title: Characterization of flow direction in microchannels and zebrafish blood vessels by scanning fluorescence correlation spectroscopy.
abstract: The investigation of flow profiles in microstructures and tissues by fluorescence correlation spectroscopy (FCS) has been a challenging topic in the past decade. Due to its inherent optical configuration, a circular focused laser beam, FCS is unable to resolve microfluidic flow directions. Earlier schemes reported the use of two laser beams or the use of nonsymmetrical laser foci to break the symmetry of the measurement system. This, however, is difficult to combine with confocal systems since it would require modifications that interfere with the imaging capabilities. We propose a method called line-scan FCS to measure different flow angles in microchannels and tissues. This method is implemented on a combined laser scanning confocal microscopy (LSCM) and FCS system that enables uncompromised imaging and spectroscopy measurements. We demonstrate that by scanning the laser beam with a defined speed and direction we can measure flow direction with the current system at an optimal resolution of at least 3 microm. The combination system is assessed by measuring flow profiles in a microchannel with and without obstruction. To extend the technique to live tissue measurements we demonstrate that line-scan FCS can determine the flow direction in zebrafish small blood vessels in a label-free approach.
authors.affiliation: National University of Singapore, NUS Graduate Program in Bioengineering, 28 Medical Drive, Singapore 117456, Singapore.
authors.forename: Xiaotao
authors.initials: X
authors.lastname: Pan
authors.forename: Hanry
authors.initials: H
authors.lastname: Yu
authors.forename: Xianke
authors.initials: X
authors.lastname: Shi
authors.forename: Vladimir
authors.initials: V
authors.lastname: Korzh
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wohland
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008833:Microcirculation / Q000502:physiology*; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D018613:Microscopy, Confocal / Q000295:instrumentation* / Q000379:methods; D008856:Microscopy, Fluorescence / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods; D015027:Zebrafish