SURFACE-ANALYSIS AND CHARACTERIZATION OF CHEMICALLY-MODIFIED CHALCOGENIDE FIBERS

In this paper, the use of several analytical methods for the determina tion of the fiber surface coverage after each step of chemical immobil ization of an enzyme is reported. The enzyme glucose oxidase was immob ilized on the surface of an infrared transparent chalcogenide fiber us ing (3-amino-propyl)triethoxysilane and glutaraldehyde or (gamma-glyci doxypropyl)triethoxysilane as a carrier as described in our previous p apers. This reactive enzyme layer coating the core of the fiber serves to catalyze chemical reactions specifically. However, efficient chemi cal modification for the development of chemical sensors requires that the coating covering the fiber remains homogeneous and stable along t he surface. In order to investigate the surface and to control the qua lity (homogeneity and thickness) of such thin organic layers, it is ne cessary to exploit several surface analysis techniques. Secondary ion mass spectrometry was applied to prove the presence of oxygen and OH g roups on the fiber's surface. Infrared spectroscopy and infrared micro scopy were used to monitor the spectral changes to evaluate informatio n about coatings on a molecular basis whereas the scanning electron mi croscope coupled to an energy-dispersive spectrometer was applied to e valuate information on an elemental basis. Finally, atomic force miscr oscopy was used to examine the morphology of the modified fiber surfac e. In conclusion, the combined evaluation has shown that an enhancemen t of the surface density of the active layer at the IR-transparent fib ers is necessary to exploit the compound-specific potential of the new sensor.