Research On The Applications Of Laponite And DNA Structural Materials In Electrochemiluminescence-Based Biosensing

Owing to its intrinsic electro-stimulated sensitivity and spatiotemporal regulability, electrochemiluminescence (ECL) has become a commercialized platform specialized in biomedical analysis and molecular diagnosis. This postgraduate dissertation contains the following three parts about the ECL biosensors of ions, nucleic acids and proteins:Detection of Zinc ion and Zinc Finger Protein (EGR1) Based on Cathodic Electrochemiluminescence of Nanoclay-Supported Porphyrin.In this work, PPⅨ (proto-porphyrin Ⅸ) molecules were adsorbed onto the unilamellar layered double hydroxides-Laponite for aqueous dispersion and high-loading accommodation. The strong coordination between zinc cation and porphine ring of PPIX generated ZnPPIX (Zinc(Ⅱ) proto-porphyrin Ⅸ) whith has intensive ECL emission in dichloromethane with the dissolved oxygen as endogenous coreactant. Inspired by this interaction, a facile solid-state "signal-on" strategy for highly specific ionic sensing was developed which have a sensitive trace detection of Early growth response protein 1. Showing great promise in bioassays of structural Zn(Ⅱ) proteins and zinc finger-binding nucleotides.Groove Binding between Porphyrins and Duplex as Hybrid Electrochemiluminescent Chains for Label-Free DNA Assay. This work proposed a novel and facile label-free strategy through the formation of hybrid ECL assembly for sensitive detection of DNA. The protocol initiates with the modification of with cDNA on AuNPs modified GCE. With the presente of tDNA, the hybridization chain reaction was triggered. As it is reported that porphyrin could intercalate into the grooves of double-stranded DNA (dsDNA) scaffold, multiple ZnPPⅨs as highly efficient ECL individuals converted in situ the porphyrin-dsDNA complex into a hybrid ECL nanochain. Which facilitates a significant ECL signal amplification. The ECL increment was proportional to the concentration of tDNA, thus an ultrasensitive label-free DNA assay was developed with a sub-femtomolar detection limit.Electrochemiluminescence Resonance Energy Transfer between Biobarcode-Templated Silver Nanoclusters and Quantum Dots for Ultrasensitive Immunoassay.An ECL-based immunoassay for the determination of cancer biomarkers was developed by using biobarcode-tethered nucleotide-templated silver nanoclusters (AgNCs) as a tracing tag. The MPA-chelated CdS QD were applied as ECL nanoemitter. A long-range ECL-resonance energy transfer (ERET) triggered between QD as the energy donor and AgNCs as the highly efficient acceptor. After the sandwich-type reaction taken at the sequentially fabricated immunosensor, multiple DNA-protected AgNCs were hybridized with the complementary capture probe (cDNA)-tagged biobarcode, which could greatly quench the ECL emission of QDs. The annihilated ECL intensity was inversely proportional to the concentration of carcinoembryonic antigen (CEA), resulting in an ultrasensitive protein assay with the detection limit as low as sub-picogram per microlitre.