Preparation Of Polyoxometalate Nanomedicines And Its Application In Photothermal Antibacterial Therapy

In recent years,the number of diseases caused by bacteria has been increasing.However,due to the abuse and improper treatment of antibiotics in the traditional treatment methods,the drug resistance of bacteria has been increasing,and the emergence of new biofilms makes the cure rate of diseases lower and lower.Therefore,in order to solve these problems,more and more new treatments have attracted widespread attention of scientists.Recently,due to the characteristics of space structure diversity,skeleton structure stability and strong ability to accept electrons,polyoxometalate nanomedicines have been applied in the field of biomedicine,especially in antitumor and antibacterial research.In this thesis,two kinds of nanocluster of gadolinium polytungstate(Gd W₁₀O₃₆)and gadolinium phosphotungstate(Gd P₅W₃₀O₁₁₀)were synthesized,and then the gadolinium polytungstate nanoclusters were mixed with glutathione?GSH?for redox reaction to obtain the corresponding reduced polyoxometalates.At the same time,the gadolinium phosphotungstate nanocluster and the transition metal sulfide?tungsten disulfide WS₂?were combined to obtain the Gd P₅W₃₀O₁₁₀@WS₂ composite material.Subsequently,the synergistic antibacterial effect of reduced Gd W₁₀O₃₆ NCs and Gd P₅W₃₀O₁₁₀@WS₂ composites as both peroxidase and photothermal absorbent was studied.The specific research work of this paper can be summed up in the following two aspects:1.The gadolinium polytungstate nanoclusters were prepared by a simple recrystallization method,and then reduced Gd W₁₀O₃₆ NCs was synthesized by the redox reaction of gadolinium polytungstate nanoclusters and glutathione.Characterization of Gd W₁₀O₃₆ and reduced Gd W₁₀O₃₆ NCs by FT-IR,UV-vis,XPS,TEM and DLS proved the successful synthesis of Gd W₁₀O₃₆ and reduced Gd W₁₀O₃₆NCs,and the gadolinium polytungstate nanoclusters exhibit high hydrophilicity and small size under neutral conditions,but in acidic environment,it can self-assemble by hydrogen bonding to form larger aggregates.Gd W₁₀O₃₆ has strong characteristic absorption in the near-infrared region after being reduced by GSH,which significantly improves the photothermal conversion performance of Gd W₁₀O₃₆ NCs.At the same time,the reduced Gd W₁₀O₃₆ can be used as a peroxide-like enzyme to catalyze the decomposition of endogenous hydrogen peroxide to generate a large number of hydroxyl radicals,so as to effectively inhibit bacterial proliferation,eliminate bacterial biofilm,achieve the synergistic antibacterial effect of peroxide-like enzyme and photothermal treatment,and make up for the deficiency of single mode of antibacterial.In addition,the ability of reduced Gd W₁₀O₃₆ NCs with synergistic antibacterial activity to promote wound healing was studied in vivo on animals,and it was found that reduced Gd W₁₀O₃₆ NCs not only effectively inhibit bacterial proliferation,but also promote the differentiation of fiber cells and skin regeneration,making wounds healing faster.2.Gadolinium phosphotungstate was prepared by two-step hydrothermal reaction,and tungsten sulfide was prepared by pickling intercalation layer.Then Gd P₅W₃₀O₁₁₀ and WS₂ were connected together by amide bond to obtain Gd P₅W₃₀O₁₁₀@WS₂composite material.A series of characterization of Gd P₅W₃₀O₁₁₀@WS₂ composites,including FT-IR,UV-vis,XRD,Raman,TEM,DLS and zeta potential,have proved the successful synthesis of the composites.The photothermal performance and peroxidase-like catalytic activity experiments show that the Gd P₅W₃₀O₁₁₀@WS₂ composite material is a good peroxidase and photothermal absorbent.In addition,the biotoxicity and synergistic antibacterial experiments show that the Gd P₅W₃₀O₁₁₀@WS₂ composite material not only has low biotoxicity,but also can be used as a peroxidase and photothermal agent for synergistic antibacterial,and the effect is better than that of a single antibacterial model.The composite material shows much better antibacterial effect than Gd P₅W₃₀O₁₁₀ and WS₂ under the same conditions.