Functionalized Superparamagnetic Iron Oxide Nanoparticles (SPIONs) in Cancer Theranostics

Abstract

Cancer is one of the dreadful diseases, which claimed many lives in the world. Recently, superparamagnetic iron oxide nanoparticles (SPIONs) - particularly magne­tite (Fe3O4)/maghemite (γ-Fe2O3) - have gained a lot of research interest in cancer theranostics for simultaneous cancer diagnosis (via magnetic resonance imaging – MRI – as T2 contrast agents – measured in terms of relaxivity) and cancer therapy (via magnetic fluid hyperthermia (MFH) – as heat inducing agents – measured in terms of specific absorption rate – SAR/intrinsic loss power - ILP), since the SPIONs are chemically stable, biocom­patible, biodegradable and non-toxic to healthy cells, and also show interesting superparamagnetism with high sat­uration magnetization. Moreover, the SPIONs can easi­ly enter into leaky vasculatures of tumor tissues, which make the SPIONs based MRI and MFH techniques as highly efficient with very minimal side effects. The SPIONs can be designed/synthesized followed by in-si­tu- functionalized with robust organic surface coatings and further encapsulated/bio-conjugated with chemo­therapeutic drugs (CHDs) and fluorescence agents for multifunctional applications such as magnetic targeting in cancer drug delivery, bi-modal imaging, and combined thermo-chemo therapy. The imaging/therapeutic effica­cies (i.e., relaxivity/SAR) of the SPIONs in MRI/MFH majorly depend on their magnetic properties, which are significantly influenced by their physicochemical proper­ties such as size/shape, surface coatings, and crystallinity. Therefore, the physicochemical/magnetic properties of the SPIONs should be primarily optimized to enhance their relaxivity/SAR values for attaining better therapeu­tic/imaging efficacies for effective cancer treatments