Fabrication of magnetically assembled aptasensing device for label-free determination of aflatoxin B1 based on EIS

Aflatoxin B1 (AFB1), one of the most common mycotoxins in food matrixes, has been identified as the most toxic contaminant with mutagenic, teratogenic, immunosuppressive, and carcinogenic effects. In this work, a magnetically assembled aptasensing device has been designed for label-free determination of AFB1 by employing a disposable screen-printed carbon electrode (SPCE) covered with a designed polydimethylsiloxane (PDMS) film as the micro electrolytic cell. The magnetically controlled bio-probes were firstly prepared by immobilization of the thiolated aptamers on the Fe₃O₄@Au magnetic beads, which was rapidly assembled on the working electrode of SPCE within 10 s, by using a magnet placed at the opposite side. The PDMS film with a centered hole was covered on the SPCE surface to achieve a more practicable and flexible electrochemical measurement. In this effort, a label-free aptasensor for the sensitive and selective determination of AFB1 has been developed using electrochemical impedance spectroscopy upon the biorecognition between aptamers and the targets. The developed method had a wide linear range of 20 pg mL^-1-50 ng mL^-1 with a detection limit of 15 pg mL^-1 (S/N = 3) and succeeded in spiked samples of peanuts. The developed aptasensing device shows fantastic application prospect with simple design, easy operation, low cost, and high sensitivity and selectivity characteristics. This sensing strategy represents a promising path toward routine quality control of food safety and creates the opportunity to develop facile aptasensing device for other targets.