title: Electrochemiluminescence on digital microfluidics for microRNA analysis.
abstract: Electrochemiluminescence (ECL) is a sensitive analytical technique with great promise for biological applications, especially when combined with microfluidics. Here, we report the first integration of ECL with digital microfluidics (DMF). ECL detectors were fabricated into the ITO-coated top plates of DMF devices, allowing for the generation of light from electrically excited luminophores in sample droplets. The new system was characterized by making electrochemical and ECL measurements of soluble mixtures of tris(phenanthroline)ruthenium(II) and tripropylamine (TPA) solutions. The system was then validated by application to an oligonucleotide hybridization assay, using magnetic particles bearing 21-mer, deoxyribose analogues of the complement to microRNA-143 (miRNA-143). The system detects single nucleotide mismatches with high specificity, and has a limit of detection of 1.5 femtomoles. The system is capable of detecting miRNA-143 in cancer cell lysates, allowing for the discrimination between the MCF-7 (less aggressive) and MDA-MB-231 (more aggressive) cell lines. We propose that DMF-ECL represents a valuable new tool in the microfluidics toolbox for a wide variety of applications.
authors.affiliation: Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1.
authors.forename: Mohtashim H
authors.initials: MH
authors.lastname: Shamsi
authors.affiliation: Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1.
authors.forename: Kihwan
authors.initials: K
authors.lastname: Choi
authors.affiliation: Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON, Canada M5S 3G9.
authors.forename: Alphonsus H C
authors.initials: AH
authors.lastname: Ng
authors.affiliation: Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1.
authors.forename: M Dean
authors.initials: MD
authors.lastname: Chamberlain
authors.affiliation: Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON, Canada M5S 3G9. Electronic address: aaron.wheeler@utoronto.ca.
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Wheeler
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D056656:Lab-On-A-Chip Devices; D008163:Luminescent Measurements / Q000295:instrumentation*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism*; D009374:Neoplasms, Experimental / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation
chemical_list: D014408:Biomarkers, Tumor; D035683:MicroRNAs
keywords: Digital microfluidics; Electrochemiluminescence; MicroRNA; Single nucleotide mismatch; Tumor cells