Surface Modification of Silicone for Biomedical Applications Requiring Long-Term Antibacterial, Antifouling, and Hemocompatible Properties

Silicone has been used for peritoneal dialysis (PD) catheters for several decades. However, bacteria, platelets, proteins, and other biomolecules tend to adhere to its hydrophobic surface, which may lead to PD outflow failure, serious infection, or even death. In this work, a cross-linked poly­(poly­(ethylene glycol) dimethacrylate) (P­(PEGDMA)) polymer layer was covalently grafted on medical-grade silicone surface to improve its antibacterial and antifouling properties. The P­(PEGDMA)-grafted silicone (Silicone-g-P­(PEGDMA)) substrate reduced the adhesion of Staphylococcus aureus, Escherichia coli, and Staphylococcus epidermidis, as well as 3T3 fibroblast cells by ≥90%. The antibacterial and antifouling properties were preserved after the modified substrate was aged for 30 days in phosphate buffer saline. Further immobilization of a polysulfobetaine polymer, poly­((2-(methacryloyloxy)­ethyl)­dimethyl-(3-sulfopropyl)­ammonium hydroxide) (P­(DMAPS)), on the Silicone-g-P­(PEGDMA) substrate via thiol–ene click reaction leads to enhanced antifouling efficacy and improved hemocompatibility with the preservation of the antibacterial property. Compared to pristine silicone, the so-obtained Silicone-g-P­(PEGDMA)-P­(DMAPS) substrate reduced the absorption of bovine serum albumin and bovine plasma fibrinogen by ≥80%. It also reduced the number of adherent platelets by ≥90% and significantly prolonged plasma recalcification time. The results indicate that surface grafting with P­(PEGDMA) and P­(DMAPS) can be potentially useful for the modification of silicone-based PD catheters for long-term applications.