Highly Sensitive Photoelectrochemical Immunoassay with Enhanced Amplification Using Horseradish Peroxidase Induced Biocatalytic Precipitation on a CdS Quantum Dots Multilayer Electrode

Abstract

Herein we demonstrate the protocol of a biocatalytic precipitation (BCP)-based sandwich photoelectrochemical (PEC) horseradish peroxidase (HRP)-linked immunoassay on the basis of their synergy effect for the ultrasensitive detection of mouse IgG (antigen, Ag) as a model protein. The hybrid film consisting of oppositely charged polyelectrolytes and CdS quantum dots (QDs) is developed by the classic layer by layer (LbL) method and then employed as the photoactive antibody (Ab) immobilization matrix for the subsequent sandwich-type Ab-Ag affinity interactions. Improved sensitivity is achieved through using the bioconjugates of HRP-secondary antibodies (Ab(2)). In addition to the much enhanced steric hindrance compared with the original one, the presence of HRP would further stimulate the BCP onto the electrode surface for signal amplification, concomitant to a competitive nonproductive absorption that lowers the photocurrent intensity. As a result of the multisignal amplification in this HRP catalyzed BCP-based PEC immunoassay, it possesses excellent analytical performance. The antigen could be detected from 0.5 pg/mL to 5.0 ng/mL with a detection limit of 0.5 pg/mL.

Highly sensitive and selective photoelectrochemical DNA sensor for the detection of Hg2+ in aqueous solutions

“…Because it can use low-powered light source and simple electronic circuit, the instrumentation cost is very low. Not surprisingly, photoelectrochemical biosensors for DNA damage, DNA hybridization and immunoassays have advanced rapidly in recent years (Haddour et al, 2006;Liang and Guo, 2007;Liang et al, 2006;Okamoto et al, 2005;Tokudome et al, 2005;Zhang et al, 2011;Zhao et al, 2012;Zhao et al, 2011). In comparison, photoelectrochemical detection of small molecules has been rare (Chamier et al, 2010;Zhang et al, 2010b).…”

Quantum dot-based photoelectric conversion for biosensing applications

“…Xu's group reported an amplified PEC immunoassay based on QDs with the integration of horseradish peroxidase (HRP) catalyzed biocatalytic precipitation (BCP) [80]. Compared with the traditional PEC immunosensing strategy for enhanced steric hindrances for signal variation, the use of the complex of HRP-linked secondary antibodies (HRP-Ab 2 ) not only provided the signal changes from steric hindrance, but also stimulated the BCP and thus realized signal amplification (Fig.…”

Ultrasensitive photoelectrochemical immunoassay through tag induced exciton trapping

“…Owing to the separation of excitation signal and detection signal, PEC sensing strategy has plenty of advantages such as low background, low potential different from electrochemiluminescence analysis, which leads to a good analytical performance. Moreover, this strategy can be very easily combined with general immunosensing methods for highly sensitive immunoassay of biomarkers [22][23][24].…”