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Fluorescence Blinking as an Output Signal for Biosensing

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journal contribution
posted on 31.10.2016, 00:00 by Brandon Roark, Jenna A. Tan, Anna Ivanina, Morgan Chandler, Jose Castaneda, Ho Shin Kim, Shriram Jawahar, Mathias Viard, Strahinja Talic, Kristin L. Wustholz, Yaroslava G. Yingling, Marcus Jones, Kirill A. Afonin
We demonstrate the first biosensing strategy that relies on quantum dot (QD) fluorescence blinking to report the presence of a target molecule. Unlike other biosensors that utilize QDs, our method does not require the analyte to induce any fluorescence intensity or color changes, making it readily applicable to a wide range of target species. Instead, our approach relies on the understanding that blinking, a single particle phenomenon, is obscured when several QDs lie within the detection volume of a confocal microscope. If QDs are engineered to aggregate when they encounter a particular target molecule, the observation of quasi-continuous emission should indicate its presence. As proof of concept, we programmed DNAs to drive rapid isothermal assembly of QDs in the presence of a target strand (oncogene K-ras). The assemblies, confirmed by various gel techniques, contained multiple QDs and were readily distinguished from free QDs by the absence of blinking.