Nanopore Instrument for Analyzing Single Polymer Molecules in Solution

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Instruments for characterizing individual atoms and molecules have extensive applications in the biological and physical sciences, and play an important role in manufacturing techniques for miniature machines and electronic devices. With the exception of the light microscope, all such instruments work with solid or tethered molecules, and none have the capacity to analyze large numbers of single polymer molecules in solution. Recent work has shown the potential for development of instruments with such capability that are based on nanometer-sized pores (nanopores) in otherwise impermeable membranes. The diameter of the pore permits passage of polymers like DNA, but only one at a time. These existing experimental detectors employ artificial lipid membranes with pores formed by alpha-hemolysin, a naturally occurring proteinaceous toxin. Measurement of the properties of DNA molecules as they transit such pores has shown that the length of individual molecules can be determined rapidly and reliably. To date, these experimental instruments have had limited use because of the difficulty of preparing the membranes and because of the membrane's fragility and short lifetime. This award provides support for development of a new type of nanoporous membrane that can be used as a robust replacement for the alpha-hemolysin membranes. Several strategies to produce the new membranes from mica will be explored, including the use of radiation followed by an acid etch. Mica-based membranes should be exceedingly stable in operation. A successful effort is likely to lead to development of an instrument capable of rapid measurement of the length and number of individual DNA molecules found in mixed populations, and, potentially, to development of an instrument that can perform rapid sequencing of long DNAs without the need for chemical or radioactive labeling procedures.