Single Molecule Imaging of Protein Molecules in Nanopores

TitleSingle Molecule Imaging of Protein Molecules in Nanopores
Publication TypeJournal Article
Year of Publication2010
AuthorsMa CB, Yeung ES
Journal TitleAnalytical Chemistry
Date Published01/15
ISBN Number0003-2700
Accession NumberISI:000273484200006
Keywordscapillary-electrophoresis, DNA-MOLECULES, fluorescence microscopy, individual molecules, lateral diffusion, liquid/solid interfaces, nanotube membranes, SELF-ASSEMBLED MONOLAYERS, size-exclusion chromatography, ultrafiltration membranes

The interactions between single protein molecules and nanoporous polycarbonate membranes were investigated at the single molecule level. Entrapment of proteins was shown to be size selective and was dependent on the membrane pore diameter. A pore size that is only slightly larger than the maximum dimension of the proteins was inadequate for intrusion into the pores. For a given protein, the number of molecules found at a given depth decreased as the pore size decreased. In addition, as the depth increased, for a given size pore, the number of molecules decreased rapidly. The depth-dependent histograms nicely fit a one-dimensional diffusion model. However, a highly restricted motion was observed even when the pore diameter was 10 times the size of the protein, resulting in anomalously small diffusion coefficients. We also demonstrated the subtle differences in depth distribution among BSA and hemoglobin that have nearly the same molecular weight but slightly different molecular shapes. These results give unique insights into the detailed mechanism of size-exclusion chromatography and membrane filtration.

URL<Go to ISI>://000273484200006