Double-Enzyme Active Vanadium Nanospheres-Mediated Ratiometric Multicolor Immunosensors for Sensitive Detection of the T-2 Toxin

Abstract

Owing to its high throughput, simplicity, and rapidity, enzyme-linked immunosorbent assay (ELISA) has attracted much attention in the field of immunoassays. However, the traditional ELISA usually affords a single signal readout and the labeling ability of the enzyme used is poor, resulting in low accuracy and a limited detection range. Herein, a vanadium nanospheres (VNSs)-mediated competitive ratio nanozymes-linked immunosorbent assay (VNSs-RNLISA) was created for the sensitive detection of the T-2 toxin (T-2). As the key to the biosensor, the VNSs with superoxide dismutase-like and peroxidase-like dual-enzyme mimetic activities were synthesized by a one-step hydrothermal method, which oxidized 1,1-diphenyl-2-picryl-hydrazyl fading and catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) color development. Therefore, T-2 could not only be qualitatively measured with the naked eye but also be quantitatively evaluated by monitoring the ratio of absorbance at 450 and 517 nm wavelengths. Moreover, the characterization of a VNSs-labeled antibody probe showed strong dual-enzymatic activity, excellent stability, and high affinity with T-2 [the affinity constant (k a) was approximately 1.36 × 108 M–1], which can significantly improve the detection sensitivity. The limit of detection of VNSs-RNLISA was 0.021 ng/mL, which was approximately 27-fold more sensitive than the single signal nanozymes-linked immunosorbent assay (0.561 ng/mL). Besides, the change in the ratio of absorbance (Δ450/Δ517) decreased linearly in a range of 0.22–13.17 ng/mL, outperforming the detection range of a single-mode nano-enzyme-linked immunosorbent assay using TMB by a factor of 1.6 times. Furthermore, the VNSs-RNLISA was successfully used to identify T-2 in maize and oat samples, with recoveries ranging from 84.216 to 125.371%. Overall, this tactic offered a promising platform for the quick detection of T-2 in food and might broaden the application range of the enzyme-linked immunosorbent assay.

Novel Dumbbell-like CeVO4 Carrier-Based Immunochromatographic Assay for Highly Sensitive T-2 Toxin Detection in Food Samples

“…To compare the affinity of Au and CeVO 4 for mAb, we tested the affinity constant ( k a ) with the use of an indirect enzyme-linked immunosorbent assay (ELISA). The k a was calculated using the following equation k a = n − 1 2 ( n [ mAb ] 1 − [ mAb ] 2 ) where k a represents the affinity constant of mAb, n represents the ratio of the two coated antigen quantities ( n > 1), and [mAb] 1 and [mAb] 2 correspond to the mAb molar amounts of the two coated antigen concentrations under their respective OD max /2 absorbance signals …”

“…The k a was calculated using the following equation where k a represents the affinity constant of mAb, n represents the ratio of the two coated antigen quantities (n > 1), and [mAb] 1 and [mAb] 2 correspond to the mAb molar amounts of the two coated antigen concentrations under their respective OD max /2 absorbance signals. 37 Detection of T-2 in Spiked Samples. The samples were treated using earlier techniques.…”

Novel Immunosensor Based on Metal Single-Atom Nanozymes with Enhanced Oxidase-Like Activity for Capsaicin Analysis in Spicy Food

“…Enzyme-linked immunosorbent assay (ELISA) combines the signal amplification of enzymes with the specific affinity of antigens and antibodies, which has the advantages of strong selectivity, high sensitivity, and simple operation. − However, horseradish peroxidase (HRP), which is a core component in traditional ELISAs, has intrinsic shortcomings, such as complex preparation and purification, high costs, and low stability . Moreover, volatile hydrogen peroxide (H 2 O 2 ) requirements may cause instability, high toxicity, and susceptibility to decomposition during long-term storage, which can impact data related to oxidizing chromogenic substrates.…”

A comprehensive exploration of the latest innovations for advancements in enhancing selectivity of nanozymes for theranostic nanoplatforms

“…[4][5][6][7] This characteristic arises from their diverse structures, multiple reactive sites on the surface, abundant redox potential, and non-specific binding to various substrates. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] While their multifunctional enzyme-like properties enable various applications, such as detections, disease therapy, and environmental remediation, [24][25][26][27][28][29][30][31][32][33][34][35][36][37] their non-selective nature poses challenges in certain contexts, particularly for theragnostic nanoplatforms where precise control is crucial. Therefore, the development of more selective nanozymes has become essential to address these limitations and optimize their applications.…”