CHARACTERIZATION OF INDIVIDUAL POLYNUCLEOTIDE MOLECULES USING A MEMBRANE CHANNEL

We show that an electric field can drive single-stranded RNA and DNA m olecules through a 2.6-nm diameter ion channel in a lipid bilayer memb rane. Because the channel diameter can accommodate only a single stran d of RNA or DNA, each polymer traverses the membrane as an extended ch ain that partially blocks the channel. The passage of each molecule is detected as a transient decrease of ionic current whose duration is p roportional to polymer length, Channel blockades can therefore be used to measure polynucleotide length. With further improvements, the meth od could in principle provide direct, high-speed detection of the sequ ence of bases in single molecules of DNA or RNA.