Synergistic defence: Dual-functional silk sericin/tannic acid-silver composites against bacteria and biofilms

Bacteria are everywhere in our daily lives. Some are beneficial to the human body, while others can cause various problems ranging from minor infections to serious diseases. In this study, silk sericin/tannic acid-silver (SS/TA-Ag) nanocomposites were synthesized via a water bath method. SEM results indicate that the SS/TA-Ag composite exhibits an irregular morphology, while TEM analysis reveals the presence of spherical Ag nanoparticles. The results showed that 3 mg/mL SS/TA-Ag nanocomposites have excellent antibacterial properties, with antibacterial rates of 94.2 % and 79.8 % against Staphylococcus aureus and Escherichia coli, respectively. The antibacterial mechanism is primarily attributed to the ability of silver nanoparticles to interact with bacterial cells, damaging their membranes and altering cellular structure. This inflicts physical damage on the bacteria, ultimately leading to cell death. While it exhibited excellent anti-biofilm properties with an inhibition rate as high as 85.1 %. The obtained SS/TA-Ag nanocomposites not only have dual antibacterial and anti-biofilm functions, but also have a simple preparation process and mild reaction conditions, which are in line with the concepts of green chemistry and environmental friendliness.