Microrheology to explore protein and cell dynamics

Warren, Rebecca Louisa (2012) Microrheology to explore protein and cell dynamics. PhD thesis, University of Glasgow.

Abstract

In this thesis, I explore the applications of optical tweezers and passive video particle tracking
microrheology for bioanalytical applications.

Microrheology is a branch of rheology that has the same principles as conventional bulk rheology,
but which works on micron length scales. Microrheological techniques relate the free or the driven
motion of micron-sized tracer particles suspended in the fluid under investigation to the ‘elastic’
and ‘viscous’ components of the material. These components can be related to the dynamics of the
molecules that make up the fluid, and thus microrheology has the potential to reveal new
information about the microscopic properties of complex materials.

Optical tweezers are sensitive instruments that have been used to apply forces on the order of pN
and to measure the displacements down to nm of objects ranging in size from 10 nm to over
100μm, making them an essential tool for microrheology. Here, we have developed a new set of
analytical methods for microrheological measurements of biological and bio-analytical systems. In
particular, we have developed two new self-consistent procedures for measuring the linear
viscoelastic properties of materials across the widest frequency range achievable with optical
tweezers (Phys.Review E. (2010) 81:2, and J. Optics (2011) 13:4). Furthermore, we present a
straightforward procedure for measuring the in vivo linear viscoelastic properties of single cells via
passive video particle tracking microrheology of single beads attached to the cells’ exterior.
Notably, the procedure presented here represents an alternative methodology that can be extended
to many experimental formats and provides a simple addition to existing cellular physiology
studies.

In addition, we introduce new methodologies for deriving the concentration scaling laws of
polymer and biopolymer solutions from microrheological measurements carried out with optical
tweezers. These methods have been adopted to investigate the concentration scaling laws of in vitro
reconstituted actin solutions and actin/myosin solutions

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Microrheology, Optical tweezers, Biophysics, Cell dynamics, Cytoskeleton
• Subjects: Q Science > QC Physics; Q Science > Q Science (General)
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Cooper, Professor Jon M. and Tassieri, Dr. Manlio
• Date of Award: 2012
• Depositing User: Miss Rebecca Warren
• Unique ID: glathesis:2012-3344
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 01 May 2012
• Last Modified: 10 Dec 2012 14:06
• URI: https://theses.gla.ac.uk/id/eprint/3344