Construction Of Gold Nanocluster Fluorescent Probe And Its Application In Detection

As a new type of fluorescent material,gold nanoclusters(AuNCs)have high quantum yield(QY),photobleaching resistance and stability.The fluorescence of AuNCs is affected by size,and the emission wavelength of AuNCs can be adjusted by adjusting the number of gold atoms of AuNCs.At the same time,compared with quantum dots,the toxicity of AuNCs is greatly reduced,so the scope of application is wider.Due to its excellent photophysical properties,good biocompatibility,effective biopermeability and easy functional modification characteristics,nanoprobes based on AuNCs have a wide range of applications in bioimaging,drug delivery,analytes detection and other fields.When using gold nanoclusters to detect analytes,the interaction between the analyte and the Au nucleus or ligand will cause the valence of the Au nucleus to change,the formation of complexes,the aggregation of clusters or the change of electron flow,which will eventually disturb fluorescence.This article is based on gold nanoclusters to construct fluorescent probes for analytes detection.Mainly include as follows:(1)Detection application of KA-AuNCs fluorescent probeKojic acid was used as a ligand to synthesize Kojic acid-AuNCs(KA-AuNCs)with bright green fluorescence.The complexation of Fe³⁺with the surface ligand of KA-AuNCs,Kojic acid,resulted in nanoclusters forming aggregates and fluorescence quenching.The fluorescence changes from“on”to“off”.The biomolecule Adenosine Triphosphate(ATP)can coordinate with Fe³⁺,so that the agglomerated nanoclusters are redispersed,and the fluorescence turns from“off”to“on”.The“on”and“off”of the fluorescence can be used to detect Fe³⁺and ATP.The AIE effect induced by Pb²⁺will cause the fluorescence of KA-AuNCs to be greatly enhanced,and the degree of increase is related to the concentration of Pb²⁺.Comparing the reactions between AuNCs with different ligands and metal ions.It not only proves that the fluorescence quenching of KA-AuNCs is related to its surface ligand kojic acid,but also proves that the fluorescence quenching induced by KA-AuNCs/Fe³⁺is much higher than other AuNCs/Fe³⁺in the mixed system.(2)Construction and detection application of fluorescent probe KA-AuNCs/BSA-AuNCs with dual emission systemBy mixing Bull Serum Albumin-AuNCs(BSA-AuNCs)with red fluorescence emission and KA-AuNCs with green fluorescence emission and adjusting the ratio between the two,any color between red and green can be obtained.When the volume ratio of KA-AuNCs:BSA-AuNCs is 20:1,the KA-AuNCs/BSA-AuNCs mixed system can show a red-yellow-green color change with the increase of pH at pH=1?2.6.It can be used for naked eye detection of pH.When pH=1.6 and the volume ratio of KA-AuNCs:BSA-AuNCs is 4:1,as the concentration of Pb²⁺increases,the green fluorescence of KA-AuNCs increases due to the AIE effect,while the red fluorescence of BSA-AuNCs remains stable and can show up.It can also show red-yellow-green color changes,and the ratio of green fluorescence to red fluorescence intensity increases with the increase of Pb²⁺concentration,which can realize Pb²⁺detection.