Electrochemical DNA-biosensors: Two-electrode setup well adapted for miniaturized devices

The proof of concept of a DNA-biosensor based on a two-electrode electrochemical setup and using a microelectrode as working electrode, well adapted for detection in microliter samples and miniaturization, is presented herein. A 23-base DNA-probe self-assembled monolayer was first formed onto a 50 μm-diameter gold surface. The microelectrode extremity was then immersed in a 50 μL DNA-target solution drop itself deposited onto a 2 mm-diameter gold counter electrode. Transduction occurs via long-range electron transfer, which is enhanced subsequently to hybridization, due to DNA-base π-stacking. Single mismatch detection of this first prototype was matched at room temperature in the nanomolar range without any optimization.