Zn2+ ions cross-linking sodium alginate encapsulated bacterial cellulose/ZnO composite film for antibacterial application

Abstract

To realize the biocompatibility, mechanical strength, and sustained antibacterial properties of medical materials, it is feasible to introduce antibacterial material components into biomass matrix to prepare medical materials. Herein, zinc oxide (ZnO) was in-situ synthesized in bacterial cellulose (BC) dispersion and filtered into a film, and the BC/ZnO composite film was further immersed in sodium alginate (Alg) solution to construct the second layer structure. The microstructure, mechanical strength, and antibacterial properties of the composite films were investigated systematically. The tensile strength of the BC/ZnO/CAlg sample was achieved at 16.5 ± 2.4 MPa, much higher than that of the Zn²⁺ crosslinked CAlg film of 11.5 ± 1.2 MPa. The Zn²⁺ cross-linked Alg in the outer layer and the BC/ZnO composite film in the inner layer combined to create a synergistic effect. This secondary structure design ensures good hydrophilicity and hygroscopicity of the material which enables the sustained-release migration of Zn²⁺ from the inner layer to the outer layer. Finally, the BC/ZnO/CAlg composite film possesses excellent antibacterial performance against Staphylococcus aureus and Escherichia coli. In addition, this work systematically expounds on the antibacterial and slow-release mechanism of secondary structure composite membranes. The results will provide a database and theoretical reference for applying BC/ZnO/CAlg composite membranes in the medical field.