Electrochemical detection of urinary microRNAs via sulfonamide-bound antisense hybridisation

• Published in: Sensors and actuators. B, Chemical Vol. 253; pp. 335 - 341
• Main Authors: Smith, Daniel A., Newbury, Lucy J., Drago, Guido, Bowen, Timothy, Redman, James E.
• Format: Journal Article
• Language: English
• Published: Switzerland Elsevier B.V 01.12.2017; Elsevier Science Ltd; Elsevier Sequoia
• Subjects: Biomarker; Biomarkers; Biosensor; Biosensors; Bladder; Chemotherapy; Cost analysis; Deoxyribonucleic acid; DNA; Electrochemical analysis; Electrochemistry; Electrodes; Electron transfer; Femtomolar detection; Glassy carbon; Iron cyanides; Medical research; MicroRNAs; Oligonucleotides; Prostate; Reproducibility; Ribonucleic acid; RNA; Sulfonamides; Sulfonic acid; Urinary microRNAs; Urinary tract diseases; Urine; Electrochemistry; Urinary microRNAs; Biomarker; Biosensor; Femtomolar detection
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2017.06.069

•A modified glassy carbon electrochemical sensor for microRNAs was developed.•The electrode allowed detection of femtomolar concentrations of miR-21.•The method was applied to detection of urinary miR-21. Altered serum and plasma microRNA (miRNA) expression profiles have been observed in numerous human diseases, with a number of studies describing circulating miRNA biomarkers for cancer diagnosis, prognosis and response to treatment, and recruitment to clinical trials for miRNA-based drug therapy already underway. Electrochemical detection of biomarkers in urine has several significant advantages over circulating biomarker analysis including safety, cost, speed and ease of conversion to the point of care environment. Consequently, much current research is underway to identify urinary miRNA biomarkers for a variety of pathologies including prostate and bladder malignancies, and renal disorders. We describe here a robust method capable of electrochemical detection of human urinary miRNAs at femtomolar concentrations using a complementary DNA-modified glassy carbon electrode. A miR-21-specific DNA hybridisation probe was immobilised onto a glassy carbon electrode modified by sulfonic acid deposition and subsequent chlorination. In our pilot system, the presence of synthetic mature miR-21 oligonucleotides increased resistance at the probe surface to electron transfer from the ferricyanide/ferrocyanide electrolyte. Response was linear for 10nM–10 fM miR-21, with a limit of detection of 20 fM, and detection discriminated between miR-21, three point-mutated miR-21 sequences, and miR-16. We then demonstrated similar sensitivity and reproducibility of miR-21 detection in urine samples from 5 human control subjects. Our protocol provides a platform for future high-throughput screening of miRNA biomarkers in liquid biopsies.