Covalently construction of poly(hexamethylene biguanide) as high-efficiency antibacterial coating for silicone rubber

[Display omitted] •Novel approach to combat biofilm formation and devices-associated infection.•Facile fabrication of high-efficiency antibacterial coating.•Robust relationship between surface chemistry and antibacterial capacity.•Significantly suppressed inflammation with good cytocompatibility. Biofilm formation on biomedical devices & implants and the resulting bacterial induced infections are remaining severe clinic issues. Here, a facile layer-by-layer strategy to covalently construct poly(hexamethylene biguanide) (PHMB) as the high-efficiency bactericidal coating on silicone rubber (SR) has been developed. Based on the NHS/NH2 chemistry (the reaction between active ester groups and amino groups), an active ester homo-polymers (pNHSMA) as the precursor layer was created on activated SR surface (SR-NH2), which followed by the immobilization of dense PHMB coating. XPS and water contact angle tests verified the successful construction of PHMB coating on the surface. Robust relationships between the contact time/initial seeding density of bacteria and the bactericidal capacity of the coating have been established based on systematical qualitative and quantitative antibacterial evaluations. Results showed that the PHMB coating is able to kill 100% of the attached S. aureus cells within 1 h with initial density below 1.18 × 105 CFU/cm2 without compromising of the cytocompatibility of the substrates. Interestingly, the coating significantly increased the mechanical property of the SR substrates due to the additional crosslinking introduced by the coating. Furthermore, the high-efficiency antibacterial property of PHMB coating (bactericidal ratio of 96.83%) and the significant suppressed implant-induced infection have been verified via the in vivo simulated infection model on rats. In the meantime, this surface modification strategy can be easily applied to SR based catheters, which is able to completely kill the surface attached bacteria when immersed in a bacterial suspension with a density of 3 × 106 CFU/mL for 30 min. These findings provide a new approach to combat the biofilm formation and devices-associated infections for general SR based biomedical devices/implants.