Fibre-optic genosensor for specific determination of femtomolar DNA oligomers

The binding of DNA oligonucleotides to immobilized DNA-targets using a fibre optic fluorescence sensor is demonstrated. 13mer oligonucleotides were attached to the core of a multimode fibre. The complementary sequence was detected by use of a fluorescent double strand specific DNA ligand (YOYO and PicoGreen). The evanescent field was employed to distinguish between bound and not bound species. The template DNA-oligomer was immobilized either by direct coupling to the activated sensor surface or using the avidin-biotin bridge. Single base mismatches in the target sequence were detected; and a detection limit of the sensor of 30 fM (3.2 attomoles) was found for the matching target.