Biofunctionalization of chalcogenide glass fiber to enhance real time and label free detection by mid infrared spectroscopy.

Bio-functionalized chalcogenide infrared optical glass fibers have been designed for evanescent wave mid-infrared spectroscopy. Surface biotinylation of the fiber tapered sensing zone has been achieved by reactivity of a maleimide function on sulfhydryl moieties of the glassy surface. Biotin-streptavidin interactions were studied by fiber evanescent wave spectroscopy. Kinetic measurement comparisons of functionalized and non-functionalized fiber surfaces for various protein concentrations have demonstrated the efficient bio-selectivity of the functionalized glass fibers. The protein enrichment of the functionalized glassy surface allows for a significant increase of the protein detection limit, greater than two orders of magnitude as compared to reference non-functionalized fibers. A detection of minute quantities at concentrations as low as 10 parts-per-billion is demonstrated. This study shows that bio-functionalized chalcogenide optical fibers allow to combine successfully surface bio-selectivity and infrared absorption fingerprints measurements to get a remarkable sensitivity enhancement of fiber evanescent wave detection methods in the mid infrared spectral range.