Preparation Of Gold-silver Nanoclusters Composites And Their Research On Fluorescence Detection And Mimic Enzyme

As a new type of fluorescent nanomaterial,gold nanoclusters(Au NCs)have the advantages of easy preparation,easy modification,ultra-small size,large stokes shift,and adjustable fluorescence spectrum compared with traditional fluorescent quantum dots.At present,it has been widely used in the fields of biochemical analysis,environmental detection,medical imaging and tumor treatment.At present,it has been widely used in the fields of biochemical analysis,environmental detection,medical imaging and tumor treatment.The doping of silver can enhance the fluorescence of Au NCs and the gold-silver nanoclusters(Au-Ag NCs)with enhanced fluorescence can be better used for fluorescence sensing,but the problem still faced is:single-intensity fluorescent probes are easily affected by probe concentration or excitation light source.Therefore,it is particularly important to combine Au-Ag NCs with other fluorescent materials to construct a ratiometric fluorescent probe.In addition,because"gold"has good catalytic properties,In addition,because"gold"has good catalytic properties,many gold nanomaterials are used as enzyme mimics.However,there are relatively few studies on using Au-Ag NCs as oxidase-like enzymes,mainly due to the poor catalytic effect of individual nanoclusters.To this end,we will focus on improving the catalytic performance of Au-Ag NCs for the detection of small biological molecules.Based on the above analysis,this article focuses on how to use Au-Ag NCs to construct a ratiometric fluorescent probe to achieve visual detection of copper ions and glutathione;how to enhance the oxidase-like activity of Au-Ag NCs and use it to detect uric acid molecules.The specific research content is as follows:(1)Use high-fluorescence carbon dots(CDs)and Au-Ag NCs to combine,and the two are formed into CDs/Au-Ag NCs composites through the amide bond under the action of the coupling agent.The composites have double fluorescence emission peaks of CDs and Au-Ag NCs.Among them,the fluorescence of the CDs is used as the reference signal,and the fluorescence of the Au-Ag NCs is used as the detection signal.Using copper ions to quench the fluorescence of the Au-Ag NCs,the fluorescence color changes under ultraviolet light irradiation,the visual detection of Cu²⁺can be realized.(2)To further explore the effect of Cu²⁺on the catalytic activity of Au-Ag NCs,gold-silver nanoclusters/copper ion composites were synthesized.Cu²⁺promote the electron transfer on the surface of Au-Ag NCs,which enhances the catalytic activity,so the Au-Ag NCs/Cu²⁺composites can be used as oxidase-like enzymes to oxidize the substrate3,3',5,5'-tetramethylbenzidine(TMB),and the strong reducing properties of uric acid(UA)can reduce the oxidized TMB,turning it from blue to colorless Therefore,the Au-Ag NCs/Cu²⁺composites can be used for colorimetric detection of UA.