DNA biosensors for E. Coli O157:H7 detection in drinking water resources using sol-gel derived waveguides

Abstract

SiO<inf>2</inf> -TiO<inf>2</inf> thin films were fabricated by sol-gel dip coating technique to be used as the fiber optic guiding layers of optical DNA biosensors. The chemical structure of the films was examined by Fourier Transformed Infrared Spectroscopy (FTIR, Bio - Rad Tropical Option for FTS 175 C) and the surface morphology of the films was observed by Scanning Electron Microscopy (SEM, Philips XL 30 SFEG). The probe DNA was immobilized on the surface and the pores of the waveguide films before the hybridization process was carried out. By using Metricon 2010 prism coupler, 12 different spots were determined to be measured. Then the mean refractive index values and their standard deviations were calculated. The increased refractive index values after the DNA immobilization indicated that immobilization was successfully achieved. Further increase after the hybridization with complementary DNA showed the possibility of detection of the E. coli O157:H7 EDL933 species by using 20-mers (5'- TAATATCGGTTGCGGAGGTG-3') sequence of GeneID: 957271. © 2009 Springer Berlin Heidelberg. © 2010 Elsevier B.V., All rights reserved.