Fluorescence IgG immunosensor based on a micro flow cell containing controlled pore glass as immobilisation support

Biosensor miniaturisation often requires the construction of micro volume c ells using micro-machining techniques. In this work, a micro flow cell made of a transparent polymer [poly(methyl methacrylate)] developed for using w ith a fluorescence immunoglobulin G (IgG) immunosensor is described. The mi cro flow cell provides space to enclose a small amount of controlled pore g lass (CPG), a transparent support that can host and covalently bind the bio molecules. The immobilisation of IgG on CPG permits the development of an o ptical immunosensor for the detection of fluorescein isothiocyanate (FITC)- labelled anti-IgG. In this immunosensor the excitation light is provided by an argon ion laser and guided by an optical fibre to the flow cell, where the fluorescence signal is filtered by a long-pass barrier filter (OG515) a nd then detected by a close positioned photodiode. This signal was found to be proportional to the amount of anti-IgG-FITC bound to the immobilised Ig G during a direct immunochemical reaction. Characterisation of the CPG as a n optical medium and immobilisation support was performed. CPG produces int ense light scattering and good permeability to fluids, and also a typical i mmobilisation rate for IgG of about 90% of the initial amount of antibody. The described immunosensor shows a detection limit for anti-IgG-FITC of 6.3 nM and a sensitivity of 9.5 mu V nM(-1). This immunoptode developed with a micro flow cell has been shown to be a suitable system for the detection o f immunoglobulins.