Open AccessDNA Conformation Dictates Strength and Flocculation in DNA–Microtubule Composites
Author(s) -
Karthik Peddireddy,
Davide Michieletto,
Gina Aguirre,
Jonathan Garamella,
Pawan Khanal,
Rae M. RobertsonAnderson
Publication year - 2021
Publication title -
acs macro letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.966
H-Index - 92
ISSN - 2161-1653
DOI - 10.1021/acsmacrolett.1c00638
Subject(s) - materials science , polymerization , microrheology , polymer , elasticity (physics) , composite material , microtubule , flocculation , topology (electrical circuits) , chemical physics , chemical engineering , rheology , chemistry , mathematics , combinatorics , engineering , biology , microbiology and biotechnology
Polymer topology has been shown to play a key role in tuning the dynamics of complex fluids and gels. At the same time, polymer composites, ubiquitous in everyday life, have been shown to exhibit emergent desirable mechanical properties not attainable in single-species systems. Yet, how topology impacts the dynamics and structure of polymer composites remains poorly understood. Here, we create composites of rigid rods (microtubules) polymerized within entangled solutions of flexible linear and ring polymers (DNA) of equal length. We couple optical tweezers microrheology with confocal microscopy and scaled particle theory to show that composites with linear DNA exhibit a strongly nonmonotonic dependence of elasticity and stiffness on microtubule concentration due to depletion-driven polymerization and flocculation of microtubules. In contrast, composites containing ring DNA show a much more modest monotonic increase in elastic strength with microtubule concentration, which we demonstrate arises from the decreased conformational size and increased miscibility of rings.