Flexible Polymers in Nanopores

Gennes, Pierre‐Gilles de

doi:10.1007/3-540-69711-x_2

Cited by 101 publications

(120 citation statements)

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“…The effects of f front and f back have also been observed in previous studies, 76,83 in which f front and f back are related to the critical flow rate for successful translocation. We further investigate the role of chain conformation on translocation by considering separately the entrance process of the "front" and "back" parts of the star polymer into the nanochannel.…”

Section: B Translocation Dependence On Arm Numbersupporting

confidence: 71%

“…With possible applications for nano-scale self-assembly, the physical properties of star polymers has attracted considerable attention both theoretically [69][70][71][72][73][74][75][76][77][78][79] and experimentally. [80][81][82][83][84] Compared with linear polymers, the translocation process of star polymers through a nanochannel is far more complex due to the change in polymer conformation during translocation.…”

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confidence: 99%

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Conformation-dependent translocation of a star polymer through a nanochannel

Liu

Xiao

et al. 2014

Biomicrofluidics

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The translocation process of star polymers through a nanochannel is investigated by dissipative particle dynamics simulations. The translocation process is strongly influenced by the star arm arrangement as the polymer enters the channel, and a scaling relation between the translocation time [Formula: see text] and the total number of beads N tot is obtained. Qualitative agreements are found with predictions of the nucleation and growth model for linear block co-polymer translocation. In the intermediate stage where the center of the star polymer is at the channel entrance, the translocation time is found to have power law-dependence on the number of arms outside the channel and very weakly dependent on the number of arms in the channel. Increasing the total number of star arms also increases the star translocation time.

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Section: B Translocation Dependence On Arm Numbersupporting

confidence: 71%

mentioning

confidence: 99%

Conformation-dependent translocation of a star polymer through a nanochannel

Liu

Xiao

et al. 2014

Biomicrofluidics

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“…In particular, the quadratic shape of the energy landscape seen here is predicted also for more complex polymers, by scaling arguments2535. It would be interesting to investigate experimentally whether in consequence the statistics of barrier crossing for such more complex polymers also is described by the simple formulas derived here.…”

Section: Discussionmentioning

confidence: 67%

Transition state theory demonstrated at the micron scale with out-of-equilibrium transport in a confined environment

et al. 2016

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Transition state theory (TST) provides a simple interpretation of many thermally activated processes. It applies successfully on timescales and length scales that differ several orders of magnitude: to chemical reactions, breaking of chemical bonds, unfolding of proteins and RNA structures and polymers crossing entropic barriers. Here we apply TST to out-of-equilibrium transport through confined environments: the thermally activated translocation of single DNA molecules over an entropic barrier helped by an external force field. Reaction pathways are effectively one dimensional and so long that they are observable in a microscope. Reaction rates are so slow that transitions are recorded on video. We find sharp transition states that are independent of the applied force, similar to chemical bond rupture, as well as transition states that change location on the reaction pathway with the strength of the applied force. The states of equilibrium and transition are separated by micrometres as compared with angstroms/nanometres for chemical bonds.

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“…While initial entry of only one chain-end (top) may occur rapidly, passage of the entire polymer through the pore is sterically hindered, as the remaining arms must deform for the polymer to pass through;47 a symmetric conformation (bottom) is less likely since multiple chain ends must penetrate the pore at the same time. Once entry has been achieved passage of the polymer would be less hindered than for the asymmetric distribution.…”

Section: Figuresmentioning

confidence: 99%

Soluble Polymer Carriers for the Treatment of Cancer: The Importance of Molecular Architecture

2009

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CONSPECTUS Chemotherapy can destroy tumors and arrest cancer progress. Unfortunately, severe side effects—treatment is usually a series of injections of highly toxic drugs—often restrict the frequency and size of dosages, much to the detriment of tumor inhibition. Most chemotherapeutic drugs have pharmacokinetic profiles with tremendous potential for improvement. Water-soluble polymers offer the potential to increase drug circulation time, improve drug solubility, prolong drug residence time in a tumor, and reduce toxicity. Cytotoxic drugs that are covalently attached to water-soluble polymers via reversible linkages more effectively target tumor tissue than the drugs alone. Macromolecules passively target solid tumor tissue through a combination of reduced renal clearance and exploitation of the enhanced permeation and retention (EPR) effect, which prevails for fast-growing tumors. Effective drug delivery involves a balance between (i) elimination of the polymeric drug conjugate from the bloodstream by the kidneys, liver, and other organs and (ii) movement of the drug out of the blood vasculature and into the tumor (that is, extravasation). Polymers are eliminated in the kidney by filtration through pores with a size comparable to the hydrodynamic diameter of the polymer; in contrast, the openings in the blood vessel structures that traverse tumors are an order of magnitude greater than the diameter of the polymer. Thus, features that may broadly be grouped as the “molecular architecture” of the polymer—such as its hydrodynamic volume (or molecular weight), molecular conformation, chain flexibility, branching, and location of the attached drug—can greatly impact elimination of the polymer from the body through the kidney but have a much smaller effect on the extravasation of the polymer into the tumor. Molecular architecture can in theory be adjusted to assert essentially independent control over elimination and extravasation. Understanding how molecular architecture affects passage of a polymer through a pore is therefore essential for designing polymer drug carriers that are effective in passively delivering a drug payload while conforming to the requirement that the polymers must eventually be eliminated from the body. In this Account, we discuss examples from in vivo studies that demonstrate how polymer architectural features impact the renal filtration of a polymer as well as tumor penetration and tumor accumulation. In brief, features that inhibit passage of a polymer through a pore—such as higher molecular weight, decreased flexibility, and an increased number of polymer chain ends—help prevent elimination of the polymer by the kidneys and can improve blood circulation times and tumor accumulation, thus improving therapeutic effectiveness.

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Flexible Polymers in Nanopores

Cited by 101 publications

References 10 publications

Conformation-dependent translocation of a star polymer through a nanochannel

Conformation-dependent translocation of a star polymer through a nanochannel

Transition state theory demonstrated at the micron scale with out-of-equilibrium transport in a confined environment

Soluble Polymer Carriers for the Treatment of Cancer: The Importance of Molecular Architecture

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