Use this URL to cite or link to this record in EThOS:
Title: Ultrastructure and mechanical changes in multi-scale of sclera following proteoglycan depletion
Author: Zhuola
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2019
Availability of Full Text:
Access from EThOS:
Access from Institution:
The sclera is the dense outer coating of the eye which provides the structural framework that defines the shape of the eye. It is mainly composed of collagen, elastin and interfibrillar proteoglycans. The mechanical properties the sclera have a major impact on healthy function of the eye and are governed by the properties and composition of the microstructural components. For example, biomechanical degradation associated with glaucomatous and myopia occurs alongside a reduction of proteoglycans. The contribution of proteoglycan to the mechanical behaviour of posterior sclera has been studied before. However the distribution of proteoglycan various greatly through all regions of the sclera and the mechanical role of proteoglycan in all scleral region has never been studied. Therefore, this work aims to investigate the contributions of proteoglycan to the structure and mechanical properties of all regions of the sclera, as well as their possible mechanical role in occurs pathology like myopia. In this study, the role of proteoglycan degradation on the tissue ultrastructure, nano- and micromechanical properties of the porcine sclera is studied by several techniques. In vitro enzymatic degradation of proteoglycans was conducted with a-amylase and chondroitinase ABC enzymes. Proteoglycans depleted by the enzymes were characterized by glycosaminoglycan content measurement and proteoglycan protein expression. Collagen fibril morphology and nanomechanical stiffness pre and post enzymes were measured with atomic force microscopy. And the scleral micromechanical properties were measured by nanoindentation technique. DMMB assays indicated that sGAG content was reduced after a-amylase and chondroitinase treatment. And significant variations were found in the scleral protein analyse pattern incubated with both enzymes. These results indicated that both enzymes could cause proteoglycan depletion in the sclera tissue. Scleral topography by AFM results shows that proteoglycan depletion will lead to a reduction of collagen fibrils size, however not affect the collagen fibril D-periodicity. The mechanical results by AFM and nanoindentation show that proteoglycan depletion leads to significant reduction in both nanoscale and microscale mechanical properties of the sclera. However, there are regional differences in both structure and mechanical proteoglycan between results treated with amylase and chondroitinase.
Supervisor: Akhtar, Riaz Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral