Construction Of Photoelectrochemical And Fluorenscence Sensors Based On Nanomaterials

Nanoparticles attracted much more attention and have been widely applicated in developping photoelectrochemical?PEC?and fluorescence sensors.By using CdS quantum dots,gold nanoparticles and silver nanoparticles hybrid materials,we fabricated mercury ions,copper ions and hydrogen peroxide sensors respectively.The main contents are as follows:1.A PEC sensor for Hg²⁺ was constructed based on the energy transfer between CdS QDs and Au NPs.The multilayer film of CdS QDs modified ITO electrode was prepared by electrostatic interaction.The energy transfer?ET?-based mechanism was successfully applied in the determination of Hg²⁺ under visible light.In the presence of Hg²⁺ ions,Hg²⁺ and two T-rich DNA oligonucleotides could form T-Hg²⁺-T hybrid pairs.With the formation ofhybrid complex,the Au NPs were linked to CdS QDs,rendering the intensity of photocurrent decrease due to the interparticle energy transfer.Under the optimal condition,the concentration of Hg²⁺ ions ranged from 3.0×10-9 to 1.0×10-7 mol/L,the photocurrent decrease was proportional to the Hg²⁺ concentration,with the detection limit of 6.0×10-10 mol/L.2.A highly sensitive and selective PEC sensor for Cu²⁺ ions was constructed based on click chemistry.The click chemistry was firstly introduced into PEC system,realizing the determination of Cu²⁺ with high selectivity.Using the classic amide coupling reaction among amino and carboxyl groups,11-Azido-3,6,9-trioxaundecan-1-amine was immobilized on the surface of the CdS modified electrode.Propargyl-functionalized Au NPs had been modified on the modified ITO electrode through the reaction with azide terminal electrode via Cu+ catalyzed 1,3 dipolar cycloaddition?CuAAC?,which made CdS QDs close to Au NPs,stimulating the excition-plasmon interaction?EPI?,meanwhile,triggering the interparticle energy transfer,leading the decrease of photocurrent to achieve the detection of Cu²⁺.3.A sensitive fluorescence method for H₂O₂ determination was developed based on the pNIPAm-co-AAc/Ag nanohybrid materials.H₂O₂ could effectively oxidize pNIPAm-co-AAc/Ag nanohybrid materials,causing the fluorescence quench of the system,which could be used to develop a simple fluorescence sensor for the detection of H₂O₂.Under the optimized condition,the linear range of the H₂O₂ fluorescence sensor was 3×10-7³×10-6 mol/L.The influence of the interfering species had been studied,the results showed that the uric acid,vitamin C and other interfering species had negligible effect to the fluorescence intensity.