Clarke Richard W, Piper Joe D, Ying Liming, Klenerman David
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, United Kingdom.
Phys Rev Lett. 2007 May 11;98(19):198102. doi: 10.1103/PhysRevLett.98.198102. Epub 2007 May 9.
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.
