Dual-Functional Ratio Photoelectrochemical Biosensing Platform for Photothermal Simultaneous Sterilization and Lipopolysaccharides-Mediated Detection of <i>Escherichia coli</i> O157:H7

As biosafety requirements continue to increase, there is a growing interest in foodborne-pathogen detection methods that can be operated safely. In this work, a dual-functional “sterilization-detection” photoelectrochemical (PEC) biosensing platform is developed based on a Fe 3 O 4 /copper-benzene-1,3,5-tricarboxylic acid (Cu-BTC), which integrates efficient photothermal sterilization with excellent photoelectric performance. The aptamer-modified magnetic substrate is employed to specifically capture and magnetically separate Escherichia coli O157:H7, inducing a steric hindrance effect that decreases the photocurrent. Upon near-infrared irradiation, the composite exhibits a strong photothermal response, enabling efficient in situ sterilization of the captured bacteria. Subsequently, the lipopolysaccharides (LPS) released during bacterial lysis are adsorbed onto the Fe 3 O 4 /Cu-BTC surface via Cu–O–P bonds. The phosphate groups in LPS coordinate with Cu 2+, passivating surface defects and suppressing nonradiative recombination, thereby prolonging carrier lifetime and boosting the photocurrent. The resulting ratiometric PEC sensing platform shows a linear range of 2.2 × 10 2 –2.2 × 10 6 CFU/mL with detection limit as low as 41 CFU/mL. Thus, this work not only achieves the enhancement of PEC signals through in situ adsorption of LPS but also proposes an integrated strategy for the simultaneous inactivation and accurate quantification of foodborne pathogens. It demonstrates promising potential for on-site food safety monitoring and proactive biosafety control.