Construction Of Polymer-decorated GO-stabilized Silver Nanohybrids Based On Mussel-inspired Chemistry And Their Antibacterial Properties

In recent years,the problem of bacterial resistance to antibiotics brings huge challenges to humans.Metal nanoparticles(NPs),such as Ag NPs,Cu NPs,and Au NPs,have been widely used in the antibacterial field because of their relatively large specific surface area and special antibacterial mechanism.However,NPs are easy to aggregate into larger particles.This shortcoming limits the effective contact area between NPs and bacteria,thereby reducing their antibacterial activity.This disadvantage of NPs can be overcome by loading them on the corresponding substrate surface.Among them,the graphene in inorganic materials is an ideal carrier of metal nanoparticles because of its excellent conductivity,antibacterial property,relatively large specific surface area and rich oxygen-containing functional groups.More importantly,the synergistic effect between graphene and NPs can significantly improve the antibacterial activity of nanomaterials.However,the complex process in the synthesis of composite materials is very easy to lead to the aggregation of graphene and its destruction of surface structure.Therefore,it is a very promising method to introduce polymer which can stabilize NPs and reduce the destruction of graphene materials during its synthesis.In this thesis,we designed and constructed a new type of hydrophilic polymer-modified graphene supported silver nanohybrid antibacterial material based on the Mussel-inspired chemistry strategy.The detailed work includes the following two parts:In the first part,inspired by Mussel chemistry,a kind of quaternized polymer-modified reduced graphene oxide supported silver nanohybrid(rGO-QCP-Ag)was designed and synthesized and used as an efficient antibacterial agent and nanocatalyst.The rGO-QCP-Ag nanohybrid had high positive charge density and decent hydrophilic properties,and the Ag nanoparticles deposited on rGO exhibited ultra-small size and dispersion stability.The as-prepared nanohybrid showed high-efficacy and long-term antibacterial properties against E.coli(G-)and S.aureus(G+),especially,it could rapidly kill E.coli within 2 h at a concentration of 16 ?g/m L.The antibacterial mechanism of nanohybrid mainly involved cell membrane damage and reactive oxygen species(ROS)generation.Besides,the nanohybrid displayed highly efficient catalytic reduction activity for p-nitrophenol and methylene blue.The excellent antibacterial and catalytic properties of the nanohybrid are mainly attributed to its water dispersion stability and the uniformly dispersed small-sized Ag nanoparticles on the polymer-decorated rGO sheets,at the same time,combining with the synergistic effect of two-dimensional rGO sheets.The above characteristics enable the nanohybrid to get in contact with bacteria and reactants effectively,thus significantly enhancing the antibacterial and catalytic properties of the materials.In the second part,a novel catechol-terminated copolymer(CCP)containing hydrophilic poly(ethylene glycol)methyl ether methacrylate(PEGMA)and coordination functional poly(2,3-epithiopropyl methacrylate)(PETMA)segments was prepared via reversible addition-fragmentation chain transfer radical polymerization.The polymer can be easily functionalized to the surface of rGO through mussel-inspired chemistry under mild room temperature conditions.The obtained CCP-rGO two-dimensional nanosheets as a platform were utilized to construct CCP-rGO supported well-dispersed Ag nanoparticles composite(CCP-rGO-Ag)through situ reduction means.The as-prepared CCP-rGO-Ag nanocomposite has powerful and long-lasting antibacterial activity against G-(E.coli)and G+(S.epidermidis and S.aureus),and potently reduces the cytotoxicity of nanomaterials.Compared with rGO-Ag without polymer modification,CCP-rGO-Ag in solution has super antibacterial performance due to the introduction of a hydrophilic coordination polymer having the ability to stabilize and dispersing Ag NPs in nanomaterials.