Study On The Construction Of Several Novel Optical Chemical Sensors For Small Molecules And Ions Detection

Biosensor analysis has the advantages of high efficiency,fast,controllable cost and high selectivity.It has been widely used in chemical and biological fields.Due to its unique quantum size effect,surface effect and macroscopic quantum tunneling effect,nano-materials have been developed rapidly in the fields of light,electricity and catalysis,and have been widely used in biosensing,and have a good application prospect.This also makes life science,medical development.In this paper,the properties and applications of some nanomaterials were studied in detail,and a series of simple,sensitive and low-cost nano-biosensors were designed for the detection of lactate,ascorbic acid,biothiols and so on.The main contents are as follows:（1）In this paper,the colorimetric sensing of H₂O₂ related molecules and biothiols based on etching and anti-etching strategy was firstly proposed.Ag/carbon nanocomposite（Ag/C NC）was served as the sensing nanoprobe,which was synthesized via carbon dots（C-dots）as the reductant and stabilizer.The characteristic surface plasmon resonance absorption of the Ag nanoparticles（AgNPs）responds sensitively to the amount of H₂O₂ and accompanies the change of the solution color from yellow to colorless.which is resulted from the etching of Ag by H₂O₂.The linear range of H₂O₂ detection was 0.1-80 μM and 80-220 μM,and the detection limit was as low as 0.03 μM.At the same time,the sensor platform can be further expanded to detect H₂O₂ related molecules,such as the use of lactic acid enzyme specific reaction of lactic acid to produce H₂O₂,which can achieve indirect detection of lactic acid.The presence of biothiols inhibits H₂O₂ etching.This strategy responds well to the detection of several typical bio-thiols such as Cys,Hcy,and GSH.Therefore,this paper proposes a simple colorimetric strategy for continuous detection of H₂O₂ and bio-mercaptans.（2）Fluorescent nanoprobes often construct sensitive sensors by turn on or turn off strategies.This paper reports for the first time a new strategy for ultrasensitive detection of I-based fluorescence enhancement of Ag⁺-regulated gold nanoclusters（AuNCs）as a closed nanoplatform.In the presence of Ag⁺,the fluorescence intensity of gold nanoclusters（AuNCs）was significantly enhanced.When iodide（I-）is added to Ag⁺-AuNCs,Ag⁺ is detached from AuNCs and bound to I-to quench fluorescence.Compared with the action of I-direct and AuNCs,the addition of Ag⁺ increases the fluorescence quenching efficiency from 32%to 66%,since I’ can act on both Ag⁺ and AuNCs.Therefore,the nanocluster sensing platform based on fluorescence enhancement and fluorescence quenching can be used for the detection of Ag⁺ and I-,respectively.Among them,the detection range and detection limit of Ag⁺were 0.2-12 μM and 0.06 μM,respectively.The detection range and detection limit of I-were 0.001-6 μM and 0.3 nM,respectively.（3）Using the peroxidase-like activity of prussian blue nanocubes（PB NCs）,a simple colorimetric sensor for the detection of alkaline phosphatase（ALP）activity was constructed.PB NCs have peroxidase-like activity.In the presence of H₂O₂,PB NCs can catalyze the oxidation of 3,3,5,5-tetramethylbenzidine（TMB）accompanied by changes in solution color from colorless to blue.Once ascorbic acid（AA）is introduced,PB NCs is reduced to Prussian white（PW）,and PB-like peroxidase activity is inhibited.Inspired by ALP hydrolysis of AAP（ascorbyl phosphate）into AA,a method for sensitive detection of ALP based on PB NCs was developed for the first time.The system has high sensitivity for the detection of ALP activity and the detection limit is as low as 0.3 U/L.