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 thin film modified with a fluorescent label specific immunoglobulin G (IgG) has been developed for the fluorimetric determination of antigen–antibody binding. The sensing surface is composed of a Langmuir–Blodgett (LB) film of fluorescein isothiocyanate (FITC)-modified IgG. The LB film binds heme-containing antigen and changes its fluorescent properties owing to resonant energy transfer in the donor–acceptor pair FITC–heme. The quenching of FITC fluorescence emission grows under increasing concentrations of hemoproteins over a broad range; the quenching degree depends on the molecular weight of the hemoprotein. The main advantage of the proposed method is the possibility of developing a direct immunosensor based on evanescent excited fibre optics.