Antimicrobial PDMS Surfaces Prepared through Fast and Oxygen-Tolerant SI-SARA-ATRP, Using Na₂SO₃ as a Reducing Agent

Abstract

Poly­(dimethylsiloxane) (PDMS) is an attractive, versatile, and convenient material for use in biomedical devices that are in direct contact with the user. A crucial component in such a device is its surface in terms of antimicrobial properties preventing infection. Moreover, due to its inherent hydrophobicity, PDMS is rather prone to microbial colonization. Thus, developing an antimicrobial PDMS surface in a simple, large-scale, and applicable manner is an essential step in fully exploiting PDMS in the biomedical device industry. Current chemical modification methods for PDMS surfaces are limited; therefore, we present herein a new method for introducing an atom transfer radical polymerization (ATRP) initiator onto the PDMS surface via the base-catalyzed grafting of [(chloromethyl)­phenylethyl]­trimethoxysilane to the PDMS. The initiator surface was grafted with poly­[2-(dimethylamino)­ethyl methacrylate] (PDMAEMA) brushes via a surface-initiated supplemental activator and reducing agent ATRP (SI-SARA-ATRP). The use of sodium sulfite as a novel reducing agent in SI-SARA-ATRP allowed for polymerization during complete exposure to air. Moreover, a fast and linear growth was observed for the polymer over time, leading to a 400 nm thick polymer layer in a 120 min reaction time. Furthermore, the grafted PDMAEMA was quaternized, using various alkylhalides, in order to study the effect on surface antimicrobial properties. It was shown that antimicrobial activity not only depended highly on the charge density but also on the amphiphilicity of the surface. The fast reaction rate, high oxygen tolerance, increased antimicrobial activity, and the overall robustness and simplicity of the presented method collectively move PDMS closer to its full-scale exploitation in biomedical devices.

phoP maintains the environmental persistence and virulence of pathogenic bacteria in mechanically stressed desiccated droplets

“…Earlier, multiple studies reported a reduction in the viability of bacterial pathogens when exposed to antibacterial surfaces. 61 , 62 , 63 However, the present study demonstrated that investigating bacteria-laden drop impact on surfaces is highly relevant from the disease transmission perspective. This novel approach to droplet impact study opens a new dimension that brought out the effect of impact velocity-induced mechanical stress and evaporation-induced desiccation stress on the survival of bacteria in the nutrient-rich and nutrient-deficient medium.…”