A model of optical immunosensor for hemoproteins based on Langmuir-Blodgett films of FITC-labelled immunoglobulin G

A direct optical method based on the interaction of hemoproteins with a thi n film modified with a fluorescent label specific immunoglobulin C (IgG) ha s been developed fur the fluorimetric determination of antigen-antibody bin ding. The sensing surface is composed of a Langmuir-Blodgett (LB) film of f luorescein isothiocyanate (FITC)-modified IgG. The LB film binds heme-conta ining antigen and changes its fluorescent properties owing to resonant ener gy transfer in the donor-acceptor pair FITC-heme. The quenching of FITC flu orescence emission grows under increasing concentrations of hemoproteins ov er a broad range; the quenching degree depends on the molecular weight of t he hemoprotein. The main advantage of the proposed method is the possibilit y of developing a direct immunosensor based un evanescent excited fibre opt ics. (C) 2000 Elsevier Science S.A. All rights reserved.