Preparation Of Small Molecule Functionalized Nano-gold And Its Application In Biological Analysis

Nature enzymes,which possess high catalytic activity and high substrate specificity under mild conditions,are truly exquisite biocatalysts mediating every biological process in all living organisms.However,most of them exist in the form of protein,minority are RNA,which still remain valuableness and storage difficulty.Nanozymes overcome these disadvantages,can stay for a long time.Among these nanozymes,gold nanoparticles(AuNPs)is an important kind of nanozymes and a variety of its artificial enzymatic activities have been reported,such as oxidase,peroxidase,and superoxide dismutase.Due to the strong interaction between gold atom and S,N and O,AuNPs can be modified with various compounds,especially the ones with S,N and O.Ligands effect its peroxidase activity much.In this work,the interaction between ligands and peroxidase,ROS scavenging activity of gold had been discussed,as well as the application in detection of occult blood and ROS scavenging.The main research work can be summarized as following:1.As is reported,polypurine modified perAuxidases displayed a remarkable enhancement compared to pyrimidine modified perAuxidases.Purine is rigid ligand and can coordinate with ferrious ions.Besides,AuNPs and Fe2+all possess intrinsic peroxidase-like activity,H2O2 can be absorbed on the surface of AuNPs,the O-O bond of H2O2 is broken up into double hydroxyl radicals,and the hydroxyl radicals produced by AuNPs and Fe2+can be stablized on the surface of AuNPs,which proved the cooperation between DAP-AuNPs and Fe2+.We investigated the enzymatic activity of five purine derivatives capped AuNPs.2,6-Diaminopurine(DAP)capped AuNPs display the best stability and peroxidase activity,can catalyze H2O2 into OH with or without Fe2+in acidic condition,further oxide colorless TMB(3,3',5,5'-tetramethlbenzi-dine)to blue oxTMB.The cooperative system can be applied to measure red blood cells in urine.Generally,there is no or few red blood cells in human urine.The presence of blood in the urine is closely related with serious diseases,for example chronic nephrotic syndrome and urinary system tumors.Compared the commercial urine test paper,the method based on DAP-AuNPs has a good sensitivity and wider quantitative range.2.Melatonin possess excellent antioxidant actvitiy and can scavenge reactive oxygen species(ROS)effectively.In this study,melatonin derivatives containing sulfhydryl groups(Mela)were used as ligands in synthesizing gold nanoclusters(Mela-AuNCs)with excellent stability,dispersion and fluorescence.Mela-AuNCs emits green fluorescence(?=450 nm)after excited by UV light(?=365 nm).Besides,it exhibits favourable ROS scavenging capacity both in buffer and Hela cells.Encouragd by these advantages,Mela-AuNCs is applied to cells imaging and treatment in inflammatory models.