Multiple Signal Amplified Electrochemiluminescent Immunoassay for Hg²⁺ Using Graphene-Coupled Quantum Dots and Gold Nanoparticles-Labeled Horseradish Peroxidase

Abstract

A multiple signal amplification strategy was designed for an ultrasensitive competitive immunoassay for Hg(2+). This strategy was achieved using graphene conjugated with a large number of CdSe quantum dots to enhance the basal signal and enormous horseradish peroxidase (HRP) labeled with gold nanoparticles (AuNPs) to consume the coreactant H2O2 generated in situ. The immunosensor was constructed by immobilization of coating antigen on poly(diallyldimethylammonium chloride)-graphene-CdSe composites (PDDA-GN-CdSe), and a strong electrochemiluminescence (ECL) signal was obtained. When the immunosensor was immersed in antibody-AuNPs-HRP composites, the ECL signal greatly decreased, which was ascribed to the bound enzyme on the electrode surface. The self-produced coreactant H2O2 was consumed by o-phenylenediamine in the presence of enzyme, effectively decreasing the ECL intensity from the quantum dots. The Hg(2+) in solution and the corresponding coating antigen competed for the limited antibody, and thus, the ECL intensity was linearly dependent on the logarithm of the mercury(II) concentration from 0.2 to 1000 ng mL(-1) with a detection limit of 0.06 ng mL(-1). The immunoassay exhibited good stability and accuracy and acceptable reproducibility, indicating that it provides a promising approach for the detection of trace mercury and other small molecular compounds in environmental samples.

Input of Electroanalytical Methods for the Determination of Diclofenac: A Review of Recent Trends and Developments

“…Recently, electrochemiluminescence (ECL), combining electrochemistry and chemiluminescence analysis, has attracted extensive attentions due to its high sensitivity detection, simplified optical setup and low background noise. [155][156][157][158][159][160] By integrating the specific recognition of immunoassay between antigen and antibody and the properties of ECL, the ECL immunoassay (ECLIA) has become a powerful analytical tool for highly sensitive and specific detection of clinical samples. The ECL intensity mainly depends on the rate of electrochemical reaction, the efficiency of the excited state product and the luminescent efficiency of the excited state material.…”

Aptamer-Conjugated Quantum Dot Optical Biosensors: Strategies and Applications

“…As a QD quencher, horseradish peroxidase (HRP) has been used to detect chloramphenicol [47]; Figure 3A. In order to immobilize CdS QD on the GCE, GOx was positively charged by treatment with polydiallyldimethylammonium chloride (PDDA) [74], which functioned as a linker. GOx could bind with CdS QD through electrostatic interactions and then the GOx-QD composite could be adsorbed onto the GCE.…”

A Novel Surface‐tethered Analysis Method for Mercury (II) ion Detection via Self‐assembly of Individual Electrochemiluminescence Signal Units

“…It always causes poisoning for humans through damaging the brain, immune system, and other organs . Based on these significant health issues, various methods have been applied to identify and quantify Hg 2+ , including colorimetric strategy , fluorescence strategy , electrochemical strategy , electrochemiluminescence strategy and so forth. Although these methods have well showed the ability to detect Hg 2+ , they still have the disadvantages such as high LOD, expensive equipment and materials, and complicated operation.…”