A Smartphone Colorimetric Sensor Based on Pt@Au Nanozyme for Visual and Quantitative Detection of Omethoate

Abstract

A smartphone colorimetric sensor based on the Pt@Au nanozyme was successfully developed for the visual and quantitative detection of omethoate in fruit and vegetables. The anti-omethoate antibody was conjugated on the surface of the Pt@Au nanozyme as a catalytic functional signal probe, and coating antigen conjugated on the surface of magnetic polystyrene microspheres (MPMs) was used as a separation capture probe. In the sensing system, when the catalytic functional signal probe was combined with a separation capture probe containing no omethoate, the visible blue color appeared with the addition of tetramethylbenzidine (TMB) chromogenic solution, and the maximum B value of the sensing system was obtained via the smartphone. With increasing concentrations of omethoate, the visualization of the sensing system decreased, and the B-value obtained via the smartphone dropped. Under optimal detection conditions, the omethoate could be detected in a linear range of 0.5–50 μg/L (R2 = 0.9965), with a detection limit of 0.01 μg/L. The accuracy and reliability of the detection results of this colorimetric sensor were successfully confirmed by enzyme linked immunosorbent assay (ELISA) and gas chromatography. This colorimetric sensor provides a technical reference and potential strategy for the immunoassay of hazard factors in resource-scarce laboratories.

A pomegranate seed-structured nanozyme-based colorimetric immunoassay for highly sensitive and specific biosensing of Staphylococcus aureus

“…The pomegranate seed-structured bimetallic gold–platinum nanomaterials (Ps-PtAu NPs) were prepared at room temperature according to the previous literature. 31 As shown in Fig. 1A, TEM demonstrated that the synthesized Ps-PtAu NPs had a well-defined spherical pomegranate seed shape with a uniform diameter of around 15.12 ± 1.6 nm (Fig.…”

“…These findings suggested good oxidative mimicking activity of Ps-PtAu NPs. 31 As the concentration of Ps-PtAu NPs co-incubated with TMB increased, obvious and significant enhancement in the UV-vis absorbance spectrum was observed (Fig. 2B).…”

“…Ps-PtAu NP nanozymes were synthesized according to the previous literature. 31 First, HAuCl 4 solution (40 mM, 0.5 mL) and K 2 PtCl 4 solution (40 mM, 4.5 mL) were added into a 25 mL round-bottomed flask. Then, Pluronic F127 (100 mg) was added into the above solution and sonicated for 2 min to fully dissolve it.…”

Rational Integration of Nanozyme Probe and Smartphone Device for On‐Site Analysis

“…Integrated with the smartphone Apps featuring powerful computing and analysis capabilities, the signal intensities could be transferred to the data directly reflecting the analyte concentration. [55][56][57] For example, S. Lee and coworkers reported Fe-doped carbon dots (FeCDs) with peroxidase (POD)-mimic activity, which were further used to establish a portable smartphone-nanopaper integrated sensing platform to monitor hydrogen peroxide (H 2 O 2 ). [49] H 2 O 2 was decomposed into reactive hydroxyl radicals ( * OH) by the FeCDs nanozyme catalysis, which continuously oxidized the colorless TMB to generate a blue oxidization product (oxTMB).…”

“…In addition, the illegal additives such as industrial alcohol, βestradiol, melamine, etc., are also involved in nanozyme-based food analysis. [57,140]…”