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Title: Particle tracking microrheology of fibrillar protein networks
Author: Corrigan, A. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2010
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This thesis uses PTM to study gel formation in a number of systems comprising fibrillar protein aggregates. Methods for studying the spatial heterogeneity in an unbiased way using individual particle information were tested and calibrated. The correlated motion of pairs of particles measures longer lengthscale viscoelasticity. Two-particle measurements were implemented, and a theory was developed to study the random and systematic errors inherent in the measurement. Methods were developed to remove bulk motion such as convection and vibrations from the data, increasing the resolution of PTM. The newly developed techniques were applied to the gelation of β-lactoglobulin, at low concentrations close to the critical gelation concentration. β-lactoglobulin forms amyloid fibrils when exposed to prolonged partially denaturing conditions; the two systems studied in this thesis were pH 2, high temperature (heat-induced) and 50:50 trifluoroethanol:pH 7 phosphate buffer at room temperature (solvent-induced). Using the principle of time-cure superposition, critical exponents were calculated for the two systems and compared with the Rouse and Zimm theories. Deviations were found from the Rouse theory, roughly consistent for the two systems. The concentration dependence was investigated for the solvent-induced system, and two-particle measurements suggested a breakdown of self-similarity in the critical gels at large lengthscales. The heterogeneity was found to increase after gel-formation, as fluctuations in concentration become ‘locked’ into the network. Finally, potential cell culture scaffolds based on self-assembling α-helical coiled-coil peptides were characterised. Modifying the amino acid sequence of the component peptides affects fibre cross-linking and temperature stability, which was followed using PTM. A high level of local heterogeneity was found, which has implications for the application of the systems as cell scaffolds.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available