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3D single-molecule tracking enables direct hybridization kinetics measurement in solution
Cong Liu1, Judy M Obliosca, Yen-Liang Liu
1Department of Biomedical Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, Texas 78712, USA. tim.yeh@austin.utexas.edu.
Nanoscale
|April 20, 2017
Summary
This study introduces a novel 3D single-molecule tracking method to observe DNA hybridization in solution. The technique accurately measures annealing and melting rates, providing real-time insights into molecular interactions without surface or trap interference.
Area of Science:
- Biophysics
- Molecular Biology
- Analytical Chemistry
Background:
- Traditional single-molecule DNA hybridization studies are limited by surface immobilization or trapping.
- Observing freely diffusing molecules in solution presents challenges in tracking and kinetic analysis.
Purpose of the Study:
- To develop and validate a time-resolved 3D single-molecule tracking (3D-SMT) method for studying DNA hybridization kinetics in solution.
- To enable observation of multiple annealing and melting events on the same freely diffusing DNA molecule.
Main Methods:
- Combines confocal-feedback 3D-SMT with time-domain fluorescence lifetime measurement.
- Utilizes fluorescence lifetime as an indicator of DNA hybridization.
- Achieves sub-diffraction-limit spatial resolution and 15 ms temporal resolution.
Main Results:
- Successfully characterized annealing rate (kon), melting rate (koff), and association constant (Ka) for an 8 bp DNA duplex.
- Demonstrated accurate kinetic measurements in solution, free from photobleaching and diffusion artifacts.
- Showcased capability for kinetic measurements in low signal-to-noise conditions (SNR ≈ 1.4).
Conclusions:
- The developed 3D-SMT method offers a robust platform for precise single-molecule DNA hybridization kinetic measurements in solution.
- The technique overcomes limitations of previous methods, providing more accurate and comprehensive kinetic data.
- Enables characterization of hybridization kinetics over a broad range, advancing the understanding of molecular interactions.