title: Nanocapillary electrokinetic tracking for monitoring charge fluctuations on a single nanoparticle.
abstract: We introduce nanoCapillary Electrokinetic Tracking (nanoCET), an optofluidic platform for continuously measuring the electrophoretic mobility of a single colloidal nanoparticle or macromolecule in vitro with millisecond time resolution and high charge sensitivity. This platform is based on using a nanocapillary optical fiber in which liquids may flow inside a channel embedded inside the light-guiding core and nanoparticles are tracked using elastic light scattering. Using this platform we have experimentally measured the electrophoretic mobility of 60 nm gold nanoparticles in an aqueous environment. Further, using numerical simulations, we demonstrate the underlying electrokinetic dynamics inside the nanocapillary and the necessary steps for extending this method to probing single biomolecules, which can be achieved with existing technologies. This achievement will immensely facilitate the daunting challenge of monitoring biochemical or catalytic reactions on a single entity over a wide range of timescales. The unique measurement capabilities of this platform pave the way for a wide range of discoveries in colloid science, analytical biochemistry, and medical diagnostics.
authors.affiliation: Debye Institute for Nanomaterials Research, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584CC Utrecht, The Netherlands. s.faez@uu.nl.
authors.forename: Sanli
authors.initials: S
authors.lastname: Faez
authors.affiliation: Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584CC Utrecht, The Netherlands.
authors.forename: Sela
authors.initials: S
authors.lastname: Samin
authors.affiliation: Debye Institute for Nanomaterials Research, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584CC Utrecht, The Netherlands. s.faez@uu.nl.
authors.forename: Dashdeleg
authors.initials: D
authors.lastname: Baasanjav
authors.affiliation: Heraeus Quarzglas GmbH and Co. KG, 63450 Hanau, Germany and Leibnitz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07754, Jena, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Weidlich
authors.affiliation: Leibnitz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07754, Jena, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Debye Institute for Nanomaterials Research, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584CC Utrecht, The Netherlands. s.faez@uu.nl.
authors.forename: Allard P
authors.initials: AP
authors.lastname: Mosk