Plasmonic fiberoptic absorbance biosensor (P-FAB) for evaluation of the antibody stability upon evanescent wave excitation at 280 nm

Intrinsic optical absorption of proteins at 280 nm facilitates the realization of label-free fiberoptic absorbance biosensor (FAB) using U-bent fiber optic probes with high evanescent wave absorbance (EWA) sensitivity. However, the antibodies subjected to EW-based UV excitation may undergo denaturation, leading to an undesirable loss of assay sensitivity. Here, the human immunoglobulin G (HIgG) antibody immobilized U-bent silica fiberoptic probes were subjected to an EW-based UV excitation of 0,1, 3, and 6 hours. Its influence on their antigen-binding activity was determined by means of EWA response (at 530 nm) to a direct immunoassay with plasmonic labeled anti-HIgG.