Construction Of Collagen Peptide Protected Metal Nanoclusters And Their Application In Sensing Platform

Metal nanoclusters（MNCs）are a new class of nanomaterials protected by ligands with small size,strong photostability,large Stokes shift,good water solubility,tunable photoluminescence,and good biocompatibility.It has attracted great interest from researchers and has been widely used in photoelectrochemical catalysis,food safety detection,biomedical sensing and environmental monitoring.In recent years,metal nanoclusters are often synthesized using proteins and peptides as templates.However,proteins are easily denatured or structurally damaged at high temperatures,resulting in the lack of thermal stability of metal nanoclusters prepared with protein as a template.On the other hand,the synthesis of metal nanoclusters using peptides as templates usually requires the introduction of additional reducing agents,and the high cost of artificial peptide synthesis limits its application range.Therefore,it is very important to find low-cost,green and environmentally friendly materials and use them as templates to construct metal nanoclusters with superior stability.Collagen peptides are mostly obtained by hydrolysis of animal processing wastes such as skin,lin,bone,etc.,with wide sources and low cost.Moreover,collagen peptides are rich in amino acids such as glycine and histidine that can coordinate with metals and have reducing ability.At the same time,collagen peptides have better structural stability at high temperature.Therefore,natural collagen peptides are ideal templates with excellent synthetic properties,low cost and excellent stability.In this paper,using natural collagen peptide as a template,and using it as a protective agent and reducing agent,metal nanoparticles with excellent photothermal stability,high quantum yield and good biocompatibility were synthesized by"one-pot method"and microwave-assisted method.cluster.On this basis,the detection of various targets was further explored,and a sensing system with high selectivity and high sensitivity was established.The main research contents are as follows:（1）Using tilapia scale collagen peptides（TSCPs）as templates,TSCPs-protected gold nanoclusters（Au NCs@TSCP）were prepared by a"one-pot"method,and the effect of Fe³⁺on its fluorescence was explored,and Au NCs@TSCP was constructed.The TSCP-Fe³⁺fluorescence sensing platform was used for the detection of tetracycline（TC）and ciprofloxacin（CIP）.When TC was added,the fluorescence was further quenched;while after CIP was added,the fluorescence was enhanced.Taking advantage of this phenomenon,we achieved highly sensitive and highly specific detection of TC and CIP,and the detection limits of TC and CIP were 32.8 nmol/L and15.68 nmol/L,respectively.In addition,based on this sensing strategy,an inhibitory molecular logic gate with TC and CIP as input and the fluorescence change of Au NCs@TSCP-Fe³⁺as output was constructed.These findings have potential applications in multi-substance intelligent analytical sensing systems.（2）Gold-copper bimetallic nanoclusters（Au/Cu NCs@BSCP）were prepared by microwave heating using bovine bovine collagen peptide（BSCP）as a template,and graphene oxide（GO）was further introduced as a quencher to reduce the background signal.When CIP was added to the Au/Cu NCs@BSCP-GO system,due to the interaction between CIP and GO throughπ-πstacking,GO was separated from Au/Cu NCs@BSCP,and the fluorescence of Au/Cu NCs@BSCP was recovered and significantly enhanced.Using this principle,the Au/Cu NCs@BSCP-GO system was used as a fluorescence turn-on sensor to detect CIP,and the fluorescence sensitization rate of the system showed a good linear relationship with the CIP concentration.The regression equation is:F（%）=5.89 C_CIP（μmol/L）-0.16（R²=0.9999）with a detection limit of 9.68 nmol/L.The results show that the established method has good selectivity and high sensitivity,and can be applied to the detection of CIP in real samples.（3）BSCP-protected gold-silver bimetallic nanoclusters（Au/Ag NCs@BSCP）were prepared by a"one-pot method"using BSCP as a template.On this basis,the introduction of tungsten disulfide（WS₂）as a quencher reduced the fluorescence signal of Au/Ag NCs@BSCP,and based on this,a fluorescence sensing platform of Au/Ag NCs@BSCP-WS₂was constructed for the monitoring of denatured collagen.Using the difference in the binding ability of nanoclusters to native collagen and denatured collagen,the quantitative detection of the degree of collagen denaturation was successfully achieved.Moreover,the fluorescence change rate of the sensing platform has a good linear relationship with the degree of denaturation of collagen samples,and the linear equation is:F（%）=33.80-0.32 D_Col（%）（R²=0.9799）.This method can efficiently and quantitatively detect the degree of collagen degeneration,which provides a new idea for the screening of diseases caused by collagen degeneration,and has broad biomedical application potential.