Polymer translocation

A reflection of the significant advances in the field, this book discusses the macromolecular basis of polymer translocation that have emerged based on experimentation, new models, and computational approaches. Polymer translocation occurs in many biological and biotechnological phenomena where electrically charged polymer molecules move through narrow spaces in crowded environments. Unraveling the rich phenomenology of polymer translocation requires a grasp of modern concepts of polymer physics and polyelectrolyte behavior. Polymer Translocation discusses universal features of polymer translocations and summarizes the key concepts of polyelectrolyte structures, electrolyte solutions, ionic flow, mobility of charged macromolecules, polymer capture by pores, and threading of macromolecules through pores. With approximately 150 illustrations and 850 equations, the book: Avoids heavy mathematics Uses examples to illustrate the richness of the phenomenon Introduces the entropic barrier idea behind polymer translocation Outlines conceptual components necessary for a molecular understanding of polymer translocation Provides mathematical formulas for the various quantities pertinent to polymer translocation The challenge in understanding the complex behavior of translocation of polyelectrolyte molecules arises from three long-range forces due to chain connectivity, electrostatic interactions, and hydrodynamic interactions. Polymer Translocation provides an overview of fundamentals, established experimental facts, and important concepts necessary to understand polymer translocation. Readers will gain detailed strategies for applying these concepts and formulas to the design of new experiments Content: General Premise Biological contexts Single-molecule experiments Nomenclature Entropic barrier idea Physics of translocation Outlook Size, Shape, and Structure of Macromolecules Measures of polymer conformations Universal behavior Excluded volume interaction Coarse-grained models of chain connectivity Chain swelling by excluded volume effect Coil-globule transition Concentration effects Summary Electrolyte Solutions, Interfaces, and Geometric Objects Electrolyte solutions Charged interfaces Summary Flexible and Semiflexible Polyelectrolytes Concepts Experimental results Simulation results Electrostatic swelling with fixed polymer charge Self-regularization of polymer charge Concentration effects Summary Confinement, Entropic Barrier, and Free Energy Landscape Hole in a wall Spherical cavities Cylindrical pores Infinitely wide channels Summary Random Walks, Brownian Motion, and Drift Biased random walk Brownian motion and Langevin equation Fokker-Planck-Smoluchowski equation Collection of Brownian particles Equilibrium versus steady state Finite boundaries and first passage time Properties of drift-diffusion process Summary Polyelectrolyte Dynamics Solvent continuum and hydrodynamic interaction Uncharged polymer Diffusion of polyelectrolyte chains Electrophoretic mobility Coil-stretch under flow Summary Ion Flow in Single Pores A general scenario Equilibrium Steady state without diffusion Steady state with drift and diffusion Effect of barriers Ionic current through protein pores Fluctuations in ionic current Electroosmotic flow (EOF) Summary Polymer Capture Representative experimental results General considerations Diffusion-limited capture Drift-limited regime Effect of convective flow Polymer capture with electroosmotic flow Effect of barriers on capture rate Summary Translocation Kinetics: Nucleation and Threading Representative experimental results Insights from simulations Theory of translocation kinetics Comparison between experimental data and theory Summary Further Issues Non-equilibrium conformations during threading Amplification of chemical details Biological examples Summary