Application of Surface Modified Silica Thin Films to Biosensors

摘要

Previous studies showed that it is possible to obtain a high yield of immobilization of biological compounds onto commercial glass lamellae by increasing the number of silanol groups. This can be achieved through the deposition of a thin film of silica on common glass using r.f.magnetron non reactive sputtering. The aim of this work was to produce thin surfaces with a high concentration of silanol groups for coating the glass core of optical fibers used in some biosensar systems. Depositions were carried out in a reactive environment and the influence of the discharge gases (Ar/H_2 and Ar/H-2O) on the characteristics of films was assessed. The characterization of the coatings was performed by electron probe microanalysis (EPMA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), atomic force microscopy (AFM), contact angle technique and thermogravimetric analysis (TG). The characterization of the silica thin films showed that the use of Ar/H_2O as the discharge gas, with a deposition time of 1 hour, produced a coating suitable for the envisaged applications. Under these conditions, the concentration of silanol was appropriated for the immobilization of the biological compound and the thickness of the film was of 0.12μm.