Design of AgNPs doped chitosan/sodium lignin sulfonate/polypyrrole films with antibacterial and endotoxin adsorption functions

There is an urgent need to develop materials to prevent bacterial infection and the deleterious effects of endotoxins. In this study, we introduce a one-step electrodeposition method to prepare films composed of chitosan/Ag/polypyrrole and layer-by-layer self-assembly to introduce lignin sulphonate (LS) to obtain chitosan/Ag/polypyrrole/LS films. Antibacterial effects against both E. coli and S. aureus are shown by bacterial growth profiles and observation of bacteriostatic zones. Meanwhile, the addition of self-assembled LS improved the antibacterial effect of the film. For E. coli, the inhibition zone diameter was 0.93 cm, while for S. aureus, the inhibition zone diameter was 0.72 cm. Rapid and efficient endotoxin adsorption effects were shown whereby the electrostatic interactions between chitosan and endotoxin molecules played a major role. After adsorption for 1 h, in initial concentration of 1 EU/mL endotoxin solution, the adsorption efficiency could reach up to 85 %, while in initial concentration of 5 EU/mL endotoxin solution, the adsorption efficiency could reach up to 87.6 %. The results suggest chitosan/Ag/polypyrrole/LS films for their capability as a new type of antibacterial film with intrinsic endotoxin adsorption activity.