Photocatalytic Organic Semiconductor-Bacteria Imprinted Polymers for Highly Selective Determination of Staphylococcus aureus at the Single-Cell Level

This work utilized a combination of photocatalytic organic semiconductors and bacteria to create a photocatalytic organic semiconductor-bacterial biomixture system based on a bacteria imprinted polymers (OBBIPs-PEC) sensor, for the detection of S. aureus with high sensitivity in "turn-on" mode at the single-cell level. This outstanding sensor arises from an integration of two different types of semiconductor materials to form heterojunctions. As well this sensor involves combining a semiconductor material with cationic side chains and an electron transport chain within a natural cellular environment, in which the cationic side chain of poly(fluorene-co-phenylene) organic semiconductor at 2-(4-mesyl-2-nitrobenzoyl)-1,3-cyclohexanedione (PFP-OC@MNC) demonstrated the ability to penetrate the cell membrane of S. aureus and interact with specific binding sites through electrostatic interactions. As the cavities in the BIPs were occupied by S. aureus, during light irradiation, the electrons stimulated by the photoexcitation process in the manufactured PFP-OC@MNC semiconductors were successfully transmitted to S. aureus, where these electrons played a role in the regeneration of NADH and FADH₂, and then the presence of S. aureus acted as a proficient electron acceptor for photoexcited electrons; thereby the PEC response of the OBBIPs-PEC sensor was significantly enhanced. Of note, it exhibited high selectivity for S. aureus over other bacteria and maintained excellent performance in complex matrices, distinguishing S. aureus with concentrations as low as 10 CFU/mL. This work dramatically reduces the influence of interference factors in the traditional mode and offers a powerful way for microorganism detection in food and environmental fields.