Multifunctional nanogel coatings
provide a promising antimicrobial strategy against biomedical implant-associated
infections. Nanogels can create a hydrated surface layer to promote
antifouling properties effectively. Further modification of nanogels
with quaternary ammonium compounds (QACs) potentiates antimicrobial
activity owing to their positive charges along with the presence of
a membrane-intercalating alkyl chain. This study effectively demonstrates
that poly(N-isopropylacrylamide-co-N-[3(dimethylamino)propyl]methacrylamide)
(P(NIPAM-co-DMAPMA)-based nanogel coatings possess
antifouling behavior against S. aureus ATCC 12600, a Gram-positive bacterium. Through the tertiary amine
in the DMAPMA comonomer, nanogels are quaternized with a 1-bromo-dodecane
chain via an N-alkylation reaction. The alkylation introduces the
antibacterial activity due to the bacterial membrane binding and the
intercalating ability of the aliphatic QAC. Subsequently, the quaternized
nanogels enable the formation of intraparticle hydrophobic domains
because of intraparticle hydrophobic interactions of the aliphatic
chains allowing for Triclosan incorporation. The coating with Triclosan-loaded
nanogels shows a killing efficacy of up to 99.99% of adhering bacteria
on the surface compared to nonquaternized nanogel coatings while still
possessing an antifouling activity. This powerful multifunctional
coating for combating biomaterial-associated infection is envisioned
to greatly impact the design approaches for future clinically applied
coatings.