Surface conductivity of biological macromolecules measured by nanopipette dielectrophoresis.
We report the measurement of the surface conductivity of biological macromolecules by dielectrophoretic trapping at the tip of a glass nanopipet. We find that the threshold voltage for trapping is a function of salt concentration and can be directly linked to the effective conductivity of the biomolecule and its solvation shell. The surface conductivities obtained for 20-mer single-stranded DNA, 40-mer double-stranded DNA, and yellow fluorescent protein are 7.9+/-1.9 nS, 5.3+/-0.7 nS, and 21.5+/-1.6 nS, respectively.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, United Kingdom.
Richard W
RW
Clarke
Joe D
JD
Piper
Liming
L
Ying
David
D
Klenerman
D001426:Bacterial Proteins / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004553:Electric Conductivity; D004586:Electrophoresis / Q000379:methods; D008164:Luminescent Proteins / Q000737:chemistry*; D008839:Microelectrodes; D049329:Nanostructures / Q000737:chemistry; D012492:Salts / Q000737:chemistry*
D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D008164:Luminescent Proteins; D012492:Salts; C054562:yellow fluorescent protein, Bacteria; D004247:DNA