Performance Regulation Of Singlet Oxygen Generation With Luminescent Gold Nanoparticles And Its Application In Photodynamic Therapy

In recent years,luminescent gold nanoparticles?AuNPs,d<3nm?modified by thiolate ligands have attracted considerable interest in the fields of biochemical sensing,bioimaging and disease treatment due to their optical adjustability,surface ligand specificity,stability and biocompatibility.Among them,the use of luminescent AuNPs as photosensitizers to generate singlet oxygen?¹O₂?for photodynamic therapy?PDT?by photosensitization is favored.The physicochemical properties of luminescent AuNPs depend largely on surface chemistry factors,such as surface ligand modification density and molecular structures of surface ligands,however,the effect of surface chemistry on the generation of ¹O₂ by luminescent AuNPs is still unclear.Therefore,it is of great significance to study the effect of surface chemistry on the generation of ¹O₂ by luminescent AuNPs and to control the generation efficiency of luminescent AuNPs photosensitizer ¹O₂ by regulating the surface chemistry of luminescent AuNPs.In this paper,the effects of surface chemistry on the production of ¹O₂ by AuNPs and the regulation of the production of ¹O₂ by AuNPs are investigated.The research contents and results are as follows:Six kinds of water-soluble ultra-small?¹.8 nm?luminescent AuNPs were synthesized by adjusting the reaction ratio between ligand species and Au³⁺.They are:electrically neutral long-chain polyethylene glycol monomethyl ether thiol?CH₃O-PEG-SH?modified 600 nm and 800nm-emitting AuNPs?CH₃O-PEG-AuNPs?,negatively charged long-chain mercaptoethylene glycol carboxyl?HOOC-PEG-SH?modified 600 nm and 800 nm-emitting AuNPs?HOOC-PEG-AuNPs?,685 nm-emitting positively charged short-chain cysteamine?CA?modified AuNPs?CA-AuNPs?and 685 nm-emitting negatively charged short-chain mercaptoacetic acid?TGA?modified AuNPs?TGA-AuNPs?.The results show that,compared with 800 nm PEG-AuNPs,600 nm PEG-AuNPs with high surface ligand modification density can produce ¹O₂more efficiently.In addition,whether long or short chain ligands are used as surface modifiers of AuNPs,higher surface potential AuNPs are more conducive to the generation of ¹O₂.The results of cells cytotoxicity showed that 600 nm-emitting CH₃O-PEG-AuNPs and 685 nm-emitting CA-AuNPs showed good PDT anti-cancer effects in vitro.This study provides a good reference for the design of high-performance water-soluble luminescent AuNPs photosensitizers.Based on the influence of surface potential on the ¹O₂ production of luminescent AuNPs,a method for regulating the ¹O₂ production of luminescent AuNPs was proposed.The electrically neutral 600 nm-emitting CH₃O-PEG-AuNPs was used as the research object.Through the ligand exchange reaction,different molar ratios of CA and TGA to CH₃O-PEG-AuNPs were introduced to change the surface potential,and a series of ultra-small luminescent AuNPs with different potentials were obtained.Studies have shown that as the proportion of introduced CA increases,the surface potential of CH₃O-PEG-AuNPs gradually increases,and its ability to produce ¹O₂ gradually increases.With the increase of the proportion of TGA introduced,the surface potential of CH₃O-PEG-AuNPs gradually decreased,and its ability to produce ¹O₂ gradually weakened.The results of cells cytotoxicity further indicated that the method has a good regulatory effect at the cellular level.Therefore,this study not only synthesized luminescent AuNPs with high efficiency to produce ¹O₂,which as a potential nano-photosensitizer,but also it provides a new strategy for the development and design of fluorescent probes,photosensitizers and integrated nanomaterials based on luminescent AuNPs.