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Proceedings Paper

Maximum-likelihood position sensing and actively controlled electrokinetic transport for single-molecule trapping
Author(s): Lloyd Davis; Zbigniew Sikorski; William Robinson; Guoqing Shen; Xiaoxuan Li; Brian Canfield; Isaac Lescano; Bruce Bomar; William Hofmeister; James Germann; Jason King; Yelena White; Alexander Terekhov
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Paper Abstract

A freely diffusing single fluorescent molecule may be scrutinized for an extended duration within a confocal microscope by actively trapping it within the femtoliter probe region. We present results from computational models and ongoing experiments that research the use of multi-focal pulse-interleaved excitation with time-gated single photon counting and maximum-likelihood estimation of the position for active control of the electrophoretic and/or electro-osmotic motion that re-centers the molecule and compensates for diffusion. The molecule is held within a region with approximately constant irradiance until it photobleaches and/or is replaced by the next molecule. The same photons used for determining the position within the trap are also available for performing spectroscopic measurements, for applications such as the study of conformational changes of single proteins. Generalization of the trap to multi-wavelength excitation and to spectrally-resolved emission is being developed. Also, the effectiveness of the maximum-likelihood position estimates and semi-empirical algorithms for trap control is discussed.

Paper Details

Date Published: 21 February 2008
PDF: 10 pages
Proc. SPIE 6862, Single Molecule Spectroscopy and Imaging, 68620P (21 February 2008); doi: 10.1117/12.763833
Show Author Affiliations
Lloyd Davis, Univ. of Tennessee Space Institute (United States)
Zbigniew Sikorski, Univ. of Tennessee Space Institute (United States)
William Robinson, Univ. of Tennessee Space Institute (United States)
Guoqing Shen, Univ. of Tennessee Space Institute (United States)
Xiaoxuan Li, Univ. of Tennessee Space Institute (United States)
Brian Canfield, Univ. of Tennessee Space Institute (United States)
Isaac Lescano, Univ. of Tennessee Space Institute (United States)
Bruce Bomar, Univ. of Tennessee Space Institute (United States)
William Hofmeister, Univ. of Tennessee Space Institute (United States)
James Germann, Univ. of Tennessee Space Institute (United States)
Jason King, Univ. of Tennessee Space Institute (United States)
Yelena White, Univ. of Tennessee Space Institute (United States)
Alexander Terekhov, Univ. of Tennessee Space Institute (United States)


Published in SPIE Proceedings Vol. 6862:
Single Molecule Spectroscopy and Imaging
Jörg Enderlein; Zygmunt K. Gryczynski; Rainer Erdmann, Editor(s)

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