A Reusable Dual-Mode Aptasensor Based on Bipolar Electrode for Sensitive Detection of Live Clostridium perfringens

Clostridium perfringens is an important foodborne pathogen, and due to the lack of aptamers, its detection has been dependent on DNA extraction. It is not only time-consuming and costly but also unable to distinguish between live and dead bacteria. Herein, a high affinity and specificity aptamer (K_d = 66.91 ± 22.02 nM) targeting C. perfringens was first reported, which was screened by the whole-bacteria SELEX. Building on this, we developed a reusable dual-mode aptasensor based on a bipolar electrode (BPE) system. The cathode end was used to modulate the current through the extracellular electron transfer (EET) mechanism of living bacteria, and CeO₂@polyaniline (CeO₂@PANI) nanocomposite was utilized to collect voltage at the anode. In addition, connecting an LED in series with the BPE not only provided a G-value signal but also allowed the BPE to be reused (12 times). Ultimately, the synergistic effect of the cathode and anode resulted in detection limits of 2.50 CFU/mL (voltage) and 2.58 CFU/mL (G-value) for the aptasensor. Benefiting from the physical action of BPE, the matrix effect was less than 7% in both chicken breast and milk. Furthermore, the aptasensor achieved consistent results with the qPCR assay in the testing of 48 actual samples. And the combination of the aptamer and BPE reduced the detection time to 3 min. This method not only provides a new direction for BPE to be reusable but more importantly provides new ideas for the identification of live and dead bacteria.