Novel, UV-curable coatings containing a tethered biocide: Synthesis, characterization, and antimicrobial activity

Cationic, UV -curable coatings containing the tethered biocide, triclosan, were produced and their antimicrobial activity toward Staphylococcus epidermidis and Escherichia coli determined. Two polysiloxanes functionalized with both cycloaliphatic epoxy and triclosan were synthesized using hydrosilylation. The functionalized polysiloxanes, with varied concentration of pendant triclosan, were used to produce UV-curable coatings with reasonably good coating properties. Fourier transform (FT)-Raman spectroscopy showed that the tethered triclosan moieties self-concentrate on the coating surface. Using biological assays, it was determined that the coatings possessed nearly 100% antimicrobial activity toward the Gram-positive bacterium, S. epidermidis, without leaching toxic components. For the Gram-negative bacterium, E. coli, 60-80% reduction in biofilm retention was observed for all the coatings. Interestingly, the coatings were lesser effective in reducing E. coli cell viability suggesting that the tethered triclosan were able to substantially reduce the production of the biofilm extracellular matrix with minimal adverse affect on the bacterial cells attached to the coating surfaces. The high specificity of the coatings toward S. epidermidis indicates that a novel mode of contact-active antimicrobial activity was achieved through the disruption of processes unique to the Gram-positive cell wall. These novel UV-curable coatings have potential applications in inhibiting implantable biomedical device associated infections.