Development and Functionalisation of Iron Oxide Nanoparticles and Diatoms for Cancer Therapy: catalytic activity, αPD-L1 antibodies, and incorporation of polyunsaturated lipids for ferroptosis induction

Abstract

Traditional cancer treatments have improved longevity and patent prognosis but come with significant detrimental side effects. Moreover, these treatments rely almost exclusively on induction of apoptosis, but cancer cells are not as sensitive to apoptosis as normal cells and suffer from both intrinsic and acquired drug resistance. Fortunately, advancements in nanomedicine are gaining traction with therapies aimed at specifically targeting cancer cells and providing better treatment efficacy with fewer side effects. Alongside the advancements in nanomedicine, new mechanisms of cell death have been discovered recently. Ferroptosis is a relatively new cell death phenomenon, discovered 10 years ago to which cancer cells are more susceptible than normal cells due to their altered metabolism. Ferroptosis is dependent on iron chemistry and biology, and it is triggered by an imbalance between reactive oxygen species (ROS)homeostasis and metabolism that involves amino acids and lipids. In this process, polyunsaturated fatty acid (PUFA)-containing membrane-localized lipids are the drivers of ferroptosis. Therapy-resistance cancer cells appear to be particularly vulnerable to ferroptosis due to increased demand for iron and the incorporation of PUFA. Thus, there is the possibility that ferroptosis targeting treatments could be more effective and circumvent the issue of cancer cell death resistance. This thesis focuses on ROS generating devices for cancer cell death and the induction of ferroptosis. Iron oxide nanoparticles (IONPs) have been explored for their ROS generating and enzyme-like catalytic properties (e.g. peroxidase-like properties). In this thesis the incorporation of different types of PUFAs, such as the FDA-approved ionisable lipid DLin-MC3-DMA (hereafter referred to as DLIN) and lecithin (which contains multiple unsaturated lipids and PUFA), into different iron oxide encapsulated micelle structures is explored for increased ROS production and peroxidase-like activity leading to enhanced induction of ferroptosis in cancer cells. Successful incorporation of these PUFA-containing molecules into IONPs ranging in shape, size and composition was achieved, and all exhibited good peroxidase-like properties, as demonstrated using a colorimetric method based on 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB)oxidation. Importantly, these IONPs had previously been shown to be effective contrast agents for magnetic resonance imaging and for magnetic hyperthermia, offering the opportunity to combine the ROS generating and peroxidase-like features with in vivo tracking by magnetic resonance imaging (MRI) and/or in combination therapy. Importantly, the incorporation of PUFA-containing molecules resulted in nano devices with increased cancer killing potential. Further investigations into the PUFA incorporated IONPs was conducted leading to a deeper understanding of the ROS generating capabilities and the cytotoxicity