Label-Free Quantifications of Multiplexed Mycotoxins by G-Quadruplex Based on Photonic Barcodes

Abstract

Multiplexed quantification of mycotoxins is of great significance in food safety. Here, novel photonic crystal (PhC) barcodes with G-quadruplex aptamer encapsulated for label-free multiplex mycotoxins quantification are developed. The probes are immobilized on PhC barcodes to form a molecular beacon (MB), which contains the sequences of mycotoxin aptamers and a Gquadruplex. In the presence of the target, the hairpin structure of MB would open and the region of the G-quadruplex is exposed, which subsequently combines with Thioflavin T (ThT) to produce fluorescence. The relative fluorescence intensity increased as the mycotoxins concentration increased in a linear range from 1.0 pg/ mL to 100 ng/mL. Moreover, the multiplexed mycotoxins quantification could be achieved by tuning the structural color of the PhC barcodes. We demonstrate that this method with high accuracy and specificity for multiplexed detection of mycotoxins, with the sensitivity of the detection as low as 0.70 pg/mL. Our results show that G-quadruplex-encapsulated PhC barcodes offer a novel simple and label-free pathway toward the multiplex screen assay of mycotoxins for food safety.

Chemiluminescent Enzyme Immunoassay and Bioluminescent Enzyme Immunoassay for Tenuazonic Acid Mycotoxin by Exploitation of Nanobody and Nanobody–Nanoluciferase Fusion

“…Therefore, the preparation of nanobodies could provide new detection reagents for immunodetection, and the development of chemiluminescent and bioluminescent assays have great potential application value for original innovation in immunoassay for TeA analysis. The research could be applied for the combination of nanobodies and new functionalized nanoparticles and the development of label-free immunoassays. − …”

Bottom-Up Assembled Photonic Crystals for Structure-Enabled Label-Free Sensing

“…A strategy was proposed and demonstrated using G-quadruplex-encapsulated SPCs for label-free multiplex detection of mycotoxins with LoD reaching as low as 0.7 pg·mL –1 (1 pM). 129 The SPCs serve as a robust encoding carrier, and the decoding process is achieved by G-quadruplex binding with thioflavin (ThT) as an optical fluorescence label ( Figure 10 ). The probes are immobilized on SPCs to form a molecular beacon (MB), which is composed of sequences of mycotoxin aptamers and a G-quadruplex structure.…”

“… Diagram of label-free quantification of mycotoxins by a G-quadruplex structure and aptamer-immobilized SPCs. Reproduced from ref ( 129 ). Copyright 2020 American Chemical Society.…”

“…Compared to the fluorescence label-based HCR method, , the enzyme-free and label-free methods have raised more attention as they could allow bioassays with low cost and high sensitivity. A strategy was proposed and demonstrated using G-quadruplex-encapsulated SPCs for label-free multiplex detection of mycotoxins with LoD reaching as low as 0.7 pg·mL –1 (1 pM) . The SPCs serve as a robust encoding carrier, and the decoding process is achieved by G-quadruplex binding with thioflavin (ThT) as an optical fluorescence label (Figure ).…”

Quantitative Analysis of Structure Color of Photonic Crystal Sensors Based on HSB Color Space

“…Combined with stimuli-responsive materials such as hydrogels, the lattice spacing of PhCs changes with the expansion and contraction of hydrogels, which can realize optical responses to various physicochemical stimuli (temperature, ionic strength, electric field, stretching, or pH). In addition, PhCs-based bioassay technologies include antigen and antibody recognition, protein detection, , biomolecule screening, , DNA detection, real-time monitoring of enzyme activity, biotoxin detection, and cancer cell screening, and other areas also have excellent development potential.…”