| Melanoma has been highly resistant to conventional chemotherapy and radiotherapy and has a very low cure rate,therfore effective treatments are eagerly sought by researchers.In recent years,phototherapy with high efficiency,minimally invasive,spatio-temporal selectivity,negligible drug resistance and other advantages has been attracting increasing attention.Photothermal therapy has been widely used in tumor treatment.Mo S2 nanosheets has been commonly used as photothermal agents because of their high photothermal conversion efficiency and strong near-infrared absorption properties.However,it has been limited by a single photothermal treatment alone.As an excellent photocatalyst,nano-Ce O2could generate large amounts of reactive oxygen species（ROS）.Photothermal therapy（PTT）combined with photocatalytic therapy could kill cancer cells more effectively by the high heat generated by photothermal and the abundant active oxygen produced by photocatalytic.In this study,CeO2-MoS2 nanocomposites with heterojunction structure were prepared by two-step hydrothermal method.Ce O2-Mo S2 nanocomposites had stronger near infrared（NIR）absorption capacity and higher photothermal conversion efficiency（51.8%）than n Mo S2 nanosheets.The increase in oxygen vacancy concentration was caused by the compounding of the materials,which promoted ROS generation.The formation of heterojunctions effectively improved the photocatalytic and photothermal properties of Ce O2-Mo S2 nanocomposites.In order to explore the charge transfer mechanism of heterostructures,photoelectric properties and ROS species were tested.The results has demonstrated that the effective separation of photoelectron-hole pairs promoted ROS production,and the species of reactive oxygen species detected included·O2-,H2O2,1O2,etc.In cellular experiments,Ce O2-Mo S2 heterojunction materials has exhibited good biocompatibility in 3T3L1 fibroblasts and B16F10 melanoma cells was effectively killed under NIR irradiation.Meanwhile,the PTT-photocatalytic synergy of Ce O2-Mo S2composites has showed stronger anti-tumor ability compared to the PTT of single n Mo S2and photocatalytic treatment with n Ce O2.To investigate the anti-tumor mechanism of the materials,intracellular reactive oxygen species,mitochondrial membrane potential,cell nuclear structure and apoptosis were tested separately.Under NIR irradiation,plentiful reactive oxygen species（38.47%）and high temperature has generated by Ce O2-Mo S2nanocomposites in B16F10 melanoma cells.On the one hand,the high temperature generated by PTT has directly induced apoptosis;on the other hand,the photocatalytic generation of abundant reactive oxygen species has led to the disruption of mitochondrial membrane structure and activated mitochondria-mediated apoptosis thus inducing nuclear crumpling of cells.The antitumor behavior of Ce O2-Mo S2-NIR was evaluated in a mouse melanoma tumor model,and the mice in this composite group had the smallest tumor volume and presented significantly higher antitumor activity compared to n Mo S2and n Ce O2.In conclusion,the synergistic effect of photocatalysis and PTT treatment of Ce O2-Mo S2nanocomposites has induced apoptosis of cancer cells and had excellent antitumor properties.This study provides a potential strategy for melanoma treatment. |
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