Antibody-Functionalized Plasmonic Biofiber Sensors with Layered Nanomaterials for Sensitive <i>Listeria monocytogenes</i> Detection

Listeria monocytogenes (L. monocytogenes) is one of the pathogenic bacteria threatening human health. Upon infection, it causes symptoms such as sepsis and meningitis in immunocompromised individuals. This work introduces a biofiber sensor that utilizes the plasmonic principle for detecting L. monocytogenes. The fiber structure consists of multimode fiber (MMF) and seven-core fiber (SCF). The core-mismatch configuration between MMF and SCF, along with the W-shaped architecture of the seven-core fiber, amplifies the evanescent field on the fiber surface. Gold nanoparticles are affixed to the sensor region’s surface to elicit the plasmonic effect. Additionally, the layered structure of bismuthene and antimonene functionalizes the fiber, improving the biocompatibility and durability of the fiber sensing region. Moreover, the layered nanostructured bismuthene and antimonene provide a high specific surface area, offering additional reference sites for antibody functionalization. To enhance the specificity of the sensor, an anti-Listeria monocytogenes functional fiber is used. The results show that the sensitivity of the sensor is 0.45 nm/log10(CFU/mL), and the detection limit is 0.89 CFU/mL when the concentration of L. monocytogenes is between 100 and 108 CFU/mL. In addition, the actual test performance of the sensor is evaluated by using real samples. The recovery rates of milk, cheese, tomato, and ice-cream range from 133–91.5, 133–67, 133–67, and 100–74.9%, demonstrating its effectiveness in detecting L. monocytogenes.