Study Of MoS₂/PVA Antibacterial Composite Hydrogels With Near-Infrared Light-Response

Bacterial infections have always threatened human health.Antimicrobial biomaterials have been developed as alternatives to antibiotics due to the increase in bacterial resistance,excessive or inappropriate use of antibiotics.Among them,antibacterial hydrogels have attracted much attention due to their simple preparation process and diverse structures,which can endow them with various functions such as high toughness and stretchability.Based on this,in this paper,silver nanoparticles and quaternary ammonium salt chitosan were coated on the surface of molybdenum disulfide（MoS₂）,respectively,and introduced into polyvinyl alcohol（PVA）hydrogels.Based on the efficient near-infrared photothermal effect of MoS₂,the antibacterial effect of MoS₂combined with other antibacterial materials the antibacterial was studied.Meanwhile,the structure and properties of the responsive hydrogel were explored.To further broaden the application of hydrogels in the biomedical field,the quaternary ammonium salt chitosan-molybdenum disulfide/polyvinyl alcohol（QCS-MoS₂/PVA）hydrogels were soaked in polyphenol-structured tannic acid（TA）solution,and the mechanical properties and adhesion of the composite hydrogels were investigated.The main research contents are as follows:（1）MoS₂was synthesized through hydrothermal method,and then molybdenum disulfide@polydopamine and molybdenum disulfide@polydopamine@silver（MoS₂@PDA and MoS₂@PDA@Ag）were synthesized by using tris（hydroxymethyl）amino methane hydrochloride（Tris-HCl）and silver ammonia solution in turn.the structures of MoS₂,MoS₂@PDA,and MoS₂@PDA@Ag were characterized by Ultraviolet visible spectroscopy（UV-vis）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,and transmission electron microscopy（TEM）.The synthesized composite nanoparticles were then added to the PVA solution to form MoS₂/PVA,MoS₂@PDA/PVA,and MoS₂@PDA@Ag/PVA composite hydrogels through freeze-thaw cycles.The hydrogen bonding interaction between MoS₂-based nanoparticles and PVA molecular chains significantly improved the mechanical properties of the hydrogels.The hydrogels exhibited good photothermal effect and antibacterial activity,and Ag doping significantly enhanced its photocatalytic performance.Due to the synergistic effect of reactive oxygen species and high temperature,the hydrogels exhibited good antibacterial activity after being irradiated with 808 nm near-infrared light for 15 min.At the same time,in vitro 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide（MTT）assay further demonstrated that the hydrogels were non-toxic to mouse fibroblasts cells（L929）.Furthermore,compared with pure PVA,MoS₂@PDA@Ag/PVA hydrogels can promote wound healing,showing potential in alleviating bacterial infection of wounds.（2）Based on the hydrothermal synthesis of MoS₂,a quaternary ammonium salt chitosan-coated molybdenum disulfide（QCS-MoS₂）nanomaterial was successfully prepared.A physically cross-linked PVA composite hydrogel was then prepared by a sol-gel method.After the introduction of QCS-MoS₂,QCS-MoS₂can act as a crosslinking agents to form a hydrogen-bonding network with the PVA hydrogels matrix,thereby significantly improving its mechanical properties.The photothermal properties of QCS-MoS₂/PVA hydrogels were investigated,and it was found that the photothermal properties of the hydrogels were proportional to the content of QCS-MoS₂.In addition,the inhibition zone method showed that the composite hydrogels had excellent antibacterial properties.And after 15 minutes of near-infrared light irradiation,the antibacterial rates against Staphylococcus aureus（S.aureus）and Escherichia coli（E.coli）can reach 94.60 and 98.82%.Meanwhile,MTT results showed that the introduction of QCS-MoS₂had no obvious effect on cell viability,showing good biocompatibility.（3）The QCS-MoS₂/PVA hydrogels were soaked in different concentrations of TA solution to obtain the QCS-MoS₂/PVA/TA composite hydrogels.The polyphenolic structure of TA was utilized to form various interactions with PVA molecular chain,thereby significantly improving the performance of the hydrogels.The study showed that after soaking in TA,the pores of QCS-MoS₂/PVA/TA hydrogels became more compact with the increase of TA concentration.In addition,the mechanical properties and adhesion properties were positively correlated with the TA concentration.Among them,the compressive strength and tensile strength can reach 2.42 and 1.35 MPa,respectively,which were 14.0 and 12.3 times that of the QCS-MoS₂/PVA hydrogels.And the maximum elongation at break was 451%.Adhesion experiments showed that the hydrogels were capable of adhering substances up to 50.0 g weight.Meanwhile,the introduction of TA endowed the composite hydrogel with excellent antibacterial properties.