The Construction Of Nanosensor And Its Application In The Detection Of Heavy Metal Ions And Small Molecules

The vigorous development of nanotechnology has brought nanosensors into a new stage.Semiconductor quantum dots(QDs)have shown broad application prospects in the field of analysis and detection,due to its excellent fluorescence performance,narrow emission peak and symmetry.Gold nanoclusters(AuNCs),as an emerging fluorescent nanomaterial,have received extensive attention in recent years.They have excellent biocompatibility,good optical properties and easy functional modification.Coating metal organic framework material(MOF)on the surface of the gold nanocluster can improve the stability and luminous efficiency of the gold nanoclusters.Therefore,nanomaterials and MOF-coated nanomaterials have been used in many fields,such as water quality monitoring,food testing,body fluid testing,clinical diagnosis,drug delivery,disease diagnosis,cell imaging,in vivo imaging,etc.Based on this,this paper used ZnSe QDs,AuNCs@11-MUA,and AuNCs@ZIF-8 as sensors to study their applications in the detection of heavy metal ions and small molecules.The specific research content is as follows:Chapter 1:The properties,synthesis and applications of semiconductor quantum dots,carbon nanomaterials,precious metal nanomaterials,and metal organic frame-coated nanomaterials in the field of sensing are introduced.Chapter 2:Using N-acetyl-L-cysteine(NAC)as a stabilizer,successfully synthesized NAC-ZnSe QDs by aqueous phase synthesis method,using UV-vis spectra and fluorescence spectroscopy to characterize their optical properties,FT-IR to characterize their surface functional groups,and TEM to characterize their morphology.It shows that NAC-ZnSe QDs with a particle size distribution of 2.3±1.0nm were successfully synthesized.Based on the red shift of the UV-vis spectra of ZnSe QDs by the formation of ZnSe/Cd S QDs in the presence of S^2-and ZnSe QDs,a fast and sensitive detection method of Cd²⁺is realized by using ZnSe QDs as nanosensor.This strategy shows good selectivity for Cd²⁺detection.Based on this strategy,the detection limit of Cd²⁺by ultraviolet-visible spectroscopy is 0.011?M,which is better than the detection limit reported by most nanomaterials.The response time of Cd²⁺detection is as short as 60 s,which is suitable for rapid detection.The ratio sensor can be used for the detection of Cd²⁺in tap water samples,and the recovery rate of Cd²⁺is between 94.9%-105.6%.Chapter 3:Using 11-mercaptoundecanoic acid(11-MUA)as stabilizer and reducing agent,successfully synthesized AuNCs@11-MUA with good optical performance by chemical reduction method,and characterized its optical properties by UV-vis spectra and fluorescence spectroscopy,and FT-IR to characterize its optical properties Surface functional groups were characterized by TEM,and the results showed that AuNCs@11-MUA with a particle size distribution of 1.6±0.7 nm and excellent optical properties were successfully synthesized.Based on the strong binding ability between GSH and Cu²⁺,GSH could recover the fluorescence of AuNCs quenched by Cu²⁺.Thus,this strategy shows good selectivity for GSH detection,the linear range of this detection method is 0.05-5.00?M,and the detection limit is 0.033?M.The detection limit is better than most of the results reported in the literature,and this sensor has the advantages of simple synthesis method.Chapter 4:With AuNCs as the core structure and ZIF-8 as the shell structure,successfully synthesized AuNCs@ZIF-8 with good optical performance through the ship-in-bottled strategy,and characterized by UV-vis spectra and fluorescence spectra to characterize its optical properties,and XRD characterization Its crystal structure,TEM characterizes its morphology,and the results show that AuNCs@ZIF-8 with a particle size distribution of 43.0±17.0 nm,excellent optical properties,and a ZIF-8crystal structure.Based on the aggregation mediated fluorescence quenching of AuNCs@ZIF-8 caused by Cr³⁺,a high-sensitivity detection method of Cr³⁺is establised.The linear range for detecting Cr³⁺is 0.05-8.00?M,and the detection limit is 0.012?M.This detection method can be used to determine the Cr³⁺content in Yongjiang water and tap water.The recovery rate of Cr³⁺in Yongjiang water is between 98.60%-101.06%,and the recovery rate of Cr³⁺in tap water samples is97.96%-107.19%,indicating that the recovery rate is 97.96%-107.19%.This detection method can be used for the detection of actual samples.Chapter 5:Based on the redox reaction between KMn O₄and ascorbic acid(AA),AA could recover the fluorescnece intensity of AuNCs@ZIF-8 quenched by KMn O₄.Thus,a high-sensitivity method for KMn O₄and AA detection is developed by using AuNCs@ZIF-8 as a nanosensor.The linear range of this detection method for detecting KMn O₄is 0.05-2.00?M,and the detection limit is 0.01?M.The linear range of AA detection is 0.05-5.00?M,and the detection limit is 0.037?M.The detection method can be used for the determination of AA content in tablets,and the recovery rate is 103.78%-108.58%,indicating that the detection method can be used for the detection of actual samples.