Signal Amplification Strategy-Assisted Dual Photoelectrode Fuel Cell Self-Powered Sensor for MecA Gene Detection

The mecA gene can make bacteria resistant to drugs, and its constant diffusion seriously threatens ecological safety of water and public health, which calls for the development of sensitive detection strategies. However, its low concentration in water and interference from complex environments make it still challenging to achieve sensitive detection. Herein, a photocatalytic fuel cell (PFC)-based self-powered electrochemical sensor was constructed for mecA gene detection through integrating the dual photoelectrode structure with a magnetic nanobead (MB)-assisted 3D DNA walker signal amplification strategy. To enhance the photoelectric conversion efficiency, the Bi₂S₃/Ti₃C₂T_x@Au heterojunction was constructed, which greatly improved the photocurrent. Besides, the introduction of the CuFeO₂ photocathode further enhanced light absorption and increased the output signal up to 555 mV, which was about 1.4 times that of the single electrode system. In addition, the MB-assisted 3D DNA walker strategy isolated the target and converted it into output DNA, which increased the fixation of SiO₂ on the electrode and led to a decline of output signals. The constructed PFC-SPES had the ability to detect the target within the range of 10 fM to 10 nM with a detection limit as low as 1.14 fM, presenting a high sensitivity and universal detection choice for quick and accurate analysis of pollutants in water samples.