title: Single molecule detection of nitric oxide enabled by d(AT)15 DNA adsorbed to near infrared fluorescent single-walled carbon nanotubes.
abstract: We report the selective detection of single nitric oxide (NO) molecules using a specific DNA sequence of d(AT)(15) oligonucleotides, adsorbed to an array of near-infrared fluorescent semiconducting single-walled carbon nanotubes (AT(15)-SWNT). While SWNT suspended with eight other variant DNA sequences show fluorescence quenching or enhancement from analytes such as dopamine, NADH, L-ascorbic acid, and riboflavin, d(AT)(15) imparts SWNT with a distinct selectivity toward NO. In contrast, the electrostatically neutral polyvinyl alcohol enables no response to nitric oxide, but exhibits fluorescent enhancement to other molecules in the tested library. For AT(15)-SWNT, a stepwise fluorescence decrease is observed when the nanotubes are exposed to NO, reporting the dynamics of single-molecule NO adsorption via SWNT exciton quenching. We describe these quenching traces using a birth-and-death Markov model, and the maximum likelihood estimator of adsorption and desorption rates of NO is derived. Applying the method to simulated traces indicates that the resulting error in the estimated rate constants is less than 5% under our experimental conditions, allowing for calibration using a series of NO concentrations. As expected, the adsorption rate is found to be linearly proportional to NO concentration, and the intrinsic single-site NO adsorption rate constant is 0.001 s(-1) μM NO(-1). The ability to detect nitric oxide quantitatively at the single-molecule level may find applications in new cellular assays for the study of nitric oxide carcinogenesis and chemical signaling, as well as medical diagnostics for inflammation.
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Jingqing
authors.initials: J
authors.lastname: Zhang
authors.forename: Ardemis A
authors.initials: AA
authors.lastname: Boghossian
authors.forename: Paul W
authors.initials: PW
authors.lastname: Barone
authors.forename: Alina
authors.initials: A
authors.lastname: Rwei
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Kim
authors.forename: Dahua
authors.initials: D
authors.lastname: Lin
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Heller
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hilmer
authors.forename: Nitish
authors.initials: N
authors.lastname: Nair
authors.forename: Nigel F
authors.initials: NF
authors.lastname: Reuel
authors.forename: Michael S
authors.initials: MS
authors.lastname: Strano
mesh_terms: D000327:Adsorption; D004247:DNA / Q000737:chemistry*; D005453:Fluorescence; D018625:Microscopy, Atomic Force; D037742:Nanotubes, Carbon; D009569:Nitric Oxide / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared
chemical_list: D037742:Nanotubes, Carbon; D009569:Nitric Oxide; D004247:DNA