Bacterial cellulose composite modified by tea polyphenols and ultrasmall copper nanoparticles with antimicrobial and antioxidant activities

The lack of antimicrobial and antioxidative properties limits the practical application of bacterial cellulose (BC) in chronic ulcers, where prolonged inflammation and infection are common. To address this issue, we decorate BC with tea polyphenols (TP) and copper nanoparticles using an in-situ reduction method. Transmission electron microscopy and X-ray photoelectron spectroscopy analyses reveal that ultrasmall copper nanoparticles reduced by TP are evenly deposited on the nanofibers. The deposition of copper nanoparticles, approximately 3 nm in size with a content of 2.05 wt%, does not affect the morphology or crystallinity of BC. The composite exhibits strong antimicrobial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, as demonstrated by growth curves and inhibition zone tests. Radical scavenging experiments indicate significant antioxidative capability, with 90.3% inhibition of DPPH radicals and nearly 100% inhibition of ABTS radicals after 24 h. Furthermore, the composite significantly enhances L929 cell attachment, showing a 1.5-fold increase in cell attachment after 3 h. The migration rates of L929 cells are 95.6% for the composite and 53.8% for BC after 96 h, respectively. Due to these performances, this composite presents a promising new paradigm for chronic wound healing.