Responsive antibacterial surface based on looped poly(methacrylic acid)

The adhesion of bacteria to surfaces poses a significant challenge to public health and many industries, making the development of antibacterial surfaces an urgent issue. In this work, α,ω-bisthiol poly(methacrylic acid) (HS-PMAA-SH) was synthesized and grafted in loop conformation onto a substrate primed with polydopamine, in conjunction with Ag NPs prepared in-situ to create a pH responsive composite surface with synergistic fouling-resistant and bacterial killing and releasing capabilities. A monofunctional analogue of half the chain length, PMAA-SH, was also synthesized and used to construct the composite surface with the PMAA in linear conformation for comparison. Quartz crystal microbalance with dissipation experiments revealed that PMAA loops allowed much less protein to adsorb than their linear analogues. Confocal laser scanning microscopy results showed that both composite surfaces were effective in killing the bacteria attached due to the presence of Ag NPs, and exhibited good initial resistance to bacterial adhesion and ability to release the killed bacteria under mild conditions due to the PMAA component; the composite surface conjugated with PMAA-loop was superior to the one with PMAA-linear, presenting lower initial bacterial adhesion and higher release rates, maintaining a low bacterial coverage even after five resist/kill/release cycles. The research opens a new avenue for antibacterial surfaces that integrate fouling-resistance, bacterial killing and release functions.