Gold Nanorods With Different Aspect Ratio For Phototherapy Cancer Treatment

At present,cancer is still one of the most serious public health problems facing today.There are many disadvantages of existing traditional treatment methods such as large trauma of surgical treatment,strong side effects of chemotherapy,and high lethality of radiotherapy on normal tissues.Phototherapy(photothermal and photodynamic therapy)that has emerged in recent years has the advantages of less trauma,strong specificity,and accurate prognosis,and has broad application prospects.Among many phototherapy reagents,gold nanorods(Au NRs)have become the most widely used nanoparticles due to their good biocompatibility and the ability to use near-infrared light from a biosafety optical window to produce phototherapy effects.In this study,we used the seed-mediated growth method,in the presence of the shape-oriented surfactant CTAB,by adjusting the amount of silver nitrate solution added,Au NRs 1～6 with different longitudinal LSPR and different surface charges due to different aspect ratios can be obtained.Through non-biological condition experiments and cell experiments,we established the corresponding relationship between the surface charge of Au NRs and the uptake of Au NRs by cells and the effect of phototherapy: 1)Because the cell surface is negatively charged,the CTAB in Au NRs forms a double-layer structure with the charged head base facing outward,which makes Au NRs surface positively charged.Au NRs with different aspect ratios carry different amounts of positive charges,which affect the internalization ability of the cells to Au NRs.Our study found that when the aspect ratio of Au NRs is 3.6,the amount of Au NRs uptake by 4T1 cells is the largest;2)The aspect ratio of Au NRs has little effect on its photothermal effect,but when the aspect ratio of Au NRs is 3.6,the best photodynamic effect can be produced;3)Under the synergistic effect of the optimal cell uptake and the best photodynamic therapy effect,Au NRs with an aspect ratio of 3.6 up-regulate the expression of HO-1 and HSP 70 proteins on4T1 cells to produce the strongest phototherapy killing effect.And through the evaluation of the molecular mechanism of cell damage further proves that Au NRs 1～6 can cause different degrees of cell damage,which lays a certain foundation for the further clinical application of Au NRs.This proves the effectiveness of Au NRs in the photodynamic and photothermal treatment of cancer,and showed great potential in practical applications.