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Lamontagne M, Levy S. Nonlinear electrophoretic velocity of DNA in slitlike confinement. Phys Rev E 2022; 105:054503. [PMID: 35706241 DOI: 10.1103/physreve.105.054503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 04/20/2022] [Indexed: 06/15/2023]
Abstract
We have applied zero-time-averaged alternating electric fields to DNA molecules in a cross-shaped nanofluidic slit. We observed a net drift of DNA molecules, the magnitude of which depends on the square of the electric field amplitude. From the rate of accumulation of DNA at the center of the device, we derive an estimate for the second-order electrophoretic mobility, μ_{2}. We observe that focusing is absent at a dipole rotation frequency >20 Hz, which suggests that μ_{2} depends on the frequency of the alternating fields. The observation of a nonzero μ_{2} raises the possibility of frequency-dependent electrophoretic DNA separation by length achievable in the absence of a sieving matrix.
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Affiliation(s)
- Michael Lamontagne
- Department of Physics, Applied Physics and Astronomy, Binghamton University, 4400 Vestal Parkway East, P.O. Box 6000, Binghamton, New York 13902-6000, USA
| | - Stephen Levy
- Department of Physics, Applied Physics and Astronomy, Binghamton University, 4400 Vestal Parkway East, P.O. Box 6000, Binghamton, New York 13902-6000, USA
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Teng Y, Andersen NT, Chen JZY. Statistical Properties of a Slit-Confined Wormlike Chain of Finite Length. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00759] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Yue Teng
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Nigel T. Andersen
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Jeff Z. Y. Chen
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Soh BW, Narsimhan V, Klotz AR, Doyle PS. Knots modify the coil-stretch transition in linear DNA polymers. SOFT MATTER 2018; 14:1689-1698. [PMID: 29423476 DOI: 10.1039/c7sm02195j] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We perform single-molecule DNA experiments to investigate the relaxation dynamics of knotted polymers and examine the steady-state behavior of knotted polymers in elongational fields. The occurrence of a knot reduces the relaxation time of a molecule and leads to a shift in the molecule's coil-stretch transition to larger strain rates. We measure chain extension and extension fluctuations as a function of strain rate for unknotted and knotted molecules. The curves for knotted molecules can be collapsed onto the unknotted curves by defining an effective Weissenberg number based on the measured knotted relaxation time in the low extension regime, or a relaxation time based on Rouse/Zimm scaling theories in the high extension regime. Because a knot reduces a molecule's relaxation time, we observe that knot untying near the coil-stretch transition can result in dramatic changes in the molecule's conformation. For example, a knotted molecule at a given strain rate can experience a stretch-coil transition, followed by a coil-stretch transition, after the knot partially or fully unties.
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Affiliation(s)
- Beatrice W Soh
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
| | - Vivek Narsimhan
- Department of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - Alexander R Klotz
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
| | - Patrick S Doyle
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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Dai L, Jones JJ, Klotz AR, Levy S, Doyle PS. Nanoconfinement greatly speeds up the nucleation and the annealing in single-DNA collapse. SOFT MATTER 2017; 13:6363-6371. [PMID: 28868564 DOI: 10.1039/c7sm01249g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Manipulating and measuring single-molecule dynamics and reactions in nanofluidics is a rapidly growing field with broad applications in developing new biotechnologies, understanding nanoconfinement effects in vivo, and exploring new phenomena in confinement. In this work, we investigate the kinetics of DNA collapse in nanoslits using single T4-DNA (165.6 kbp) and λ-DNA (48.5 kbp), with particular focus on the measurement of the nucleation and annealing times. Fixing the ethanol concentration at 35% and varying the slit height from 2000 to 31 nm, the nucleation time dramatically decreases from more than 1 hour to a few minutes or less. The increased collapsed rate results from the larger free energy experienced by coiled DNA in confinement relative to compacted DNA. Our results also shed light on other conformational transitions in confinement, such as protein folding.
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Affiliation(s)
- Liang Dai
- BioSystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology Centre, Singapore 117543, Singapore.
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Ghosal A, Cherayil BJ. The effects of slit-like confinement on flow-induced polymer deformation. J Chem Phys 2017; 147:064905. [PMID: 28810795 DOI: 10.1063/1.4997639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
This paper is broadly concerned with the dynamics of a polymer confined to a rectangular slit of width D and deformed by a planar elongational flow of strength γ̇. It is interested, more specifically, in the nature of the coil-stretch transition that such polymers undergo when the flow strength γ̇ is varied, and in the degree to which this transition is affected by the presence of restrictive boundaries. These issues are explored within the framework of a finitely extensible Rouse model that includes pre-averaged surface-mediated hydrodynamic interactions. Calculations of the chain's steady-state fractional extension x using this model suggest that different modes of relaxation (which are characterized by an integer p) exert different levels of control on the coil-stretch transition. In particular, the location of the transition (as identified from the graph of x versus the Weissenberg number Wi, a dimensionless parameter defined by the product of γ̇ and the time constant τp of a relaxation mode p) is found to vary with the choice of τp. In particular, when τ1 is used in the definition of Wi, the x vs. Wi data for different D lie on a single curve, but when τ3 is used instead (with τ3 > τ1) the corresponding data lie on distinct curves. These findings are in close qualitative agreement with a number of experimental results on confinement effects on DNA stretching in electric fields. Similar D-dependent trends are seen in our calculated force vs. Wi data, but force vs. x data are essentially D-independent and lie on a single curve.
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Affiliation(s)
- Aishani Ghosal
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Binny J Cherayil
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India
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Luzhbin DA, Chen YL. Shifting the Isotropic–Nematic Transition in Very Strongly Confined Semiflexible Polymer Solutions. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00986] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Dmytro A. Luzhbin
- Institute of Physics, Academia Sinica, Taipei, Taiwan, R.O.C
- Department of Chemical Engineering, National Tsing-Hua University, Hsinchu, Taiwan, R.O.C
- Department of Physics, National Taiwan University, Taipei, Taiwan, R.O.C
| | - Yeng-Long Chen
- Institute of Physics, Academia Sinica, Taipei, Taiwan, R.O.C
- Department of Chemical Engineering, National Tsing-Hua University, Hsinchu, Taiwan, R.O.C
- Department of Physics, National Taiwan University, Taipei, Taiwan, R.O.C
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Li X, Dorfman KD. Effect of excluded volume on the force-extension of wormlike chains in slit confinement. J Chem Phys 2016; 144:104902. [PMID: 26979704 DOI: 10.1063/1.4943195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We use pruned-enriched Rosenbluth method simulations to develop a quantitative phase diagram for the stretching of a real wormlike chain confined in a slit. Our simulations confirm the existence of a "confined Pincus" regime in slit confinement, analogous to the Pincus regime in free solution, where excluded volume effects are sensible. The lower bound for the confined Pincus regime in the force-molecular weight plane, as well as the scaling of the extension with force and slit size, agree with an existing scaling theory for this regime. The upper bound of the confined Pincus regime depends on the strength of the confinement. For strong confinement, the confined Pincus regime ends when the contour length in the Pincus blob is too short to have intrablob excluded volume. As a result, the chain statistics become ideal and the confined Pincus regime at low forces is connected directly to ideal chain stretching at large forces. In contrast, for weak confinement, the confined Pincus regime ends when the Pincus blobs no longer fit inside the slit, even though there is sufficient contour length to have excluded volume inside the Pincus blob. As a result, weak confinement leads to a free-solution Pincus regime intervening between the confined Pincus regime for weak forces and ideal chain stretching at strong forces. Our results highlight shortcomings in existing models for the stretching of wormlike chains in slits.
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Affiliation(s)
- Xiaolan Li
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
| | - Kevin D Dorfman
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
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