title: Ion-Switchable Quantum Dot Förster Resonance Energy Transfer Rates in Ratiometric Potassium Sensors.
abstract: The tools for optically imaging cellular potassium concentrations in real-time are currently limited to a small set of molecular indicator dyes. Quantum dot-based nanosensors are more photostable and tunable than organic indicators, but previous designs have fallen short in size, sensitivity, and selectivity. Here, we introduce a small, sensitive, and selective nanosensor for potassium measurements. A dynamic quencher modulates the fluorescence emitted by two different quantum dot species to produce a ratiometric signal. We characterized the potassium-modulated sensor properties and investigated the photonic interactions within the sensors. The quencher's protonation changes in response to potassium, which modulates its Förster radiative energy transfer rate and the corresponding interaction radii with each quantum dot species. The nanosensors respond to changes in potassium concentrations typical of the cellular environment and thus provide a promising tool for imaging potassium fluxes during biological events.
authors.affiliation: Department of Pharmaceutical Sciences, Northeastern University , 360 Huntington Avenue, Boston, Massachusetts 02115, United States.
authors.forename: Timothy T
authors.initials: TT
authors.lastname: Ruckh
authors.affiliation: Department of Pharmaceutical Sciences, Northeastern University , 360 Huntington Avenue, Boston, Massachusetts 02115, United States.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Skipwith
authors.forename: Wendi
authors.initials: W
authors.lastname: Chang
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Senko
authors.forename: Vladimir
authors.initials: V
authors.lastname: Bulovic
authors.forename: Polina O
authors.initials: PO
authors.lastname: Anikeeva
authors.affiliation: Department of Pharmaceutical Sciences, Northeastern University , 360 Huntington Avenue, Boston, Massachusetts 02115, United States.
authors.forename: Heather A
authors.initials: HA
authors.lastname: Clark
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000032:analysis; D057809:HEK293 Cells; D006801:Humans; D007477:Ions / Q000737:chemistry; D007700:Kinetics; D018613:Microscopy, Confocal; D061848:Optical Imaging; D010316:Particle Size; D011188:Potassium / Q000032:analysis*; D045663:Quantum Dots / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D005456:Fluorescent Dyes; D007477:Ions; D011188:Potassium
keywords: FRET; ion sensing; nanosensor; optode; quantum dot