## 1 Introduction  
Iron is the most abundant transition metal in the human body and a vital micronutrient that is a critical component of many crucial enzymes. Therefore, it is essential to various biological processes, such as DNA synthesis and repair, cell cycle regulation, transport of oxygen, and energy production [1]. Iron's catalytic ability harnessed in these crucial enzymes lies in iron's potential to change between various oxidation states, the di-, tri- and, less frequently, the tetravalent oxidation states. The potent redox potential of iron allows it to cycle between these di-, tri- and tetravalent states, which makes it crucial in electron transfer and oxygen transport [2]. However, this strong redox potential allows Fenton chemistry (Figure 1), leading to the production of free radicals and reactive oxygen species (ROS) such as the hydroxyl-radical HO\({}^{\bullet}\), the superoxide radical O\({}_{2}^{\bullet-}\), and hydrogen peroxide H\({}_{2}\)O\({}_{2}\). The free radicals created by the Fenton reaction results in subsequent damage to macromolecules such as DNA, lipids and proteins [3]. When iron is in excess, Fenton chemistry is enhanced, producing ROS, generating organic radicals and aldehyde by-products of lipid and amino acid oxidation. The overproduction of ROS can result in DNA and mitochondrial damage and genetic instability in the cell. Therefore, iron chemistry must be tightly regulated in normal cells to prevent cytotoxicity and normalise cell functions and growth. \[\text{Fe}^{3+}+\text{O}_{2^{c}}\rightarrow\text{Fe}^{2+}+\text{O}_{2}\] (A)  
\[\text{Fe}^{2+}+\text{H}\text{O}_{2}\rightarrow\text{Fe}^{3+}+\text{OH}+\text{OH}\cdot\] (B)  
\(\text{O}_{2^{c}}+\text{H}\text{O}_{2}\rightarrow\text{O}_{2}+\text{OH}+\text{OH}\) in the presence of a Fe catalyst (C)  
Keeping iron levels safe and constant is crucial as conditions of excess or deficiency can lead to diseases such as iron-deficient anaemia and Haemochromatosis, respectively. However, an iron imbalance intracellularly can also lead to neoplastic disease as iron is vital for DNA synthesis and repair, both of which are needed to prevent cancerous changes. For instance, a lack of intracellular iron regulation can result in changes that enhance proliferation, one of the key hallmarks of cancer [4; 5]. A wide variety of iron metabolism proteins play an essential part in tumour progression, the functions of which are required by cancerous cells at relatively higher levels than that of normal cells. Intracellularly iron is commonly bound in heme groups, Fe-S clusters and ferritin. Iron in the form of Fe\({}^{2+}\) is a heme cofactor in both myoglobin and haemoglobin, which are important in oxygen transport in the body, whereas iron clusters participate in electron transfer, play a structural role in DNA enzymes and play iron regulatory roles such as controlling gene expression in response to iron [6]. Iron clusters, [2 Fe-2S], [4 Fe-4S] or [3 Fe-4S], frequently contain an iron centre of Fe\({}^{2+}\) or Fe\({}^{3+}\). These iron clusters play important structural and enzymatic roles in DNA replication and repair and are key components of DNA helicases, primases and polymerases. While iron can be found in these iron clusters, some iron is also present in the cell as a weekly chelate-able pool called the labile iron pool, also known as the redox-active pool or free iron pool. The labile iron pool is mainly a Fe\({}^{2+}\) pool with ions bound to low-affinity ligands; it is this free Fe\({}^{2+}\) that is used in intracellular iron metabolisms and reactions. Thus, the labile iron pool is important in Fenton chemistry and the consequent production of harmful radicals, particularly when the labile iron pool is in excess. Many studies show an increased labile iron pool in various cancerous cells and an increased ferritin expression; however, a direct cause-and-effect relationship has yet to be fully elucidated [7; 8].