A fiber-optic microarray biosensor using aptamers as receptors

A fiber-optic biosensor using an aptamer receptor has been developed for th e measurement of thrombin, An antithrombin DNA aptamer was immobilized on t he surface of silica microspheres, and these aptamer beads were distributed in microwells on the distal tip of an imaging fiber. A different oligonucl eotide bead type prepared using the same method as the aptamer beads was al so included in the microwells to measure the degree of nonspecific binding. The imaging fiber was coupled to a modified epifluorescence microscope sys tem, and the distal end of the fiber was incubated with a fluorescein-label ed thrombin (F-thrombin) solution. Nonlabeled thrombin could be detected us ing a competitive binding assay with F-thrombin, The aptamer beads selectiv ely bound to the target and could be reused without any sensitivity change. The fiber-optic microarray system has a detection limit of 1 nM for nonlab eled thrombin, and each test can be performed in ca, 15 min including the r egeneration time. (C) 2000 Academic Press.