Bacteriophage Adhesin-Coated Long-Period Grating-Based Sensor: Bacteria Detection Specificity

In this paper, we study a label-free detection specificity of an optical fiber long-period grating (LPG) biosensor working near the dispersion turning point of higher order cladding modes. The LPG sensor is functionalized with bacteriophage adhesin and tested with specific and nonspecific bacteria dry weights. It is shown that that such a biosensor is able to selectively bind to specific bacterial strains. In the experiments bacteria dry weights of E. coli B were used as a positive test and E. coli K12 and Salmonella enterica as negative tests. The resonance wavelength shift induced by E. coli B reaches over 90 nm, while for E. coli K12 and Salmonella enterica approximately 40 and 20 nm, respectively. Additionally, whole-cell-ELISA tests were made to confirm LPG-based biosensor outcomes, and numerical simulations were conducted to estimate biolayer impact on sensor's performance.