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DNA microelectrophoresis using double focus fluorescence correlation spectroscopy
Author(s) -
Bayer Johannes,
Rädler Joachim O.
Publication year - 2006
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500947
Subject(s) - electrokinetic phenomena , microelectrophoresis , fluorescence correlation spectroscopy , electrophoresis , chemistry , microchannel , diffusion , analytical chemistry (journal) , counterion condensation , fick's laws of diffusion , counterion , resolution (logic) , spectroscopy , persistence length , chemical physics , chromatography , materials science , nanotechnology , polymer , thermodynamics , ion , physics , molecule , computer science , organic chemistry , quantum mechanics , artificial intelligence
Double focus fluorescence correlation spectroscopy (dfFCS) was used to determine electrophoretic mobilities of short double‐stranded DNA (dsDNA)‐fragments (75 base pairs (bp) ‐1019 bp) in microfluidic channels. The electrokinetic flow profile across a microchannel was measured with 1 µm spatial resolution and separated in electroosmotic and electrophoretic contributions. Experiments show that the free solution mobility is independent of DNA length. The diffusion constant is additionally determined by FCS and follows a length dependent rod‐diffusion model. We interpret the electrophoretic mobilities using a modified Nernst Einstein relation, which additionally takes Manning condensation and counterion induced hydrodynamic retardation forces into account. In 3% w/v polyethylene oxide (PEO)‐network ( M r 3 ·10 5 Dalton) the electrophoretic velocities become size‐dependent with a power‐law exponent be‐tween 0.28 and 0.31. Mixtures of dsDNA‐fragments exhibit distinguishable peaks in the dfFCS cross‐correlation function. The potential of dfFCS for realtime micro‐analysis in terms of speed and spatial resolution is discussed.