Nanochannel-Based Single Molecule Recycling

• Published in: Nano letters Vol. 12; no. 6; pp. 3273 - 3278
• Main Authors: Lesoine, John F, Venkataraman, Prahnesh A, Maloney, Peter C, Dumont, Mark E, Novotny, Lukas
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13.06.2012
• Subjects: Condensed matter: structure, mechanical and thermal properties; Diffusion coefficient; Diffusion in nanoscale solids; Diffusion in solids; Dynamic tests; Electric potential; Energy transfer; Exact sciences and technology; Fluorescence; Lasers; Molecular Imaging - methods; Nanoparticles - analysis; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Nanostructure; Physics; Recycling; Spectrometry, Fluorescence - methods; Transit time; Transport properties of condensed matter (nonelectronic); FRET; Single molecule detection; trapping; electroosmosis; nanofluidics; Proteins; Trapping; Experimental design; DNA; Macromolecules; Fluorescence; Immobilization; Diffusion coefficient; Silica; Energy transfer
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl301341m

We present a method for measuring the fluorescence from a single molecule hundreds of times without surface immobilization. The approach is based on the use of electroosmosis to repeatedly drive a single target molecule in a fused silica nanochannel through a stationary laser focus. Single molecule fluorescence detected during the transit time through the laser focus is used to repeatedly reverse the electrical potential controlling the flow direction. Our method does not rely on continuous observation and therefore is less susceptible to fluorescence blinking than existing fluorescence-based trapping schemes. The variation in the turnaround times can be used to measure the diffusion coefficient on a single molecule level. We demonstrate the ability to recycle both proteins and DNA in nanochannels and show that the procedure can be combined with single-pair Förster energy transfer. Nanochannel-based single molecule recycling holds promise for studying conformational dynamics on the same single molecule in solution and without surface tethering.