Multifunctional Peroxidase-Encapsulated Nanoliposomes: Bioetching-Induced Photoelectrometric and Colorimetric Immunoassay for Broad-Spectrum Detection of Ochratoxins

Abstract

In this study, a versatile dual-modal readout immunoassay platform was achieved for sensitive and broad-spectrum detection of ochratoxins based on the photocurrent response of flexible CdS/ZnO nanorod arrays/reduced graphene oxide and the localized surface plasmon resonance (LSPR) peak shift of Au nanobipyramids (Au NBPs). By using nanoliposomes as the vehicle to carry the secondary antibody and encapsulate horseradish peroxidase (HRP), the photocurrent change and the peak shift can be greatly amplified. The reaction mechanism was investigated in detail, indicating that HRP can trigger enzymatic bioetching in the presence of H2O2. In the photoelectrochemical detection, the oxidized HRP can etch CdS on the photoelectrode, resulting in the photocurrent change, while in the colorimetric detection, HRP can oxidize H2O2 to produce hydroxyl radicals that can etch Au NBPs to form multiple color changes and LSPR shifts. Compared with the common single-modal immunoassay for ochratoxins, such dual-modal immunoassay is more precise and reliable, owing to the completely independent signal conversion and transmission mechanism. Therefore, we hope that this accurate, simple, and visualized strategy may create a new avenue and provide innovative inspiration for food analysis.

Plasmonic gold nanostructures for biosensing and bioimaging

“…Additionally, Au nanobipyramids (AuNBPs) with sharp edges are expected to be ideal colorful chromogenic substrates due to their high sensitivity to refractive index. Based on the LSPR peak shift of AuNBPs that have a standard bipyramid shape with a brown color and the photocurrent response of flexible reduced graphene oxide or CdS/ZnO NR arrays, Wei et al [ 28 ] developed a dual-modality readout immunoassay platform for the broad-spectrum and sensitive determination of ochratoxin (Fig. 2D ).…”

Advances in Visual Immunoassays for Sensitive Detection of Mycotoxins in Food—A Review

“…Typically, by using the changed multiple color and LSPR shifts of Au nanobipyramids etched by •OH generated from HRP-catalyzed H 2 O 2 , and the changed photocurrent of CdS etched by the oxidized HRP. Wei et al [80] developed an improved colorimetric and photoelectrometric immunoassay for ochratoxins (Figure 2C). The nanoliposomes as the vehicle for carrying more secondary antibodies and encapsulating HRP significantly amplified the detection signal, realizing the simultaneous detection of three ochratoxins (OTA, OTB, and OTC).…”

“…For example, Xu et al [100] developed an indirect competitive MOFs -linked immunosorbent assay for the high throughput and sensitive detection of AFB1 in grain Reprinted from ref. [80]. Copyright 2019 American Chemical Society.…”

“Dual-Signal-On” Integrated-Type Biosensor for Portable Detection of miRNA: Cas12a-Induced Photoelectrochemistry and Fluorescence Strategy

“…To improve the accuracy and sensitivity of the detection platform, another individual response signal is clearly necessary . Different signals have completely independent transmission pathways, which can partly correct the errors caused by personnel operation and external condition factors . Therefore, this work intends to construct a dual-mode biosensor for miR-21 detection.…”

“…24 Different signals have completely independent transmission pathways, which can partly correct the errors caused by personnel operation and external condition factors. 25 Therefore, this work intends to construct a dualmode biosensor for miR-21 detection.…”