Preparation of biocompatible nano-ZnO/chitosan microspheres with multi-functions of antibacterial, UV-shielding and dye photodegradation.

Nano-ZnO (nZnO) has been widely used as antibacterial, UV-shielding and photocatalysis materials, but limited by its contentious biosafety. In this paper, chitosan (CS) was introduced to enhance the biocompatibility. To solve the problem that nZnO reacts with the CS acid solution, alternate-feed spray drying was adopted to fabricate nZnO/CS composite microspheres. It was showed that nZnO remained the hexagonal phase, dispersed and embedded into CS microspheres. Based on the results of cytotoxicity and hemolysis test, biosafety was improved obviously. Further, the antibacterial activity of nZnO/CS was notably better than either of CS and nZnO individually. UV-shielding property and photocatalytic degradation test were estimated. In a word, alternate-feed spray drying presents a novel and cost-efficient method to fabricate multifunctional nZnO/CS microspheres with enhanced biosafety.