Bacterial cellulose/silver composite film in-situ coated copper alginate for thermally responsive antimicrobial dressing

Intelligent, controlled, slow-release antimicrobial materials have shown excellent application prospects in the medical field. Herein, silver particles (Ag) were synthesized using the hydrothermal method and a bacterial cellulose (BC) membrane as a template. The BC/Ag composite membrane was clad with copper alginate (CAlg) via the in-situ dip-coating method. Based on the Cu 2+ ions in copper alginate, a layer of copper sulfide (CuS) was formed through a liquid-phase sulphuration reaction. This CuS layer leads the film to possess a photothermal and electrothermal response. Furthermore, we systematically investigated the microstructure, mechanical strength, and antibacterial properties of the composite film. The tensile strength of the BC/Ag/CAlg/CuS sample can reach 14.7 MPa, which should be attributed to the combination of the Cu 2+ cross-linked CAlg and the inner BC/Ag composite film. Meanwhile, this assembled film exhibited hydrophilic and hygroscopic properties, as the antibacterial Ag particles can be continuously released and migrated from the inner layer to the outer layer. Finally, the BC/Ag/CAlg/CuS film inhibited Staphylococcus aureus and Escherichia coli by 99.9% and 99.6%, respectively, which should be attributed to the synergistic effect of silver ions and CuS’s electrical and photothermal stimulation responses. These characteristics of the thermally responsive BC/Ag composite films indicate that they may successfully serve as wound dressings and other medical biomaterials.