Construction Of Several Gold-based Nanoprobes And Their Application In Detection Of Small Biological Molecules

The gold nanosensor has been widely applied in food analysis,environment monitor,and disease diagnosis and so on.In this work,we have synthesized several gold nanomaterials for determination of biological small molecules.The main work is as follows:1.A novel nano-sensing platform was designed,It was found that gold nanoparticles（AuNPs）can be used to selectively detect homocysteine（Hcy）in the presence of glutathione（GSH）,and cysteine（Cys）.The mechanism of selective detection of Hcy by AuNPs probe was investigated.The results shown that when Hcy and Cys reacted with AuNPs respectively,the rate of aggregation induction of AuNPs was different due to the difference of hydrogen bond,steric hindrance and carbon chain length between Hcy and Cys,generating different UV signal responses to selectively detect Hcy.Under the best conditions,the sensor exhibited high sensitivity with a linear range from 0.02 to 0.6μM and the low detection was 0.008μM.In addition,experiments have shown that the sensor can be successfully applied to the determination of Hcy in human serum,and the detection results were consistent with clinically determined results by enzymatic methods.2.A fast,green and one pot approach was developed to synthesize AuNCs@ZnGlu-MOF.The AuNCs@ZnGlu-MOF nanocomposites were rapidly prepared in 2 minutes by mixing GSH-protected gold clusters（AuNCs）with sodium glutamate metal organic framework（ZnGlu-MOF）precursors.The experimental results shown that the fluorescence quantum yield of the prepared AuNCs@ZnGlu-MOF composite is 6times that of AuNCs.The AuNCs@ZnGlu-MOF can be designed as fluorescence probe to selectively and sensitively detect H₂O₂ with a linear range from 0.02 to 5μM and the low detection was 0.01μM,which makes Au NCs@ZnGlu-MOF as desirable probe to detect H₂O₂ content in human serum samples.3.A fluorescent probe consisting of upconversion nanoparticles（UCNPs）and gold nanoparticles（AuNPs）was designed.AuNPs and UCNPs can be combined by electrostatic attraction,which leaded to the fluorescence quenching of UCNPs by the energy resonance transfer（FRET）.In the presence of L-cysteine,AuNPs released from the surface of UCNPs,which resulted in the fluorescence recovery of UCNPs.Upon addition of I^-,the fluorescence of UCNPs was quenched gradually in that I^-can catalyze the oxidation of L-cysteine,preventing the aggregation of AuNPs and forming the fluorescence energy resonance transfer system.Based on the above experimental facts,we established a sensitive detection method for I^-.Under the optimal conditions,the sensor allows detect I^-with a linear range from 0.1 to 200μM and the low detection was 55 nM.Furthermore,the sensor proved that it has the potential for the detection of I^-in urine samples.