Low-Cost and Highly Sensitive Immunosensing Platform for Aflatoxins Using One-Step Competitive Displacement Reaction Mode and Portable Glucometer-Based Detection

Abstract

Aflatoxins are highly toxic secondary metabolites produced by a number of different fungi and present in a wide range of food and feed commodities. Herein, we designed a simple and low-cost immunosensing platform for highly sensitive detection of mycotoxins (aflatoxin B1, AFB1, used as a model) on polyethylenimine (PEI)-coated mesoporous silica nanocontainers (PEI-MSN). The assay was carried out by using a portable personal glucometer (PGM) as the readout based on a competitive displacement reaction mode between target AFB1 and its pseudo-hapten (PEI-MSN) for monoclonal anti-AFB1 antibody (mAb). To construct such an assay protocol, two nanostructures including mAb-labeled gold nanoparticle (mAb-AuNP) and PEI-MSN were initially synthesized, and then numerous glucose molecules were gated into the pores based on the interaction between negatively charged mAb-AuNP and positively charged PEI-MSN. In the presence of target AFB1, a competitive-type displacement reaction was implemented between mAb-AuNP and PEI-MSN by target AFB1 through the specific antigen-antibody reaction. Accompanying the reaction, target AFB1 could displace the mAb-AuNP from the surface of PEI-MSN, resulting in the release of the loading glucose from the pores due to the gate opened. The released glucose molecules could be quantitatively determined by using a portable PGM. Under optimal conditions, the PGM signal increased with the increment of AFB1 concentration in the range from 0.01 to 15 μg/kg (ppb) with a detection limit (LOD) of 5 ng/kg (5 ppt) at the 3sblank criterion. The selectivity and precision were acceptable. Importantly, the methodology was further validated for assaying naturally contaminated or spiked blank peanut samples, and consistent results between the PGM-based immunoassay and the referenced enzyme-linked immunosorbent assay (ELISA) were obtained. Therefore, the developed immunoassay provides a promising approach for rapid screening of organic pollutants because it is simple, low-cost, sensitive, specific, and without the need of multiple separation and washing steps.

Transforming the blood glucose meter into a general healthcare meter for in vitro diagnostics in mobile health

“…Instead of using enzymes to generate glucose, an alternative strategy to provide the necessary link between target recognition and glucose levels is to directly release encapsulated glucose from nanocontainers, such as mesoporous silica (Fu et al, 2013, Gao et al, 2014, Hou et al, 2014, Tang et al, 2014, Wang et al, 2014b) and liposome (Zhao et al, 2015b), in response to a target recognition event. Gao and co-workers (Gao et al, 2014) reported the use of magnetic mesoporous particles as glucose nanocontainers, gated by antibody-mediated target responsive poly(ethyleneimine)-coated polystyrene microsphere (PEI-PSMS).…”

Enzymatic Hydrolysate-Induced Displacement Reaction with Multifunctional Silica Beads Doped with Horseradish Peroxidase–Thionine Conjugate for Ultrasensitive Electrochemical Immunoassay

“…AFB 1 -spiked peanut standards with various concentrations were prepared via our previously reported method. 52 Briefly, 5.0 g of the blank peanut sample milled by using a Midea food mixer (BP252AG, Guangdong, China) was initially extracted with 37.5 mL of MeOH/water (80:20, v/v) after being stirred for 60 min at room temperature (RT) followed by filtration. Then the extract (20 mL) was diluted into 60 mL of ultrapure water to acquire a final concentration of 20% (v/v) MeOH.…”

Electrochemical assay of α-glucosidase activity and the inhibitor screening in cell medium

“…However, electrochemical method has not been established to determine α-glucosidase activity and screen its inhibitor. On the other hand, one-step competitive displacement reaction strategy attracted substantial research interests recently in the analytical fields, because of its simplicity, specificity and reliable quantitative results (Ma et al, 2013;Salamon et al, 2015), although most of the present displacement reaction systems are applied to the detection of nucleic acids and the antigen-antibody reaction (Sapsford et al, 2002;Tang et al, 2014). It happens that the strategy was reported to be devoted to the investigation of the interaction between sugar and boronic acid , thus reversible covalent bonds between phenylboronic acid and 1,2-/1,3-cis-diols in aqueous solution have been used for the construction of molecular receptors (Yum et al, 2012).…”