-positive and Gram-negative species. This study demonstrates that the ZnO/subtilisin nanocomposite had stronger antibacterial activity against E. coli and Pseudomonas aeruginosa than against Staphylococcus aureus and S. mutans . The results demonstrated strong inhibitory effects, attributed to mechanisms such as ion release, membrane interaction, and oxidative stress. This nanosystem shows promise as a dual-function therapeutic platform.