Preparation Of NCeO₂/Au Nanomaterials And Their Anti-melanoma Activity

Melanoma has been one of the most common and fatal diseases in the world.In this regard,the development of the most benevolent treatments,at the same time effectively fighting cancer cells,remains a pressing issue.In recent years,the development of nanoscience and photocatalytic disciplines has provided new ideas for the treatment of melanoma.In the field of photocatalysis,cerium oxide nanoparticles（CNPs）have been commonly used as photocatalysts to generate reactive oxygen species（ROS）under the excitation of ultraviolet light thus achieving degradation of pollutants.CNPs have showed toxicity to cancer cells and provided reliable antioxidant protection to healthy cells,which were due to the presence of both Ce⁴⁺and Ce³⁺valence states on their surfaces and their interconversion.The compounding of CNPs with gold nanoparticles（Au NPs）could enhanced the visible light absorption of CNPs by taking advantage of the surface plasmon resonance（LSPR）effect of Au NPs to improve the photocatalytic ability and thus achieved the effect of cancer treatment.In this study,cerium oxide nanoparticles（n Ce O₂）were first prepared by hydrothermal method,and then Au NPs were compounded with n Ce O₂ by precipitation deposition to form cerium oxide/gold nanocomposites（n Ce O₂/Au）.The n Ce O₂ with a diameter of about 5 nm has been successfully synthesized;when it has compounded with Au NPs,the diameters of both Au NPs and n Ce O₂ have been less than 10 nm.Various characterization methods such as UV spectrophotometer,Raman spectrometer and electrochemical workstation have been used to evaluate the photoelectric properties of the samples.Compared with n Ce O₂,n Ce O₂/Au has had higher visible light absorption and conversion ability,enhanced oxygen vacancy formation,and promoted the production of reactive oxygen species under visible light.In an in vitro cytotoxicity assay,n Ce O₂/Au has showed cytotoxicity to melanoma cells（B16）at a range of concentrations（160μg/m L）under visible light,while Survival rate of normal fibroblasts（3T3）is above 80%.When co-cultured with B16 cells,n Ce O₂/Au has entered the cells and produced ROS（36.63%）under visible light irradiation and further reduced the mitochondrial membrane potential,caused mitochondrial functional damage,and the damaged mitochondria has contributed to apoptosis.Combined with the Annexin V-FITC/PI double staining analysis,it has been confirmed that n Ce O₂/Au has caused apoptosis in B16 cells.Finally,in the in vivo experiments,n Ce O₂/Au nanoparticles have injected intratumorally,and it has found that the n Ce O₂/Au has significantly inhibited tumor growth under visible light irradiation;the mice has showed no significant changes in body weight and normal HE staining histology of major organs,indicating that the photocatalytic effect based on n Ce O₂/Au nanoparticles have had no side effects on the mice themselves.In short,in this work,n Ce O₂/Au has exhibited excellent anti-tumor ability under visible light.This paper provides a potential approach for cancer treatment.