We demonstrate a method for simultaneous real-time electrical and single-molecule optical recordings of the interactions between single-stranded DNA and nanoscopic pores in planar lipid membranes. Electrophysiological techniques are used to measure the conductance of individual or many ion channels in a membrane. Confocal fluorescence microscopy is used to acquire rapid and complementary optical information at, or near, the single-molecule level. Biotinylated DNA and fluorescently-labeled streptavidin is used to produce a complex that can be driven into and subsequently ejected from the alpha hemolysin ion channel by an applied transmembrane voltage. Simultaneous optical and electrical recording provides two independent methods for probing nanopore occupancy by biopolymers and reveals nonspecific interactions between the DNA complexes and the lipid membrane. Fluoresence correlation spectroscopy is used to determine the number density and diffusion constants of membrane-associated complexes. The results demonstrate the application of simultaneously-acquired data within the context of nanopore-0based sensors and the decoding fo information stored in biomacromolecules.
Pub Type: Journals
alpha hemolysin, biopolymer, biotechnology, DNA FCS, electrophysiology, fluorescent probe, nanopore, sensor, transport