A Novel Antibacterial Surface Coating of Polydimethylsiloxane Using Quaternary Ammonium Compound functionalized Poly(oligo(ethylene glycol) methyl ether methacrylate) Microgels

Abstract

Biofilms are a growing concern for medical implants and food processing because they can cause infections and resist antibiotics. One surface on which biofilms can form is polydimethylsiloxane (PDMS), a type of silicone rubber, which is often used for medical and food processing applications. The aim of this project is to prevent biofilm growth on PDMS by creating an antimicrobial surface coating based on microgels prepared using the anti-fouling polymer poly(oligoethylene glycol methacrylate) (POEGMA). These polymers were further functionalized with quaternary ammonium compounds (QACs) to incorporate antibacterial properties to reduce biofilm formation. The QAC-functionalized microgels were assembled in water and phosphate buffered saline (PBS) and were found to be stable over 20 days, with an average diameter of 240 nm. They also demonstrated excellent antimicrobial properties against both Staphylococcus aureus and Pseudomonas aeruginosa (Gram positive and negative respectively). The microgels showed a 9.56 log reduction (99.99999997% kill) against S. aureus and an 8.5 log reduction (99.999999% kill) against P. aeruginosa. To attach the microgels to PDMS, the PDMS was plasma treated to enable electrostatic binding between the originally hydrophobic PDMS and the cationic QAC-functionalized microgels. The effective immobilization of the microgels was confirmed using bromophenol blue (which turns blue in the presence of QACs) and atomic force microscopy (AFM). Finally, the microgel-coated PDMS demonstrated a 95% reduction of S. aureus which indicates this coating can sanitize PDMS. Future studies should be completed for microgel-PDMS bond strength and antimicrobial properties of PDMS-bound microgels. Ultimately, the QAC-functionalized POEGMA microgels were effective as an antibacterial coating on PDMS and could have applications such as a surface cleaner or a sterilizing agent to reduce the transmission of bacteria and prevent infections.