Abstract：
:High-bandwidth measurements of the ion current through hafnium oxide and silicon nitride nanopores allow the analysis of sub-30 kD protein molecules with unprecedented time resolution and detection efficiency. Measured capture rates suggest that at moderate transmembrane bias values, a substantial fraction of protein translocation events are detected. Our dwell-time resolution of 2.5 μs enables translocation time distributions to be fit to a first-passage time distribution derived from a 1D diffusion-drift model. The fits yield drift velocities that scale linearly with voltage, consistent with an electrophoretic process. Further, protein diffusion constants (D) are lower than the bulk diffusion constants (D0) by a factor of ~50, and are voltage-independent in the regime tested. We reason that deviations of D from D0 are a result of confinement-driven pore/protein interactions, previously observed in porous systems. A straightforward Kramers model for this inhibited diffusion points to 9- to 12-kJ/mol interactions of the proteins with the nanopore. Reduction of μ and D are found to be material-dependent. Comparison of current-blockage levels of each protein yields volumetric information for the two proteins that is in good agreement with dynamic light scattering measurements. Finally, detection of a protein-protein complex is achieved.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Larkin J,Henley RY,Muthukumar M,Rosenstein JK,Wanunu Mdoi
10.1016/j.bpj.2013.12.025subject
Has Abstractpub_date
2014-02-04 00:00:00pages
696-704issue
3eissn
0006-3495issn
1542-0086pii
S0006-3495(13)05817-7journal_volume
106pub_type
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