An ultrasensitive electrochemical biosensor for simultaneously detect microRNA-21 and microRNA-155 based on specific interaction of antimonide quantum dot with RNA

•We developed a novel electrochemical microRNA biosensor based on AMQD/SWCNTs for detection of microRNA-155 and microRNA-21.•The strong adsorption of AMQD to ssRNA and their low affinity for dsRNA results in a change in the oxidation peak of the dye.•The detection limits of microRNA-21 and microRNA-155 for breast cancer related markers were as low as 64 aM and 89 aM.