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-μm-diameter microspheres on the distal face of a 500-μm 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 (∼600 DNA molecules).