Preparation Of Rhodium-rhenium Nanozyme For Non-Inflammatory Photothermal Therapy Of Tumor

Cancer is one of the major diseases that is difficult to completely cure,which reduces people’s quality of life and even threatens people’s lives and health.For cancer treatment,the current clinical main means are surgical treatment,radiotherapy and chemotherapy.But with the deeper understanding of cancer,the shortcomings and limitations of these treatments are gradually being revealed and reducing the clinical treatment effect of cancer.As an emerging tumor thermal ablation technology,near-infrared light-mediated photothermal therapy（PTT）has attracted great attention due to its advantages of non-invasiveness and laser localization performance.However,the heating temperature of photothermal therapy can usually reach more than 50°C,which makes the tumor coagulate necrosis and at the same time triggers an inflammatory response,and ultimately reduces the efficiency of PTT.Rh nanozymes have multi-enzyme activity and good near-infrared light absorption performance,making them have the potential to be applied to non-inflammatory photothermal therapy of tumors.In order to further improve the catalytic efficiency of Rh nanozymes and alleviate the inflammatory side effects caused by PTT,this work develops RhRe nanozymes with excellent photothermal properties and efficient ROS removal characteristics,which effectively overcomes the inflammation caused by PTT while kill tumors,the main contents are as follows:1)Firstly,the petal-like RhRe nanozyme was synthesized by liquid phase reduction method,and the surface of RhRe nanozyme was modified with mercapto polyethylene glycol（m PEG-SH）,which improved the dispersion and stability of nanonzyme under different dispersion media and p H conditions.X-ray energy spectroscopy（EDS）showed that the two target metal elements were present in the nanozyme with relatively uniform distribution.The inductively coupled plasma-atom emission spectroscopy（ICP-AES）instrument determined the ratio of the two atoms in the synthesized nanozyme was Rh₇₇Re₂₃.RhRe nanozyme had excellent ultraviolet and visible near-infrared absorption performance,up to 43.54%photothermal conversion efficiency and stable photothermal warming effect,which make it can be applied to NIR-induced photothermal ablation of cancer cells.Dissolved oxygen meter experiments showed that RhRe nanozyme can catalyze H₂O₂ into O₂ with CAT mimetic enzyme activity.In vitro clearance ROS experimental results showed that the ABTS?and O₂?^-clearance of RhRe nanozyme were about 69.37%and 89.88%,while the clearance of Rh nanozyme at the same concentration was only 19.30%and 77.61%,indicating that RhRe nanozyme compared with Rh nanozyme with better ABTS?and O₂?^-clearing effect.2)Evaluation of anti-inflammatory and anti-tumor therapy for RhRe nanozyme in vivo and in vitro.RhRe nanozyme have excellent biosafety in vivo and in vitro.It can effectively kill 4T1 tumor cells,protect normal cells from ROS oxidative stress and significantly reduce the level of ROS-induced cellular inflammation.The results of animal experiments showed that the tumor volume of mice decreased,the nuclei of cells shrunk and the cell space increased in the H&E staining of tumor slices,and the positive coloring degree of immunohistochemical staining of inflammatory factors such as tumor necrosis factor-α（TNF-α）was significantly lower than that of the GO control group but close to the negative control after photothermal killing,which suggest that RhRe nanozymes can successfully thermally ablate tumors and alleviate the inflammatory effects caused by thermal injury.RhRe nanozyme provide valuable examples for more effective cancer treatment as well as non-inflammatory PTT.