Application Of Two-dimensional MXene Composite Material Loaded With Carbon Dots In Synergistic Treatment Of Photothermal Ablation And Chemotherapy

Today,although people have put a lot of effort in the treatment of cancer,cancer is still one of the great threats to the health of all humans.With the development of medicine and materials science,photothermal therapy（PTT）has been widely concerned for its noninvasive characteristics.Tumor cells killing is achieved using the heat produced upon PTA exposure to the near-infrared radiation（NIR）,which has the advantages of low cost,high efficiency and minimally invasive.The PTA used in traditional PTT usually completes the photothermal conversion process in the biological window of NIR-I,and it is often difficult to penetrate deep biological tissues.Thereby reducing the therapeutic effect.Therefore,PTA with a longer wavelength in NIR-II biological window have been discovered,which can improve the penetration efficiency of NIR laser while reducing tissue self-heating to achieve more effective photothermal ablation of tumors.Two-dimensional transition metal carbide（MXenes）is a novel two-dimensional layered material with unique frame structure,high specific surface area and active surface sites,which has a very broad prospect in the photothermal treatment of cancer because of the high spectral band and high photothermal conversion efficiency from the UV to the NIR region.Carbon quantum dots are a kind of zero-dimensional carbonaceous nanomaterial,which have been extensively studied due to their good water solubility,low toxicity and biocompatibility.In this article,we synthesized a two-dimensional transition metal material titanium carbide（Ti₂C₃）and modified the carbon dots on the surface of Ti₂C₃.The prepared composite material exhibits excellent photothermal-conversion capability in the NIR-Ⅱbiological window.After that Dox is successfully loaded on the composite material to enable it to be effectively released to perform synergistic photothermal ablation and chemotherapy of cancer.The main research content of this article includes the following aspects:1.Ti₂C₃ MXenes was prepared by two-step liquid-phase acid etching and stripping method,then the carbon dots with positive charge was modified on the surface of MXenes.The absorption of the composite material at NIR-Ⅱregion was significantly enhanced.The extinction coefficient of the composite material was 11.34 L g^-1cm^-1,and the photothermal conversion efficiency reached 59.6%.At the same time,the heating curve shows that the temperature of 300μg m L^-1 solution can reached 52.6℃after 5min laser irradiation.After that,it was found that the tumor cells could be effectively inhibited through the evaluation of cytotoxicity and the photothermal experiment.Furthermore,by intravenously injecting the composite material into mice and performing photothermal treatment,the tumor can be effectively inhibited or even eliminated.2.The chemotherapy drug doxorubicin（DOX）was further loaded onto the surface of the composite material,and the loading efficiency of doxorubicin was 167.3%.The in vitro release of doxorubicin was tested under the conditions of weak acid and laser irradiation in the NIR-II region（1064 nm）,and the release rate of doxorubicin reached 74.3%.Furthermore,the accumulation of adriamycin in nucleus and cytoplasm was observed by confocal microscopy.Subsequently,the composite material was injected intravenously into the mouse and a lower power laser was applied.It was found that low-power mode photothermal synergistic chemotherapy can effectively inhibit tumor growth.Through histopathological examination and blood biochemical analysis,it was found that composite nanomaterials have high biological safety.This showed that the effective release of doxorubicin under high temperature and acidic environment resulting in improved the treatment efficiency and reduces systemic side effects.