Electrochemiluminescent Quenching of Quantum Dots for Ultrasensitive Immunoassay through Oxygen Reduction Catalyzed by Nitrogen-Doped Graphene-Supported Hemin

Abstract

A hemin functionalized graphene sheet was prepared via the noncovalent assembly of hemin on nitrogen-doped graphene. The graphene sheet could act as an oxygen reduction catalyst to produce sensitive electrochemiluminescent (ECL) quenching of quantum dots (QDs) due to the annihilation of dissolved oxygen, the ECL coreactant, by its electrocatalytic reduction. With the use of the catalyst with high loading of hemin as a signal tag of the secondary antibody, a novel ultrasensitive immunoassay method for biomarker detection was proposed. In an air-saturated pH 8.0 buffer, the immunosensor constructed by a stepwise immobilization of bidentate-chelated CdTe QDs and capture antibody showed an intensive cathodic ECL irradiation, which could be scavenged upon the formation of the catalyst-bound sandwich immunocomplex. With the use of the carcinoembryonic antigen as a model analyte, the immunoassay method showed a linear range from 0.1 pg mL(-1) to 10 ng mL(-1) and a detection limit of 24 fg mL(-1). The immunosensor exhibited good stability, acceptable fabrication reproducibility, and practicability. The electrocatalytic reduction-based ECL quenching strategy provided a powerful avenue for the design of the ultrasensitive detection method, showing great promise for clinical application.

Cathodic electrochemiluminescence of meso-tetra(4-carboxyphenyl) porphyrin/potassium peroxydisulfate system in aqueous media

“…So it has now become a very powerful tool for medical diagnostics [2], detection of food [3,4] and water [5], immunoassay [6] and biowarfare agent detection [7,8]. Up to now, ECL luminophores which have been found are mainly tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy) 3 2+ ) [4,[9][10][11][12], luminol [13][14][15][16], lucigenin [17][18][19], acridinium esters [20,21], 9,10-diphenylanthracene (DPA) [10,22,23], semiconductor nanomaterial [24][25][26]. It is imperative to find new luminophore for the development and application of ECL.…”

Signal Amplification for Highly Sensitive Immunosensing

“…Ju's group [49] also prepared a hemin functionalized graphene sheet via the noncovalent assembly of hemin on nitrogen-doped grapheme (NG). The hemin@NG could act as an oxygen reduction catalyst to produce sensitive ECL quenching of quantum dots (QDs) due to the annihilation of dissolved oxygen, the ECL coreactant, by its electrocatalytic reduction.…”

Target-assistant Zn2+-dependent DNAzyme for signal-on electrochemiluminescent biosensing

“…In particular, quantum dots (QDs) based ECL presents an excellent prospect in detection of cells, proteins, DNAs, small biological molecules and metal ions [9][10][11][12][13][14]. The traditional ECL sensors are mainly based on three mechanisms: steric hindrance, generation/consumption of coreactant and resonance energy transfer [15][16][17][18][19][20][21]. Resonance energy transfer (RET) of luminol-CdSe/ZnS QDs conjugates have been applied in constructing ECL platform to monitor both conformational change of proteins and interaction between proteins [20].…”

“…Resonance energy transfer (RET) of luminol-CdSe/ZnS QDs conjugates have been applied in constructing ECL platform to monitor both conformational change of proteins and interaction between proteins [20]. A sensitive immunoassay method for biomarker detection was proposed based on ECL quenching of QDs through the annihilation of dissolved oxygen catalyzed by nitrogen-doped graphenesupported hemin [21]. However, the single quenching mechanism may easily be influenced by the complex environment of the real sample and lower the detection accuracy.…”