Abstract
The nonspecific adsorption of proteins and bacteria on the surface of polydimethylsiloxane (PDMS) had been a serious concern in a wide range of applications, such as medical devices. In order to improve the anti-adhesive and antibacterial capability, bare silver nanoparticles (AgNPs, ~15 nm) were generated in-situ on their surface without extra reducing and stabilizing agents. The main reason for this was that the SiO2 microspheres that are covalent bonded to the bulked PDMS could not only generate AgNPs spontaneously but also insure that no AgNPs were released to the environment. Meanwhile, the thiol-group-functionalized SiO2 microspheres self-assembled on the surface of PDMS by thiol-vinyl click reaction without any impact on their biomedical applications. After the modification of SiO2 microspheres with AgNPs, the surface of PDMS showed a smaller water contact angle than before, and the adhesion and growth of E. coli and Bacillus subtilis were effectively inhibited. When the monolayer of SiO2 microspheres with AgNPs was assembled completely on the surface of PDMS, they present improved bacterial resistance performance (living bacteria, 0%). This approach offers an antibacterial and anti-adhesive surface bearing small and well-defined quantities of in-situ generated AgNPs, and it is a novel, green, simple, and low-cost technique to generate AgNPs on soft biomedical substrates.
Highlights
Polydimethylsiloxane (PDMS) is optically clear, inert, non-toxic, and one of the most widely used silicon-based organic polymers, which have been applied in contact lenses [1], elastomers [2], cosmetics [3], food [4], medicine [5], and medical devices [6]
Many strategies have been employed to improve the antifouling performance of PDMS, including surface modification with biomimetic components coating [9,10]. These modified hybrids often suffered from limitations, such as weak interfacial bonding and low robustness [11,12]. These materials are incapable of acting against bacteria once they adhere onto the surface, so an ideal antifouling material should present both anti-adhesive and antibacterial capability
Ltd. (Shanghai, China) Tryptic soy broth medium (TSB) and tryptic soy agar medium (TSA) were purchased from Hangzhou Microbial Reagent Co., Ltd. (Hangzhou, China) Fluorescent dyes Hoechst33342 and PI were purchased from Beijing Solarbio science & technology Co., Ltd.(Beijing, China) All the reagents were used without further purification
Summary
Polydimethylsiloxane (PDMS) is optically clear, inert, non-toxic, and one of the most widely used silicon-based organic polymers, which have been applied in contact lenses [1], elastomers [2], cosmetics [3], food [4], medicine [5], and medical devices [6]. The ideal AgNPs-based antibacterial biomaterials should cause minimal damage to healthy human cells, have AgNPs tightly bound to the material surface, and have the capability to control the AgNPs density on the surface of biomaterials They should release only silver and not organic ligands if bacteria are present, in order to maximize the antibacterial effect from AgNPs. To overcome the challenge of loading the AgNPs antibacterial and anti-adhesive surface to PDMS, we designed the silica microspheres (SMs) with in-situ growth of AgNPs on their surface, and the size of the as-prepared AgNPs (~15 nm) could be controlled by tuning the concentration of Ag+ ions in our recent report [26]. Upon UV or visible light irradiation, the thiol groups on the surface of SMs, as one clickable function group, would anchor the SMs to the surface of PDMS by expediently combining with the other clickable function groups (e.g., terminal vinyl groups) modified on the surface of PDMS membranes
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