This thesis describes the design, synthesis, and testing of novel MRI contrast agents based on iron oxide nanoparticles for the specific detection and identification of vulnerable plaque. Cardiovascular disease remains the leading cause of death worldwide, primarily due to heart attacks and strokes resulting from vulnerable plaque rupture. Vulnerable plaque occurs in atherosclerosis, when plaque is deposited in the walls of blood vessels and can take on vulnerable or stable phenotypes. There is an urgent need for an imaging biomarker to enable the specific detection of vulnerable plaque to facilitate treatment and prevent future heart attacks and strokes. MRI is a non-ionising, non-invasive imaging modality with the potential for highly customisable contrast agents.
Chapter 2 discusses the design and synthesis of a library of superparamagnetic iron oxide nanoparticle-based contrast agents through thermal decomposition and coating with different surface ligands, including poly (maleic anhydride-alt-1-octadecene), alendronate, and poly (ethyleneimine). The agents were characterised through transmission electron microscopy, dynamic light scattering, zeta potential and relaxivity measurements.
Chapter 3 presents the results of biological tests performed using the lead candidate from the synthesis carried out in chapter 2, including the coupling of a targeting antibody to the contrast agent, in vitro testing, and MR imaging in a preclinical model with histological verification of the results.
Chapter 4 builds on the initial design and synthetic work of Chapter 2 with the introduction of a gold shell, moving towards multi-modality imaging. Several synthetic routes for the introduction of the gold shell and a selection of surface ligands including poly (maleic anhydride-alt-1-octadecene), homocysteine, and citrate were studied, and characterised through transmission electron microscopy, dynamic light scattering, and zeta potential measurements.
Chapter 5 summarises the conclusions of the project, presents potential areas for future work and concludes the thesis.