High-density fiber-optic genosensor microsphere array capable of zeptomole detection limits.

The detection limit of a fiber-optic microsensor array was investigated for simultaneous detection of multiple DNA sequences. A random array composed of oligonucleotide-functionalized 3.1-microm-diameter microspheres on the distal face of a 500-microm etched imaging fiber was monitored for binding to fluorescently labeled complementary DNA sequences. Inherent sensor redundancy in the microarray allows the use of multiple microspheres to increase the signal-to-noise ratio, further enhancing the detection capabilities. Specific hybridization was observed for each of three sequences in an array yielding a detection limit of 10(-21) mol (approximately 600 DNA molecules).