Regenerable ratiometric aptasensor based on electro-oxidation conducted host-guest dissociation for aflatoxin B1 detection in grains

Abstract

Aflatoxin B1 (AFB1) leads to considerable pollution to grains and causes harmful effects on human health. Herein, we present a regenerable AFB1 aptasensor, based on electro-oxidation conducted host-guest dissociation for natural AFB1 detection. Molybdenum disulfide-Au nanobipyramids (MoS2-AuNBPs) serve as signal carriers and are equipped with indicative thionine (Thi) and semi-complementary chains to AFB1 aptamer (ssDNA). The electrode surface is modified with gold nanoparticles (AuNPs) and β-cyclodextrin (β-CD). Aptamer-ferrocene (Apt-Fc) can be recognized in cavity of β-CD through host-guest interaction. The signal probe, self-assembled with AFB1 Apt via hybridization, can be easily expelled by AFB1, bringing a ratiometric readout ΔIThi/IFc. Particularly, regeneration process is realized with synergy of AFB1-conducted Apt-ssDNA dissociation and electro-oxidation conducted host (β-CD)-guest (Fc) dissociation. Modifications and regeneration behaviors are morphologically and electrochemically validated. Regenerations are dependably performed in repetitive cycles (N = 7), which exhibit considerable performance in analyses. Electro-oxidation time is experimentally optimized (6 min). This method exhibits wide range from 1.0 pg/mL to 80.0 ng/mL, and limit of detection is 5.0 × 10−1 pg/mL, to target AFB1. During natural AFB1 determinations, proposed readouts are validated with certified HPLC and recovery test. Relative errors and recovery rates are calculated as 2.04–7.22% and 94.41–106.54%, respectively.