Universal DNA biosensing based on instantaneously electrostatic attraction between hexaammineruthenium (III) and DNA molecules.

Despite rapid progress in DNA biosensors by employing various materials as well as techniques, most of the reported sensors are based on specific recognition of a DNA fragment, however can not perform universal measurement of DNA molecules (i.e. genomic DNA). In this work, we proposed a novel DNA biosensing method based on instantaneously electrostatic attraction (IEA) between hexaammineruthenium (III) and DNA molecules. The current variation of freely diffused Ru(NH3)63+ caused by its quick and strong static interaction with phosphate backbones was employed as a universal probe to detect DNA molecules in solution, with no need for immobilization of capture probes on the electrode. After optimization, 30 μL of 300 μM Ru(NH3)63+ solution was added onto the gold electrode with a working electrode diameter of 2 mm, and a detection limit of 3.8 ng/μL was achieved, which is equivalent to NanoDrop™ One spectrometer, the commonly used instrument for DNA quantification. Using reusable and inexpensive gold electrode, the approach provided an easy-operated sequence-independent DNA detection method, and was proved to be able to detect genomic and plasmid DNA directly.