Ultrasensitive Immunoassay of Protein Biomarker Based on Electrochemiluminescent Quenching of Quantum Dots by Hemin Bio-Bar-Coded Nanoparticle Tags

Abstract

A hemin bio-bar-coded nanoparticle probe labeled antibody was designed by the assembly of antibody and alkylthiol-capped bar-code G-quadruplex DNA on gold nanoparticles and the interaction of hemin with the DNA to form a G-quadruplex/hemin bio-bar-code. An ultrasensitive immunoassay method was developed by combining the labeled antibody with an electrochemiluminescent (ECL) immunosensor for protein. The ECL immunosensor was constructed by a layer-by-layer modification of carbon nanotubes, CdS quantum dots (QDs), and capture antibody on a glassy carbon electrode. In air-saturated pH 8.0 PBS the immunosensor showed a carbon-nanotube-enhanced cathodic ECL emission of QDs. Upon the formation of immunocomplex, the ECL intensity decreased owing to the consumption of ECL coreactant in bio-bar-code electrocatalyzed reduction of dissolved oxygen. Using α-fetoprotein as model analyte, the quenched ECL could be used for immunoassay with a linear range of 0.01 pg mL(-1) to 1 ng mL(-1) and a detection limit of 1.0 fg mL(-1). The wide detection range and high sensitivity resulted from the enhanced ECL emission and highly efficient catalysis of the bio-bar-code. The immunosensor exhibited good stability and acceptable fabrication reproducibility and accuracy, showing great promise for clinical application.

Carbohydrate-based electrochemical biosensor for detection of a cancer biomarker in human plasma

“…However, biosensors designed for the detection of cancer biomarkers of clinical interest are quasi-exclusively immunosensors (Wang et al, 2008;Jie et al, 2010;Lin et al, 2011;Zhang et al, 2012;Hao et al, 2012;Tang et al, 2014;Ali et al, 2015;, which could be cost-effective for some of them. Despite the fact that our F6P-biosensor uses affordable reagents for its design, its sensing performances are remarkably high when compared to reported electrochemical immunosensors in term of LD and linear range (Table 1).…”

“…Biosensor technology has the potential to provide fast and accurate detection of cancer biomarkers (Bohunicky and Mousa, 2010;Chikkaveeraiah et al, 2012;Li et al, 2012;Tothill, 2009;Yang et al, 2014). Among the numerous devices reported, electrochemical biosensors are known to display excellent sensing performances with low detection limits (LD) in the picomolar or femtomolar ranges, notably when associated with electrochemiluminescence (ECL) (Hao et al, 2012;Jie et al, 2010;Lin et al, 2011;Zhang et al, 2012) or electrochemical impedance spectroscopy (EIS) (Li et al, 2005a(Li et al, , 2005bDong et al, 2006;D. Wang et al, 2015) as detection methods.…”

Intercalation of quantum dots as the new signal acquisition and amplification platform for sensitive electrochemiluminescent detection of microRNA

“…Among the popular nanomaterials, semiconductive quantum dots (QDs) have emerged as excellent candidates in biosensor applications attributing to their specific optical and EC properties, which can act as signal tags to trace the recognition events through the target-induced fluorescent or ECL emission variation, or the current change of the metal ions released from the acid-dissolved QDs [24]. Generally speaking, the signal acquisition is accomplished by chemical modification of capture probes with QDs [27][28][29], or the formation of a QDs-containing film on the electrode surface [31][32][33]. However, a laborious and tedious labeling processes for covalent cross-linking of biomolecules and QDs are required in the former method, and easy leakage of QDs from its composited film makes the latter method inaccurate.…”

DNAzyme-Functionalized Gold Nanoparticles for Biosensing

“…In the former case, nucleic acid cleaving or ligating DNAzymes [3,4,165] are used to recognize specific cofactors such as metal ions and small organic molecules; then the DNAzyme-catalyzed cleavage or ligation of the nucleic acid substrates alters AuNP assemblies, producing physically detectable signal changes for sensing the cofactors as targets [194, 241-252, 255-261, 263, 265-267, 269, 271-275, 277, 278]. In the latter case, peroxidase-mimicking DNAzymes [28,29,40,169], usually containing G-quadruplex motifs, serve as signal generators or enhancers on AuNPs to transform target recognition by other molecules into physically detectable signals [221,253,254,262,264,268,270,275,276].…”

“…By functionalizing AuNPs with both DNAzymes and antibodies, sandwich immunoassays were successfully achieved using the DNAzymes on AuNPs to generate color [254], electrochemiluminescence (Fig. 8c) [262], and chemiluminescence [264] signals for the detection of afetoprotein and carcinoembryonic antigen. Pb 2+ detection using Pb 2+ -specific DNAzymes [275] or Pb 2+ -binding G-quarduplex [270] and AuNPs as carriers for peroxidase-mimicking DNAzymes were also achieved by electrochemistry [275] and fluorescence [270] measurements.…”