title: High-bandwidth protein analysis using solid-state nanopores.
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.
authors: Departments of Physics and Chemistry/Chemical Biology, Northeastern University, Boston, Massachusetts.
authors: Joseph
authors: J
authors: Larkin
authors: Departments of Physics and Chemistry/Chemical Biology, Northeastern University, Boston, Massachusetts.
authors: Robert Y
authors: RY
authors: Henley
authors: Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts.
authors: Murugappan
authors: M
authors: Muthukumar
authors: School of Engineering, Brown University, Providence, Rhode Island.
authors: Jacob K
authors: JK
authors: Rosenstein
authors: Departments of Physics and Chemistry/Chemical Biology, Northeastern University, Boston, Massachusetts. Electronic address: wanunu@neu.edu.
authors: Meni
authors: M
authors: Wanunu
mesh_terms: D000595:Amino Acid Sequence; D015374:Biosensing Techniques / Q000379:methods*; D006195:Hafnium / Q000737:chemistry; D008564:Membrane Potentials; D008567:Membranes, Artificial; D008969:Molecular Sequence Data; D058608:Nanopores; D010087:Oxides / Q000737:chemistry; D010539:Permeability; D011506:Proteins / Q000032:analysis / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry
chemical_list: D008567:Membranes, Artificial; D010087:Oxides; D011506:Proteins; D017655:Silicon Compounds; C545179:hafnium oxide; C032734:silicon nitride; D006195:Hafnium