posted on 2006-11-29, 00:00authored byEric Green, Mark J. Olah, Tatiana Abramova, Lance R. Williams, Darko Stefanovic, Tilla Worgall, Milan N. Stojanovic
We report a rational approach to the construction of cross-reactive arrays for steroids consisting
of five to seven sensors incorporating modified oligonucleotides. The sensors for our arrays were selected
to maximize their differential responses to the two steroids most different in an arbitrarily chosen parameter
named “shape-length”. The arrays incorporated three previously unreported types of sensors identified
through a massive screening effort: (1) three-way junction sensors with neutralized charges within junction;
(2) “self-aggregating sensors”; and (3) sensors incorporating fluorophore directly in a three-way junction
as a spacer. The arrays were tested on seven steroids and an alkaloid (cocaine) over a range of
concentrations, and achieved 92−96% accuracy in class assignments, despite the close structural similarities
between steroids.