A biocompatible polylactide-ε-caprolactone polymer coated with poly(hexamethylene biguanide) displays antibacterial properties against slime-producing S. epidermidis

Abstract

Introduction: produced by renewable resources, biodegradable polymers with their competitive mechanical properties, thermal stability and biocompatibility are important alternatives to other synthetic materials for use in medical devices, i.e. endotracheal suction catheters. However, infected catheters may lead to nosocomial infections, such as lower respiratory tract infections, with mechanical ventilation being a major risk for these. Antimicrobially coated endotracheal suction catheters may be one measure to reduce this risk. Methods: two procedures using ethanol and sodium hydroxide were tested to immobilize poly(hexamethylene biguanide) (PHMB) to polylactide-ε-caprolactone (PLA-ε-CL). The cytocompatibility of the coating was verified via the MTT assay and cytokine analysis in a cell monolayer and in a 3D mucosa model. The antimicrobial efficacy was tested using S. epidermidis; after this bacterial contamination and the adherence and viability of cells were tested. Chemical surface analysis has been performed with pristine and PHMB-coated specimens by means of infrared spectroscopy (ATR-FTIR). Results: with both applied coating procedures, PHMB could be immobilized onto the PLA-ε-CL surface. The biocompatibility of PLA-ε-CL was not impaired by the PHMB coating. IL-1α was slightly but significantly increased. Reduction of S. epidermidis was about 4 lg-levels after 6 h of incubation. Contamination of the surface prior to cell culture did not impair the adherence of the cells. Conclusion: we demonstrated that PLA-ε-CL coated with PHMB has good biocompatible properties with antimicrobial activity thus revealing the polymer to be a suitable material for the development of medical devices that are able to prevent bacterial contaminations and infections.