Synthesis and quaternization of poly(vinyl benzyl chloride-co-3-(methacryloyloxy)propyl] trimethoxy silane) for inhibiting bacterial growth on dental implants

Dental implants are widely used to treat tooth loss, but because their surface is exposed to the oral environment, they are vulnerable to microbial colonization. To combat this, recent efforts have focused on engineering implant surfaces with antimicrobial properties. This work involved the synthesis of an antimicrobial coating by quaternizing the copolymer of vinylbenzyl chloride (VBC) and [3-(Methacryloyloxy)propyl]trimethoxy silane (MPS) of varying alkyl chain lengths. The MPS-VBC copolymer was synthesized using free radical polymerization, and quaternized to form ammonium salts of varying chain length (n): Trimethylamine (n = 1), Triethylamine (n = 2) and N,N -Dimethyl octylamine (n = 8). The quaternized ammonium salts (QAS) were characterized using ¹H NMR and FTIR spectroscopies. The antimicrobial effects of the QAS having different chain lengths were tested against both grampositive and gram-negative bacteria using different concentrations. The QAS with a chain length of n = 8 achieved a 99.9999 % reduction in E. coli and S. agalactiae, and a 99.99 % reduction in S. aureus. In contrast, QAS with shorter chain lengths (n = 1,2) showed no reduction in bacterial cells. The minimum inhibitory concentration (MIC) was found to be less than 10 mg/mL for all strains used in this study. The toxicity of our synthesized QAS was evaluated using Glutathione S-transferase (GST) activity. The QAS showed no cytotoxicity at MIC and MBC concentrations. This study opens pathways for using QAS in dental and oral pathways as they proved to be non-toxic when used orally.