John Kasianowicz: "High-Resolution Separation of Analytes with Nanopores"

High-Resolution Separation of Analytes with Nanopores

Over the past two decades, we demonstrated that single nanometer-scale pores can detect, characterize, and identify a wide range of analytes at the single molecule level, and suggested the method might enable DNA sequencing in a ticker-tape like fashion. To aid the development of this and other analytical applications, we addressed several issues: the need for interactions between the analyte and nanopore, and the measurement resolving power. Critical tests were performed with synthetic poly(ethylene glycol) polymers, which reduce the Staphylococcus aureus α-hemolysin ion channel’s ionic conductance. Our analytical theory, refined by computer simulations, shows the decrease in conductance and the mean residence time of the polymer in the pore depend on the molecule’s size and charge. The system is capable of separating molecules at high resolution, and forms the basis for a new nanopore-based method for sequencing DNA. Specifically, instead of discriminating between subtle differences in size between small DNA mononucleotides, the measurement is reduced to sizing easily separable polymer tags released via a sequencing by synthesis approach. I will also discuss our recent work that shows how nanopores could be used to study the thermodynamic and kinetic properties of single molecules.