Design And Antitumor Application Of Photothermal Composite Hydrogel Based On Manganese Dioxide And Molybdenum Polyoxometalate

Due to the limited penetration depth of NIR laser and easily reoccurrence and metastasis of tumor in the single photothermal therapy（PTT）for tumor treatment,the development of photothermal treatment materials with more safety and efficiency are necessary.The photothermal composite hydrogel platform has the advantages of good biocompatibility,multiple loads and fixed-point slow-release drug delivery,which can improve the bioavailability of drugs and reduce systemic toxicity.Herein,two kinds of photothermal composite hydrogels with high photothermal conversion efficiency are prepared by choosing the gellan gum as gel matrix,and then are applied in tumor treatment.The highlights of the researches are as follows:（1）The as-prepared of Au/MnO₂@GG composite hydrogel by hydrogel template method has a higher photothermal conversion efficiency（71.3%）under an 808 nm laser,which is superior to MnO₂@GG（27.1%）and Au@GG（25.7%）.In addition,the composite hydrogel has ideal photothermal stability,excellent storage stability,preferable shear thinning and self-recovery.The antitumor studies in vitro and in vivo have proved that the Au/MnO₂@GG can ablate primary tumors through NIR-triggered PTT effectively and completely.（2）A biodegradable R848/POM@GG injectable hydrogel platform was prepared by the physical mixing method for the combined photothermal/immunotherapy.The prepared photothermal composite hydrogel of POM@GG has high photothermal conversion efficiency（63.1%）under an 808 nm laser（0.3 W/cm²,10 min）.Moreover,the POM clusters have outstanding photothermal stability in deionized water but pH tunable biodegradability in physiological conditions.The in vivo antitumor experiments presented a high tumor inhibition rate of 99.3%and ignorable lung metastasis in the combined treatment group in the breast cancer model.Additionally,the expression of TNF-α,IL-2 and IL-6 are elevated obviously but IL-10 is suppressed in the PTT/immunotherapy group,which supported the NIR-mediated photothermal tumor ablation and immune activation pathway.