Doctor of Philosophy (PhD)



Document Type



Porphyrins and their derivatives are often used as photosensitizers in photodynamic therapy (PDT), which is a noninvasive antitumor treatment. The photochemical process for PDT involves exciting a photosensitizing agent with visible light, which induces cytotoxicity in the presence of oxygen as a result of forming reactive oxygen species (ROS). The ROS are the responsible components for invoking cell death and destruction of tumors. Although this mechanism is an effective cancer therapeutic, it still has many shortcomings. One major challenge of PDT concerns improving the tumor selectivity and specificity of photosensitizers because porphyrins have nonspecific affinity to tumor cells. The discussed research introduces a potential drug delivery vehicle to enhance the efficacy of cancer therapeutics and overcome the aforementioned issues. Specifically, hybrid composite particles composed of superparamagnetic polypeptide-coated silica nanoparticles conjugated to porphyrins were designed to improve the mechanism of tumor cell destruction via controlled assembly and transport. Along the path of developing these nanocomposites, porphyrin self-assembly was explored to understand the dynamics of porphyrins alone. A series of complementary experiments and analytical methods were used, including UV-Vis and fluorescence spectroscopy measurements, small angle X-ray scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM) and freeze-fracture transmission electron microscopy (FF-TEM). Whereas UV-Vis and fluorescence techniques enabled us to determine the type of aggregates formed, AUC and SAXS provided complementary details and information about the size of the assemblies in solution. Cryo-TEM and FF-TEM provided direct visualization of the aggregates.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Vicente, Graca



Included in

Chemistry Commons