Iron Oxide-Based Nanostructures for MRI and Magnetic Hyperthermia

Abstract

Many different nanostructures have been developed for biomedical applications to date. Among them, iron oxide nanoparticles have been very prominent in MRI in diagnostic radiology. Nowadays, nanoparticle-based therapeutic applications have gained increased interest, leading to the development of a great variety of different and, in parts, sophisticated nanoparticle formulations. Whereas nanotherapy has been confined to the preclinical phase, magnetic hyperthermia has entered into the clinical phase via controlled studies in patients. Owing to the versatility of nanoparticles, researchers envision the combination of multiple modalities (e.g., targeting, diagnostics and therapy) to one carrier. Nevertheless, such approaches have been challenging due to the necessity of the adaptation of at least partially counteracting parameters between the different modalities, which will be analyzed in this review.

Magnetic Nanoparticles for Precision Oncology: Theranostic Magnetic Iron Oxide Nanoparticles for Image-Guided and Targeted Cancer Therapy

“…It also sensitizes cancer cells to radiation therapy or chemotherapy. Specifically, IONPs could locally convert external high-frequency field energy to thermal energy, which is called magnetic hyperthermia [102][103][104][105]. For example, magnetic hyperthermia mediated by IONPs could increase the temperature at the tumor center to greater than 40°C after exposing to alternating magnetic field [106], resulting in tumor growth inhibition in a human head and neck tumor xenograft model.…”

Means to increase the therapeutic efficiency of magnetic heating of tumors

“…This means that despite the versatility of MNPs, a combination of multiple modalities (e.g. targeting, diagnostics, therapy) to one carrier has distinct limitations [16]. Appropriate imaging of local nanoparticle distributions at the tumor area (e.g.…”

“…For this reason, most of the intravenously injected MNPs are taken up by the mononuclear phagocyte system (MPS; formerly designated as reticulo-endothelial system) before having the opportunity to reach the tumor site. Accordingly, in most cases, < 3% of the injected dose will ultimately reach the tumor site [16]. In this context, people have tried to use polyethylene glycol (PEG) to reduce recognition via the MPS and prolong the blood circulation time.…”

“…In this context, more research should be undertaken to unveil dedicated strategies on how to better modulate the pharmacodynamics of MNPs. More details on this topic can be extracted from [16]. One strategy is the utilization of external magnetic field gradients to concentrate the amount of magnetic materials in the tumor before being cleared by the monocyte phagocyte system.…”

Biological interactions of oxide nanoparticles: The good and the evil

“…5 This allows highly localized thermo-ablation 6 and profi cient photodynamic therapies even in internal tissues due to the transformation of body-penetrating infrared radiation into visible light. 7 These approaches, some of which are already at the stage of clinical trials, increase the effi cacy of anticancer therapies, focusing toxic actions against tumor masses and sparing healthy tissues.…”