A Sensitive, Point-of-Care Detection of Small Molecules Based on a Portable Barometer: Aflatoxins In Agricultural Products.

Weiqi Zhang,Wenqin Wu,Yizhen Bai,Zhaowei Zhang,Chong Cai,Xiaofeng Hu,Hui Li,Peiwu Li

doi:10.3390/toxins12030158

Weiqi Zhang, Wenqin Wu + Show 6 more

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https://doi.org/10.3390/toxins12030158

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Abstract

Sensitive and point-of-care detection of small toxic molecules plays a key role in food safety. Aflatoxin, a typical small toxic molecule, can cause serious healthcare and economic issues, thereby promoting the development of sensitive and point-of-care detection. Although ELISA is one of the official detection methods, it cannot fill the gap between sensitivity and point-of-care application because it requires a large-scale microplate reader. To employ portable readers in food safety, Pt-catalysis has attracted increasing attention due to its portability and reliability. In this study, we developed a sensitive point-of-care aflatoxin detection (POCAD) method via a portable handheld barometer. We synthesized and characterized Au@PtNPs and Au@PtNPs conjugated with a second antibody (Au@PtNPs-IgG). A competitive immunoassay was established based on the homemade monoclonal antibody against aflatoxins. Au@PtNPs-IgG was used to catalyze the production of O2 from H2O2 in a sealed vessel. The pressure of O2 was then recorded by a handheld barometer. The aflatoxin concentration was inversely proportional to the pressure recorded via the barometer reading. After optimization, a limit of detection of 0.03 ng/mL and a linear range from 0.09 to 16.0 ng/mL were achieved. Recovery was recorded as 83.1%–112.0% along with satisfactory results regarding inner- and inter-assay precision (relative standard deviation, RSD < 6.4%). Little cross-reaction was observed. Additionally, the POCAD was validated by high-performance liquid chromatography (HPLC) by using peanut and corn samples. The portable POCAD exhibits strong potential for applications in the on-site detection of small toxic molecules to ensure food safety.

Highlights

Aflatoxins are mainly synthetized from a polyketide pathway of Aspergillus flavus and Aspergillus parasiticus [1]
B1 (AFB1 ) antigen was coated on the bottom of the microwell before the extracting sample solution and monoclonal antibody against aflatoxins were simultaneously added
The Au@platinum nanoparticles (PtNPs)-IgG was added into the microwell

Summary

Introduction

Aflatoxins are mainly synthetized from a polyketide pathway of Aspergillus flavus and Aspergillus parasiticus [1]. Aflatoxins have been considered as the major food safety threat since their initial detection in the 1960s [2]. The toxicity of aflatoxin is essentially due to: (i) acute aflatoxicosis resulting in hepatic damage, alimentary tract harm, and even death [3]; and (ii) chronic exposure resulting in mutagenic and hepatotoxic effects, immune suppression, and cancer [4]. It was reported that aflatoxins induce 4.6%–28.2% of global hepatocellular carcinoma [5]. The major agricultural products and food matrices are contaminated by aflatoxins from farm to table under favorable environmental conditions, especially in peanut and corn [6]. Serious aflatoxin-induced food safety issues cause billions of dollars to be lost in trading and health care. Monitoring aflatoxin contamination in agro-food is essential, due to a growing demand for on-site aflatoxin monitoring

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