title: Ultrasensitive visual read-out of nucleic acids using electrocatalytic fluid displacement.
abstract: Diagnosis of disease outside of sophisticated laboratories urgently requires low-cost, user-friendly devices. Disposable, instrument-free testing devices are used for home and physician office testing, but are limited in applicability to a small class of highly abundant analytes. Direct, unambiguous visual read-out is an ideal way to deliver a result on a disposable device; however, existing strategies that deliver appropriate sensitivity produce only subtle colour changes. Here we report a new approach, which we term electrocatalytic fluid displacement, where a molecular binding event is transduced into an electrochemical current, which drives the electrodeposition of a metal catalyst. The catalyst promotes bubble formation that displaces a fluid to reveal a high contrast change. We couple the read-out system to a nanostructured microelectrode and demonstrate direct visual detection of 100 fM DNA in 10 min. This represents the lowest limit of detection of nucleic acids reported using high contrast visual read-out.
authors.affiliation: Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada M5S 3G9.
authors.forename: Justin D
authors.initials: JD
authors.lastname: Besant
authors.affiliation: Department of Pharmaceutical Science, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada M5S 3M2.
authors.forename: Jagotamoy
authors.initials: J
authors.lastname: Das
authors.affiliation: Department of Pharmaceutical Science, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada M5S 3M2.
authors.forename: Ian B
authors.initials: IB
authors.lastname: Burgess
authors.affiliation: Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada M5S 3G9.
authors.forename: Wenhan
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Electrical and Computer Engineering, Faculty of Engineering, University of Toronto, Toronto, Canada M5S 3G4.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent
authors.affiliation: 1] Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada M5S 3G9 [2] Department of Pharmaceutical Science, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada M5S 3M2 [3] Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Canada M5S 1A8.
authors.forename: Shana O
authors.initials: SO
authors.lastname: Kelley
mesh_terms: D015374:Biosensing Techniques; D004277:DNA, Single-Stranded / Q000032:analysis*; D055664:Electrochemical Techniques; D004595:Electroplating; D007281:Ink; D008839:Microelectrodes; D049329:Nanostructures; D009696:Nucleic Acids / Q000032:analysis; D010984:Platinum; D014159:Transducers
chemical_list: D004277:DNA, Single-Stranded; D009696:Nucleic Acids; D010984:Platinum