Effect of composite elements on the mechanics of biopolymer networks

Networks of stiff biopolymers, such as collagen type I, are abundant in the human body and provide structural integrity to the skin and internal organs. These networks are known to exhibit mechanical properties that differ significantly from those of synthetic polymers, making them a subject of great interest in research. While pure collagen networks have been extensively studied, collagen in its native state in the extracellular matrix is often found in conjunction with external elements such as polysaccharides, lipids, biological cells, and other fibrous elements and proteins. In this thesis, we investigate the effects of these added components on biopolymer networks using coarse-grained simulations of fiber networks. First, we analyze the impact of the incompressible properties of hyaluronic acid, a polysaccharide embedded in collagen networks by studying how it contributes to a synergistic effect in stiffness of such tissues. This study demonstrates the interplay between diverse mechanical elements and focuses on their rheology. Next, we examine the mechanics of collagen networks embedded with magnetic nanoparticles, focusing on the role of the external magnetic field and the influence of volume fraction of these magnetic particles. Our findings indicate that the combined effects of magnetic fields and external forces resemble stabilizing factors such as bending rigidity and applied temperature and explore how the collective behavior of magnetic particles play an important role in the rheology of such systems. Finally, we explore the effects of thermal fluctuations on three dimensional collagen networks. These fluctuations can stabilize a floppy isostatic network and exhibit non-mean field critical behavior in the mechanical response of networks. While two dimensional networks have been widely studied, real-world biological systems are inherently three-dimensional. Through 3D packing derived networks, we confirm these theoretical predictions for 3D collagen networks.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Engineering

Grantor

Rice University

Year dc:date.issued

2025

Author dc:creator

• Gannavarapu, Anupama

Advisor dc:contributor.advisor

• Mackintosh, Frederick C.

• Collagen
• hyaluronic acid
• fiber networks
• composites
• incompressibility
• rheology
• magnetic nanoparticles
• scaling theory
• thermal fluctuations
• nonaffinity

Statement dc:rights

• Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1911/118423

OAI identifier oai:identifier

oai:repository.rice.edu:1911/118423