Date of Award

5-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical and Civil Engineering

First Advisor

Linxia Gu

Second Advisor

Kenia P. Nunes

Third Advisor

Darshan G. Pahinkar

Fourth Advisor

Ashok Pandit

Abstract

Cardiovascular morphogenesis and pathophysiology have been associated with the mechanical properties of the vessel wall. In this work, nanomechanical properties of diseased arteries and control groups were quantified using the Atomic Force Microscopy (AFM). Both tip sizes of 20nm and 5µm were used for examining the local and global stiffness. First, we measured the stiffness as a potential index factor of the mice’s aortic aneurysm. Results have shown the stiffness of mice aortic aneurysm is 58.84 ± 30.26 kPa, which is significantly different (P < 0.05) from the stiffness of the control group of 4.70 ± 17.41 kPa. This was attributed to the degradation of elastin fibers and increment of collagen deposition in the vessel as observed in the histological analysis. The lesion heterogeneity was illustrated by the stiffness gradient from 40 kPa to 1.2 MPa within a 2µm2 region. We also examined the stiffness of the diabetic rat aorta as a potential biomarker for disease progression. Results have shown a significantly higher stiffness of 70.25 ± 14.10 kPa in diabetic rat aorta, compared with 54.19 ± 14.15 kPa in the control group. Lastly, we characterized the human aortic calcifications to fill the knowledge gap of scarce datasets for calcification stiffness. Results have demonstrated the calcification stiffness as 61.5 ± 35 kPa, which is significantly larger than the stiffness of the control group of 12.0 ± 4.4 kPa. The stiffness variation was attributed to the percentage of calcium deposits, observed from the histological analysis. These nanomechanical characterizations could be further used for a better understanding of arterial adaptation and to provide insights for effective vascular therapies.

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