New directions in single polymer dynamics

Abstract

Single polymer techniques are a powerful set of molecular-level tools that enable the direct observation of polymer chain dynamics under highly non-equilibrium conditions. In this way, single polymer methods have been used to uncover fundamentally new information regarding the static and dynamic properties of polymeric materials. However, to achieve the full potential of these new methods, single polymer techniques must be further advanced to enable the study of polymers with complex architectures, heterogeneous chemistries, flexible backbones, and intermolecular interactions in entangled solutions, which reaches far beyond the current state-of-the-art. In this article, we explore recent developments in the area of single polymer physics, including single molecule force spectroscopy and fluorescence microscopy, and we further highlight exciting new directions in the field. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 556-566 KEYWORDS: biopolymer; fluorescence; imaging; rheology; single molecule; single polymer INTRODUCTION Long chain macromolecules play an indispensable role in modern society. Synthetic polymers are used in a wide array of industrial applications, whereas natural polymers facilitate fundamental life processes. The molecular properties of polymer chains ultimately determine the emergent bulk properties of polymeric materials. In particular, the intrinsic chemical and physical properties of polymers, in conjunction with processing conditions, give rise to polymeric materials with desired function. For many years, bulk characterization techniques such as rheometry and light scattering have been used to infer polymer orientation, conformation, and microstructure at equilibrium and during non-equilibrium processing. Recently, single molecule techniques have enabled the direct observation of polymer chains in far-from-equilibrium conditions, thereby providing a window into the molecular structure and behavior of single polymers. In this way, single polymer studies have the potential to reveal fundamentally new information regarding the processing properties and static and dynamic morphology of polymeric materials. However, to achieve the full potential and promise of single molecule techniques, these new methods must be brought to bear on polymers with complex architectures and heterogeneous chemistries, reaching far beyond the current state-of-the-art. In this article, we explore recent advances in single polymer methods and highlight promising new directions in the field.

Stretching self-entangled DNA molecules in elongational fields

“…[3][4][5] Optical tweezers have been used to stretch molecules, 6 and the data were well described by the theory of Marko and Siggia for semiexible chains. These experiments help guide applications such as direct linear analysis 1 or nanopore translocation 2 for sequencing genomes.…”

Single polymer dynamics for molecular rheology

“…Moreover, the extensibility (ratio of contour length to equilibrium size) of DNA is substantially less than that of flexible polymer chains. For example, a double stranded DNA molecule with a con- it should be noted that the elastic force relations of other biological and synthetic flexible polymers have been studied using single molecule force microscopy, which has been reviewed elsewhere [147].…”

Parameter-free prediction of DNA dynamics in planar extensional flow of semidilute solutions

“…Several studies of single molecules of fluorescently labelled DNA have been carried out in order to gain insight into the conformational evolution of polymer chains when subjected to a variety of flow fields [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. These studies have not only enabled the direct visual observation of 'molecular individualism' [8,24], but have also proved to be of vital importance for the validation of molecular theories of polymer dynamics [1,16,17,19,[25][26][27][28][29][30][31].…”