Author: Aristeidis PapagiannopoulosPublisher:
ISBN:
Category :
Languages : en
Pages : 440
Book Description
The Structure and Dynamics of Polyelectrolyte Combs
Author: Aristeidis PapagiannopoulosPublisher:
ISBN:
Category :
Languages : en
Pages : 440
Book Description
Structure and Dynamics of Confined Polymers
Author: John J. KasianowiczPublisher: Springer Science & Business Media
ISBN: 9781402006975
Category : Science
Languages : en
Pages : 46
Book Description
Polymers are essential to biology because they can have enough stable degrees of freedom to store the molecular code of heredity and to express the sequences needed to manufacture new molecules. Through these they perform or control virtually every function in life. Although some biopolymers are created and spend their entire career in the relatively large free space inside cells or organelles, many biopolymers must migrate through a narrow passageway to get to their targeted destination. This suggests the questions: How does confining a polymer affect its behavior and function? What does that tell us about the interactions between the monomers that comprise the polymer and the molecules that confine it? Can we design and build devices that mimic the functions of these nanoscale systems? The NATO Advanced Research Workshop brought together for four days in Bikal, Hungary over forty experts in experimental and theoretical biophysics, molecular biology, biophysical chemistry, and biochemistry interested in these questions. Their papers collected in this book provide insight on biological processes involving confinement and form a basis for new biotechnological applications using polymers. In his paper Edmund DiMarzio asks: What is so special about polymers? Why are polymers so prevalent in living things? The chemist says the reason is that a protein made of N amino acids can have any of 20 different kinds at each position along the chain, resulting in 20 N different polymers, and that the complexity of life lies in this variety.
A Study of Structure and Dynamics of Polyelectrolyte Solutions Using Flow Birefringence Measurements
Author: Shih Ping ChenDynamics and Structure of Polyelectrolyte Complexes
Author: Hamidreza Shojaei-MahibPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Interaction of charged macromolecules among themselves and with charged interfaces in salty aqueous medium is a common phenomenon prevalent in biology and synthetic systems. We have addressed several inter-related issues in this general context. First we present a theory of adsorption of polyelectrolytes on the interior and exterior surfaces of a charged spherical vesicle. We derive the critical adsorption condition and the density profile of the polymer in terms of various characteristics of the polymer, vesicle, and the solution, such as the length and charge density of polymer, the radius and charge of the vesicle, the salt concentration of the solution, and the dielectric constant of the solvent. We have used the Wentzel-Kramers-Brillouin (WKB) method to solve the equation for the probability distribution function of the chain. For the polyelectrolyte inside the vesicle, the competition between the loss of conformational entropy and the attractive electrostatic energy between the vesicle and the polyelectrolyte, results in two different encapsulated states. By considering the adsorption from outside, we calculate the entropic and the energetic contributions to the free energy for the polymer being adsorbed in the interior and exterior states and the free energy penalty for the polyelectrolyte being expelled from the vesicle. The kinetics of the polyelectrolyte complexation have been studied using the Smoluchowski equation. We derive the mean distance between two oppositely charged polyelectrolytes and the reaction rate for the complexation in terms of the salt concentration and polyelectrolyte characteristics. We also calculate the half-time for the complexation process at different salt concentrations and initial distances.\\ For a vesicle, we have derived the free energy landscape of translocation through the pore by accounting for the energy penalty of bending and stretching the vesicle from due to deformation by pore. Using the Fokker-Planck formalism, we have calculated the average translocation time corresponding to the various free energy landscapes representing different parameter sets. We also discuss the dependencies of the average translocation time on the strength of the external force, vesicle size, bending and stretching moduli of the vesicle, and the radius and length of the pore. Finally, we formulate a theory of the effects of long-range interactions on surface tension and spontaneous curvature of proteinaceous shells based on the general Deryaguin-Landau-Verwey-Overbeek (DLVO) theory. we have derived the renormalized spontaneous curvature as a function of capsid's inner and outer charge density and solution properties.
Microrheology with Optical Tweezers
Author: Manlio TassieriPublisher: CRC Press
ISBN: 1315341220
Category : Science
Languages : en
Pages : 356
Book Description
Thanks to the pioneering works of Ashkin and coworkers, optical tweezers (OTs) have become an invaluable tool for myriad studies throughout the natural sciences. Their success relies on the fact that they can be considered as exceptionally sensitive transducers that are able to resolve pN forces and nm displacements, with high temporal resolution, down to μs. Hence their application to study a wide range of biological phenomena such as measuring the compliance of bacterial tails, the forces exerted by a single motor protein, and the mechanical properties of human red blood cells and of individual biological molecules. The number of articles related to them totals to a whopping 58,000 (source Google Scholar)! Microrheology is a branch of rheology, but it works at micrometer length scales and with microliter sample volumes. Therefore, microrheology techniques have been revealed to be very useful tools for all those rheological/mechanical studies where rare or precious materials are employed, such as in biological and biomedical studies. The aim of this book is to provide a pedagogical introduction to the physics principles governing both the optical tweezers and their application in the field of microrheology of complex materials. This is achieved by following a linear path that starts from a narrative introduction of the "nature of light," followed by a rigorous description of the fundamental equations governing the propagation of light through matter. Moreover, some of the many possible instrumental configurations are presented, especially those that better adapt to perform microrheology measurements. In order to better appreciate the microrheological methods with optical tweezers explored in this book, informative introductions to the basic concepts of linear rheology, statistical mechanics, and the most popular microrheology techniques are also given. Furthermore, an enlightening prologue to the general applications of optical tweezers different from rheological purposes is provided at the end of the book.
The Structure and Dynamics of Hydrophobically Modified Polyelectrolytes
Author: Emanuela Di ColaOn the Structure and Dynamics of Polyelectrolyte Gel Systems and Gel-surfactant Complexes
Author: Per Johan RåsmarkPublisher:
ISBN: 9789155460839
Category :
Languages : en
Pages : 71
Book Description
The Dynamics and Structure of Polyelectrolyte and Microgel
Author: Kehua LinPublisher:
ISBN:
Category : Materials science
Languages : en
Pages : 94
Book Description
Polyelectrolyte and microgel were used as a model to investigate the structure and dynamics of complex liquid. In chapter 2, a coacervate system that is associated with net neutral polybetaine and cationic P2VP was applied in this research work as an environment for polyelectrolyte whose confirmation is characterized by fluorescence correlation spectroscopy. Surprisingly, the chain confirmation of the positive charged polyelectrolyte, P2VP, behaves oppositely compared to that in dilute solution. With the increased pH, the chain remains swollen upon coacervation or even slightly more expanded while the chain would collapse due to the low charge density at high pH. Schematic illustration of f-P2VP and the phase behavior is further investigated. In chapter 3 and 4, the spatial confinement of the microgel system suspension at near supercool region and supercool region under different confinement wall was investigated under confocal microscope and the dynamics was further extracted by image analysis. We found the softer wall can weaken the confinement effect and result in a higher mobility, even for the hard microgel suspension. The onsite height of confinement effect is increase with decreased stiffness of the wall. The mobile cluster which treated as dynamics structure and the pair correlation function under different surface confinement was further investigated. The size of mobile cluster decreased and a more disorder structure is observed when stiffness of the confinement wall reduced.
Author: Amit Sehgal
Author: Brett David Ermi