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

MicroRNA exhibits different levels of expression in cancer and can affect the transformation, metastasis, and carcinogenesis of the cancer cell. Herein, we developed a novel kind of electrochemical microRNA biosensor based on antimonide quantum dot (AMQD), aromatic heterocyclic dyes, and single-walled carbon nanotubes (SWCNTs) for specific detection of breast cancer-relevant biomarkers-microRNA-155 and microRNA-21 at the clinic. Compared to graphene, the first principle energetic calculation shows that the antimonide has completely a stronger force interaction with single strand RNA (ssRNA), that is because the antimonide has a more delocalized 5 s/5p orbital. After the addition of complementary microRNAs, due to the low adsorption affinity of double-stranded RNA (dsRNA) to antimonide, the hybridized target is easy to desorb from the antimonide interface, and the oxidation peaks of aromatic heterocyclic dyes are significantly reduced. Results showed the microRNA-21 and microRNA-155 concentrations can be detected from 0 to 1 pM, the detection of time is only 80 min with the limitations of detection (LOD) as low as 64 aM and 89 aM toward microRNA-21 and microRNA-155, respectively.