Characterization of DNA hybridization on the optical fiber surface

Immobilized oligonucleotide has been utilized widely for the development of DNA biosensors. In this study we report the characterization of the oligonucleotide probe hybridization process on the optical fiber surface. Streptavidin was covalently linked to the core surface of a multimode optical fiber and used as a bridge for the immobilization of a thin layer of 5′-biotinylated oligonucleotide probes. Following hybridization to the 5′-fluorescein labeled target oligonucleotides in solution, the fluorescence signal generated on the optical fiber surface by laser excitation traveled back into the optical fiber core and was collected at the proximal end. With the evanescent wave excitation and detection method used, a very sharp discrimination of bulk fluorescence against surface excitation in combination with high excitation intensities could be achieved. The preliminary results showed that the hybridization process on the optical fiber surface was specific and it could identify a single base mismatch in the hybridized duplex under experimental conditions. Hybridization performance of surface immobilized oligonucleotides to various concentrations of target oligonucleotides in solution was studied. Regeneration of the optical fiber surface was possible without a significant loss of the hybridization ability.