High-sensitivity colorimetric detection of DNA hybridization on a gold surface with high spatial resolution

We present a colorimetric detection method which is able to detect biotinylated oligonucleotides hybridized to thiolated complementary strands bound to a gold surface. Unlike previous colorimetric detection methods, this technique has the advantage of providing spatial information which is of higher resolution than that of an optical microscope, and can also be used on a gold surface. Bulk concentrations down to 10(-9) M of biotinylated oligonucleotides were detectable representing fewer than 7000 molecules of hybridized DNA on a microarray-sized spot (empty set approximate to 35 mum). This technique has potential for DNA detection in molecular electronics and molecular assembly applications, where a high-resolution detection on metal surfaces is required.