The present work describes an all-fiber hybridization assay sensor that relies on the evanescent field excitation of fluorescence from surface-bound fluorophores. The evanescent field is made accessible through the use of a long adiabatically tapered single-mode fiber probe. A semiconductor laser operating at 785 nm wavelength is used in a pulsed mode to excite fluorescence in the tapered region of a fiber probe using the near-infrared fluorophore IRD 41. We have carried out real-time hybridization tests for IRD 41-labeled oligonucleotide at various probe concentrations binding to complementary oligonucleotide cross-linked to the tapered fiber surface. Short oligonucleotides (20-mer) bound to the fiber surface have been used to detect near-infrared dye labeled complementary sequences at sub-nanomolar levels. Sandwich assays with total RNA were conducted to examine the capability of the biosensor for detecting bacterial cells using rRNA as the target. The results indicate that this fluorosensor is capable of detecting H. pylori in a sandwich assay at picomolar concentrations.

Date Published: 28 April 1999
PDF: 4 pages
Proc. SPIE 3666, International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '98, (28 April 1999); doi: 10.1117/12.347981

Published in SPIE Proceedings Vol. 3666:
International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '98
Anurag Sharma; Banshi Dhar Gupta; Ajoy K. Ghatak, Editor(s)