Preparation And Applied Technology Research Of Electrochemical Sensors Based On Novel Nanomaterials

A novel electrochemiluminescence?ECL?sensor based prepared nanoparticles and strategies of enhangced signals for detection of some specific harmful micro-substances,such as biological harmful molecules-tetrodotoxin,heavy metal harmful substances-Hg²⁺.Au nanoparticles?AuNPs?,as one of the typical representatives of nanomaterials,have excellent photoelectric properties,large specific surface area,and good biocompatibility.Its covalent bonding with hydroxyl and hydrazine groups also provides a good basis for the preparation of subsequent nanocomposites.Quantum dots?QDs?are also used because of their excellent luminescent properties.In addition,the methods of reducing the distance between the luminophores and the co-reactants,and enhancing the number of luminophores on the electrode surface were carried out in electrochemical sensor construct to enhance the sensitivity for rapid detection of targets.The details were described as follows:1.A label-free self-enhanced electrochemiluminescence immunosensor for ultrasensitive detection of TetrodotoxinA label-free self-enhanced ECL immunosensor based on tris?2,2'-bipyridyl?ruthenium???-Au nanoparticles(Ru?bpy?₃²⁺-AuNPs)composite to coat the glassy carbon electrode?GCE?with Nafion for ultrasensitive detection of tetrodotoxin?TTX?has been developed.In this strategy,anti-TTX was able to be fixed on the electrode surface via Au-N chemical bond for the specificity capture of the target.Meanwhile,TTX could be used as co-reactant to promote the Ru?bpy?₃²⁺-ECL intensity.The advantages of this approach are that the electron transfer distance between the emitter and the co-reactant is shorter and the ECL efficiency is improved compared to the presence of co-reactant in solution.Under the optimum condition,the change of ECL intensity demonstrated a linear relationship with TTX concentration in the range of 0.01¹000 ng·mL^-1 with a limit of detection?LOD?of 0.01 ng·mL^-1?S/N=3?.This label-free self-enhanced ECL immunosensor exhibited excellent performance of stability,reproducibility and sensitivity.2.A Novel Surface-Tethered Electrochemiluminescence Sensor Based on Dual-Potential Between Luminol and CdS quantum dots for Mercury???ion DetectionIt was the first time that a novel electrochemiluminescence?ECL?sensor has been developed for detection of mercury???ion(Hg²⁺)based on dual signal ECL system and surface-tethered ECL enhancing strategy.The sensor used CdS quantum dots and luminol as two signal materials to construct a dual potential system.Cysteamine functionalized CdS quantum dots?CdS QDs-Cys?as one of potential resolved ECL nanoprobes were first dipped on glass carbon electrode?GCE/CdS QDs-Cys?.Simultaneously,we designed luminol@Au-cysteamine-thymine?luminol@Au-Cys-T?multifunctional nanoparticles to act as the other signal units in the experimental process.Through a specific T-Hg²⁺-T coordination,luminol@Au-Cys-T composites were gravitationally self-assembled to the electrode surface to format a staggered nanoarchitecture.It provided two identical signal change-enhanced trend of CdS QDs and luminol when Hg²⁺existed.Under the optimum condition,the change of ECL intensity demonstrated a linear relationship with Hg²⁺concentration variation from 0.005 nmol·L^-1 to 2.5 nmol·L^-1 and a low limit of detection?LOD?down to 0.002nmol·L^-1?S/N=3?.It combined two technical advantages and offered an alternative analytical approach for the following research.3.A Novel Surface-Tethered Analysis Method for Mercury???ion Detection via Self-Assembly of Individual Electrochemiluminescence Signal UnitsA novel analysis method for Mercury???ion(Hg²⁺)detection was proposed that based on the single AIST of ECL signal nanoparticles.In this work,we designed the luminol@Au-Cys-T multifunctional nanoparticles as ECL signal units.The surface of electrode was firstly modified with tris?2-aminoethyl?amine functionalized graphene oxide@perylene-3,4,9,10-tetracarboxylic acid-thymine?GO@PTCA-TAEA-T?composite membrane,then the luminol@Au-Cys-T nanopqrticles was gradually self-assembled onto the electrode by specific T-Hg²⁺-T coordination.This simple AIST strategy of signal molecule could amplify the signal response and greatly increase the sensitivity of the sensor.Under optimal conditions,the ECL signal intensity showed a good linear relationship with Hg²⁺concentration in the range from 0.005 nmol·L^-1 to 5 nmol·L^-1with a detection limit?LOD?of 0.002 nmol·L^-1?S/N=3?.The regression equation was y=-414.52+2305.02 lgC_Hg²⁺.The experimental results showed that this Hg²⁺ECL sensor would have a good application prospect in the analysis of real samples.At the same time,this study provided an alternative analytical method with excellent stability and selectivity.