Novel 3S-shaped biophotonic sensor utilizing MoS2–NSs/ZnO–NWs/AuCu–NCs for rapid detection of <i>Shigella flexneri</i> bacteria

This paper describes a unique, extremely sensitive biophotonic sensor with a three-tier S-tapered (3S) structure. It is designed for the real-time detection of Shigella flexneri (S. flexneri), a common foodborne pathogen that causes severe gastrointestinal diseases. The sensor development includes three distinct diameters of S-tapered structures. The performance of tapered sections was improved by using molybdenum disulfide nanosheets (MoS2-NSs), zinc oxide nanowires (ZnO-NWs), and photoluminescent bimetallic gold–copper nanoclusters (AuCu–NCs). These nanoparticles greatly improve the sensor’s performance. The sensor is further functionalized using anti-S. flexneri antibodies, allowing for the precise detection and capture of the target bacterium. The results show that the sensor can detect S. flexneri rapidly and accurately, with a linear detection range of 1–108 colony-forming units per milliliter (CFU/ml) and a low detection limit of 4.412 CFU/ml. In addition, the sensor’s ability to identify S. flexneri biofilms is demonstrated. Biofilm detection allows us to better understand and control biofilm concerns in the environment, equipment, and biomedical devices. Aptamer examines confirm the sensor’s ability to detect S. flexneri from the lateral direction. This study makes a significant contribution to the field of biosensing because no biophotonic sensor has previously been developed specifically for the detection of S. flexneri, fulfilling a critical gap in the arena of food safety and pathogen detection. The 3S sensor’s performance, robustness, and potential for practical applications make it an important addition to the field of photonics.