Zinc–gallic acid–polylysine nanocomplexes with enhanced bactericidal activity for the treatment of bacterial keratitis

Abstract Bacterial keratitis is a common infectious eye disease. Conventional antibiotic eye drops are becoming less effective due to antibiotic resistance. Herein, we design an innovative transition metal ion-based nano-delivery system for the treatment of bacterial keratitis. Zinc (Zn 2+ )–gallic acid–poly- l -lysine nanocomplex (ZGNC) is designed by coordination interaction. ZGNC is stable in a physiological environment and can be dissociated in an acidic infected microenvironment. The positively charged ZGNC can be effectively adhered onto bacterial cells and subsequently realizes in situ release of Zn 2+ , leading to much better bactericidal effect than free Zn 2+ . Importantly, ZGNC maintains excellent bactericidal activity in a protein-rich environment, while free Zn 2+ is completely invalid to eradicate bacteria in a protein-rich environment. The in vivo bactericidal ability of ZGNC is further confirmed in a murine bacterial keratitis model. This research provides a promising method to treat bacterial keratitis by a transition metal ion-based nano-delivery system.