Layer-by-layer assembly of antibacterial composite coating for leather with cross-link enhanced durability against laundry and abrasion

Due to the breathable and soft nature, leather has been selected as flexible material to produce comfortable shoes. However, due to the intimate contact between leather surface and foot skin, bacteria growth and rapid colonization on leather surface can lead to biofilm formation which will bring potential risk of foot infection. Especially for those patients with diabetic foot, such foot infection can be life threatening. In this work, a composite coating was facilely fabricated onto leather surface via the layer-by-layer assembly of positively charged chitosan (CS) and negatively charged gallic acid modified silver nanoparticles (GA@AgNPs), with subsequent immobilization on leather by chemical cross-linking. Such cross-linked CS/GA@AgNPs coated leather exhibited efficiently antibacterial activities against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) through a “kill-release” strategy, which was mainly attributed to the synergistic effect of contact-killing of CS layer, Ag + ions release and bacterial repelling of anionic GA@AgNPs layer. Furthermore, the stability of the composite coating on leather surface was investigated, and the results revealed that the cross-linking could enhance the durably antibacterial activities of leather against laundering and mechanical abrasion. Therefore, based on the efficiently and durably antibacterial properties, such cross-linked CS/GA@AgNPs layers coated leather is a promising candidate for producing leather shoes for diabetic patients.