Publication date: Oct 03, 2024

A low-cost, lab-made polytetrafluoroethylene micro-cell, equipped with three electrodes, wasd eveloped for the impedimetric detection of SARS-CoV-2. The gold working electrode was modified with a double-ended thiolated poly-adenine probe, which was conjugated with magnetic Fe₃O₄@Au nanoparticles (FeO@Au-(S-polyA-S)-Au). After the loop-mediated isothermal amplification (LAMP) of viral RNA, the single-guide RNA (sgRNA), specifically bound to the SARS-CoV-2 target sequence, activates Cas12a. Cas12a then cleaved the immobilized probe. As a result, the magnetic FeO@Au nanoparticles were released and adsorbed onto the gold electrode surface, using an external magnet. This process increased the physical surface area of the gold electrode, facilitating redox ion ([Fe(CN)]) electron transfer. The decrease in the charge transfer resistance was utilized for SARS-CoV-2 detection. Our LAMP-CRISPR/Cas12a-based impedimetric biosensor, powered by FeO@Au-(S-polyA-S)-Au, demonstrated impressive capabilities, including a remarkable detection limit of 0. 8 aM (0. 48 copies/uL) and a linear range of 0. 01 to 36. 06 fM.

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