title: In situmicrofluidic dialysis for biological small-angle X-ray scattering.
abstract: Owing to the demand for low sample consumption and automated sample changing capabilities at synchrotron small-angle X-ray (solution) scattering (SAXS) beamlines, X-ray microfluidics is receiving continuously increasing attention. Here, a remote-controlled microfluidic device is presented for simultaneous SAXS and ultraviolet absorption measurements during protein dialysis, integrated directly on a SAXS beamline. Microfluidic dialysis can be used for monitoring structural changes in response to buffer exchange or, as demonstrated, protein concentration. By collecting X-ray data during the concentration procedure, the risk of inducing protein aggregation due to excessive concentration and storage is eliminated, resulting in reduced sample consumption and improved data quality. The proof of concept demonstrates the effect of halted or continuous flow in the microfluidic device. No sample aggregation was induced by the concentration process at the levels achieved in these experiments. Simulations of fluid dynamics and transport properties within the device strongly suggest that aggregates, and possibly even higher-order oligomers, are preferentially retained by the device, resulting in incidental sample purification. Hence, this versatile microfluidic device enables investigation of experimentally induced structural changes under dynamically controllable sample conditions.
authors.affiliation: Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Magda
authors.initials: M
authors.lastname: Skou
authors.affiliation: Department of Structural Biophysics, University of Copenhagen, Universitetsparken 6, DK-2100 Copenhagen, Denmark ; MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853, USA.
authors.forename: Søren
authors.initials: S
authors.lastname: Skou
authors.affiliation: Department of Micro- and Nanotechnology, The Technical University of Denmark, Ørsteds plads, 2800 Kongens Lyngby, Denmark.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Jensen
authors.affiliation: Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Bente
authors.initials: B
authors.lastname: Vestergaard
authors.affiliation: MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853, USA.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Gillilan
keywords: SAXS; buffer exchange; dialysis; microfluidics; protein solution concentration