American Chemical Society
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Tuning Toehold Length and Temperature to Achieve Rapid, Colorimetric Detection of DNA from the Disassembly of DNA–Gold Nanoparticle Aggregates

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journal contribution
posted on 2016-02-09, 12:38 authored by Michael K. Lam, Tendai Gadzikwa, Trang Nguyen, Abu Kausar, B. Safeenaz Alladin-Mustan, Md. Delwar Sikder, Julianne M. Gibbs-Davis
Gold nanoparticles have been widely utilized to achieve colorimetric detection for various diagnostic applications. One of the most frequently used methods for DNA detection involves the aggregation of DNA-modified gold nanoparticles driven by target DNA hybridization. This process, however, is intrinsically slow, limiting its use in rapid diagnostics. Here we take advantage of the reverse process: the disassembly of preformed aggregates triggered by the addition of target DNA via a strand displacement mechanism. A systematic study of the dependence of the disassembly rate on temperature, with and without toeholds, has delivered a system that produces an extremely rapid colorimetric response. Furthermore, using an optimal toehold length of 5 nucleotides, target triggered disassembly is rapid over a wide range of ambient temperatures. Using this overhang system, simple visualization of low picomole amounts of target DNA is possible within 10 min at room temperature.