title: Small-volume rapid-mix device for subsecond kinetic analysis in flow cytometry.
abstract: BACKGROUND
  Rapid-mix flow cytometry has emerged as a powerful tool for mechanistic analysis of ligand binding, cell response, and molecular assembly. Although progress has come from improving sample delivery capabilities, little attention has been paid to the volumetric requirements associated with precious biological reagents.
  
  
  METHODS
  By using programmable syringes, valves, and other fluidic components, we created a modular, precisely regulated rapid-mix device for the delivery of small-volume samples to the flow cytometer. The device was tested using a bead-based assay in which the binding kinetics between native biotin and fluorescein biotin-bearing beads were characterized.
  
  
  RESULTS
  Bead suspensions and reagents paired in 35- to 45-microl aliquots were efficiently mixed by the device and delivered to the flow cytometer. Kinetic data associated with the fluorescein biotin beads were analyzed and used to calibrate the performance characteristics of the device in terms of sample delivery and mixing efficiency.
  
  
  CONCLUSIONS
  The rapid-mix device is capable of detecting subsecond kinetics of biological reactions using microliter volume of samples. Dimensions of the device have been minimized, and the quantitative aspects of sample delivery and analysis have been optimized. Further, the modular design has been optimized for adaptation to a variety of experimental protocols.
authors.affiliation: Department of Chemical and Nuclear Engineering, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.forename: Gordon
authors.initials: G
authors.lastname: Zwartz
authors.forename: Gabriel P
authors.initials: GP
authors.lastname: Lopez
authors.forename: Larry A
authors.initials: LA
authors.lastname: Sklar
authors.forename: Tione
authors.initials: T
authors.lastname: Buranda
mesh_terms: D001710:Biotin / Q000378:metabolism; D005434:Flow Cytometry / Q000295:instrumentation / Q000379:methods; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D019793:Fluorescein / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D008863:Microspheres; D019809:Streptavidin / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D001710:Biotin; D019809:Streptavidin; D019793:Fluorescein