Fabrication of A Quinone Containing Layer on Gold Nanoparticles Directed To A Label-Free and Reagentless Electrochemical miRNAs Sensor
In this work, we report a simple electrochemical method to fabricate of label-free and reagentless electrochemical sensor for microRNAs detection based on self-assembly of a multifunctional layer on gold nanoparticles-modified glassy carbon electrodes (AuNPs/GCE). The self-assembled monolayer (SAM) is made of a mixture of 5-hydroxy-3-hexanedithiol-1,4-naphthoquinone (JUG-SH) which plays the role of transducing element, and of 6-mercaptohexanoic acid (6-MHA). The carboxylic group of 6-MHA is used as anchoring site for grafting of a DNA-NH2 probe and the quinone group as an immobilized redox group for probing biomolecular interactions. Hybridization with perfect base pairing at the SAM/solution interface generates a current increase named “signal-on” that can be recorded simply by square wave voltammetry (SWV) in a phosphate buffer at very low potentials (between 0 and -1 V vs. SCE). The sensor is selective and highly sensitive, with a detection limit of ca. 100 fM.