Simulation of single-molecule trapping in a nanochannel.
The detection and trapping of single fluorescent molecules in solution within a nanochannel is studied using numerical simulations. As optical forces are insufficient for trapping molecules much smaller than the optical wavelength, a means for sensing a molecule's position along the nanochannel and adjusting electrokinetic motion to compensate diffusion is assessed. Fluorescence excitation is provided by two adjacently focused laser beams containing temporally interleaved laser pulses. Photon detection is time-gated, and the displacement of the molecule from the middle of the two foci alters the count rates collected in the two detection channels. An algorithm for feedback control of the electrokinetic motion in response to the timing of photons, to reposition the molecule back toward the middle for trapping and to rapidly reload the trap after a molecule photobleaches or escapes, is evaluated. While accommodating the limited electrokinetic speed and the finite latency of feedback imposed by experimental hardware, the algorithm is shown to be effective for trapping fast-diffusing single-chromophore molecules within a micron-sized confocal region. Studies show that there is an optimum laser power for which loss of molecules from the trap due to either photobleaching or shot-noise fluctuations is minimized.
Robinson
William Neil
WN
University of Tennessee Space Institute, Center for Laser Applications, Tullahoma, Tennessee TN 37388, USA.
Davis
Lloyd M
LM
D001704:Biopolymers / Q000302:isolation & purification* / Q000528:radiation effects*; D003198:Computer Simulation; D008027:Light; D008846:Micromanipulation / Q000379:methods*; D008956:Models, Chemical; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure*; D052898:Optical Tweezers
D001704:Biopolymers
Proc Natl Acad Sci U S A. 2007 Jul 31;104(31):12596-602
17664434
Anal Chem. 2003 Dec 1;75(23):6634-41
14640739
Cell Biochem Biophys. 2007;48(1):1-15
17703064
Biopolymers. 2007 Feb 5;85(2):131-43
17103421
Appl Opt. 1998 Apr 20;37(12):2315-26
18273158
Curr Pharm Biotechnol. 2006 Aug;7(4):287-301
16918405
Opt Express. 2005 Oct 3;13(20):8069-82
19498837
Annu Int Conf IEEE Eng Med Biol Soc. 2009;2009:1396-9
19964522
Microsc Res Tech. 2004 Jan 1;63(1):34-49
14677132
Biotechnol Bioeng. 1990 Feb 20;35(4):327-38
18592527
Curr Pharm Biotechnol. 2003 Dec;4(6):451-62
14683437
Biophys J. 2001 Jun;80(6):2987-99
11371471
Opt Express. 2008 May 12;16(10):6941-56
18545398
Anal Chem. 2008 Dec 15;80(24):9830-4
19072277
Biophys J. 2002 Jun;82(6):3314-29
12023254
Proc Natl Acad Sci U S A. 1997 May 13;94(10):4853-60
9144154
Phys Rev Lett. 2005 Mar 25;94(11):118102
15903893