Plastic Optical Fiber Immunosensor for Escherichia Coli Detection

Conventional methods for pathogen detection mainly rely on time-consuming enrichment steps followed by biochemical identification strategies, which require assay times ranging from 24 hours to up to a week. However, in recent years, significant efforts have been made towards the development of biosensing technologies enabling rapid and close-to-realtime detection of waterborne pathogens. In previous studies, we developed a plastic optical fiber (POF) immunosensor using an optoelectronic configuration consisting of an U-shape probe connected to an LED and a photodetector. Bacterial detection was evaluated with the immunosensor immersed in a bacterial suspension in water with a known concentration. In the present work, we tested the sensitivity of a new optoelectronic configuration consisting of two POF U-Shape probes, one as the reference and the other as the immunosensor, for the detection of Escherichia coli (E. coli). In addition, another way of detection was tested where the sensors were calibrated on the air, before immersed in bacterial suspension and then read on the air again, making the immunosensor more sensitive and with a faster detection time. The developed sensor was capable to detect the presence of E. coli in a concentration of 10
⁴
CFU/mL (CFU - (Colony Forming Unity) in less than 10 minutes, a shorter time than in any previous studies applying fiber-optic-based biosensors, and much with a simpler and quicker methodology when compared with conventional laboratory technology.