Target-Responsive Regulation of Bacteria-Surface Magnetic Element for Self-Powered Analysis of Aflatoxin B1 in Microbial Fuel Cell

The limitation of the sensing mode greatly restricts the detectable species and detection specificity of microbial fuel cell-based self-powered biosensors (MFC-SPBs). Herein, we develop a bacterial quantity change-based sensing mode for MFC-SPBs, in which the Fe3O4@Au content modified on exoelectrogenic bacteria is designed to correlate with analyte concentration for regulating the bacterial numbers absorbed onto the magnetic auxiliary anode. The polydopamine and Au nanoparticles comodified bacteria are attached with complementary DNA for hybridization with aptamer-modified Fe3O4@Au nanospheres. When aflatoxin B1 (AFB1) is used as the model analyte, its appearance can cause the liberation of Fe3O4@Au nanospheres from bacteria due to aptamer recognition. Furthermore, introduced exonuclease I can achieve a recycling amplification effect, intensifying the release of Fe3O4@Au nanospheres. With the decrease in bacteria-surface Fe3O4 content, bacteria that can be adsorbed onto the anode in a magnetic field will be reduced, leading to a decrease in the performance of MFC-SPBs. The results show that the developed MFC-SPBs can quantitatively determine AFB1 with a limit of detection of 5 nM (S/N = 3). Also, the MFC-SPBs show good detection specificity and can assess AFB1 in peanut samples. Considering the good specificity and species diversity of aptamers, we believe that this developed sensing mode will receive wide attention in the field of MFC-SPBs.