Enhanced Electron Transfer Mediated by Conjugated Polyelectrolyte and Its Application to Washing-Free DNA Detection

Ji-Eun Jeong (박사과정)

Direct electron transfer between a redox label and an electrode requires a very short working distance (<1-2 nm), and in general an affinity biosensor based on the direct electron transfer requires a finely smoothed Au electrode surface to support efficient target binding. Here, we report that direct electron transfer over a longer working distance is possible between (i) an anionic p-conjugated polyelectrolyte (CPE) label having many redox-active sites and (ii) a readily prepared, thin polymeric monolayer-modified indium-tin oxide (ITO) electrode. In addition, the long and flexible CPE label (~18 nm for 10 kDa) can approach the electrode within the working distance after sandwich-type target-specific binding, and fast CPE-mediated oxidation of ammonia-borane along the entire CPE backbone affords high signal amplification. Negatively charged casein and hydrophilic side chains of the CPE minimize nonspecific adsorption of a CPE-labeled DNA onto the ITO electrode. All are beneficial for sensitive washing-free DNA detection.

https://pubs.acs.org/doi/abs/10.1021/jacs.7b12382