Fluorescent Gold Nanoclusters For Quantitative Determination Of Chlortetracycline Hydrochloride And Alkaline Phosphatase

Fluorescent gold nanoclusters(Au NCs),as a new type of fluorescent nanomaterials,are widely used in the fields of analytical detection,disease diagnosis,and bioimaging.Since the introduction of antibiotics,they have made great contributions to human beings to fight against diseases,,aureomycin hydrochloride(CTC)has a well-known broad-spectrum antibacterial activity with high water solubility and long environmental half-life,a large amount of CTC is easily concentrated in the aquatic environment,thus causing long-term environmental damage and the emergence of drug-resistant microorganisms,research to explore a sensitive and simple CTC detection method is of great significance.Alkaline phosphatase(ALP)is involved in almost all physiological processes and plays a key role in the regulation of many diseases,and can be used as an important biomarker for the diagnosis of these diseases,so the research and development of assays for ALP is of great importance in clinical diagnosis and treatment.In this paper,Au NCs were prepared using peptides with both stabilizing and reducing properties as templates,and the effects of peptide ligands on the physicochemical properties of Au NCs were investigated,and further quantitative assays for the determination of chrysomycin hydrochloride(CTC)and alkaline phosphatase(ALP)were performed using the prepared Au NCs.The specific studies are as follows:(1)A series of peptide ligands(CCYFFKGGaa,CCYp FFKGGaa,CCYKGGaa,CYFFKGGaa)with both reduction and stability were designed and synthesized,and the effects of the peptide ligands on the physicochemical properties of Au NCs were comparatively investigated based on the optimization of the synthesis conditions such as the molar ratio of peptide and chloroauric acid,reaction time and p H of the system.It was confirmed that the structure of ligand molecules has an important influence on the fluorescence properties of Au NCs,and the fluorescence properties of Au NCs can be regulated by optimizing the design of ligands.The electron-rich phosphate group can enhance the electron transfer ability of the ligand to the metal and enhance the fluorescence intensity of Au NCs;the phenylalanine(F)with aromatic ring structure can enhance the electron transfer ability of the ligand throughπ-πelectron stacking between the ligand molecules and thus enhance the fluorescence intensity of Au NCs;in addition,the amount of cysteine(C)can also regulate the reduction ability and stability of the ligand In addition,the amount of cysteine(C)can also regulate the reducing and stabilizing ability of the ligand,which in turn affects the fluorescent properties of Au NCs.(2)A ratiometric fluorescence method based on the fluorescence shift of Au NCs was established for the rapid and sensitive quantitative detection of CTCs.After adding CTC to Au NCs,a new fluorescence peak is generated at 420 nm in addition to the fluorescence peak of Au NCs at 695 nm.This is due to the fact that the introduction of CTC causes a change in the composition of the Au NCs and generates a new fluorescence peak.The results confirmed that the ratio of fluorescence intensity(F420/F695)was linearly related to the concentration of CTC,with a detection range of 0-8 nmol/m L(R~2=0.999)and a minimum detection limit of 103 n M(S/N=3).Compared with other reported detection methods,the present method is more stable with better linearity,and was successfully applied to the detection in real samples.(3)A ratiometric fluorescence method based on the internal filtration effect(IFE)was developed for the quantitative detection of ALP.This method utilizes the IFE between two fluorescence emission peaks of CTC-Au NCs and p-nitrophenol(PNP).ALP can catalyze the hydrolysis of the substrate p-nitrophenyl disodium phosphate(PNPP)to produce PNP,and the absorption spectrum of PNP overlaps with the fluorescence emission spectrum of CTC-Au NCs near 420 nm,and PNP quenches the fluorescence emission peak of CTC-Au NCs at The fluorescence emission peak at 420nm was quenched by PNP,while the fluorescence peak at 695 nm remained almost unchanged,so the fluorescence peak at 695 nm was used as a reference to establish a ratiometric fluorescence detection method.The results confirmed that the fluorescence intensity ratio of CTC-Au NCs(F420/F695)showed a linear relationship with ALP activity,with a detection range between 0-40 U/L(R~2=0.994)and a minimum detection limit of 0.034 U/L(S/N=3).This method was successfully applied to the detection of serum samples and the study of inhibitors,providing a new avenue for clinical detection studies of ALP.