Magnetic Nanoparticles for Cancer Therapy

Abstract

Today, technologies based on magnetic nanoparticles (MNPs) are routinely applied to biological systems with diagnostic or therapeutic purposes. The paradigmatic example is the magnetic resonance imaging (MRI), a technique that uses the magnetic moments of MNPs as a disturbance of the proton resonance to obtain images. Similarly, magnetic fluid hyperthermia (MFH) uses MNPs as heat generators to induce localized cell death. The physical basis of these techniques relies on the interaction with external magnetic fields, and therefore the magnetic moment of the particles has to be maximized for these applications. Targeted drug-delivery based on 'smart' nanoparticles is the next step towards more efficient oncologic therapies, by delivering a minimal dose of drug only to the vicinity of the target. Current improvements in this fields relay on a) particle functionalization with specific ligands for targeting cell membrane receptors and b) loading MNPs onto cells (e.g., dendritic cells, T-cells, macrophages) having an active role in tumor grow. Here we review the current state of research on applications of magnetic carriers for cancer therapy, discussing the advances and drawbacks of both passive and targeted delivery of MNPs. The most promising strategies for targeted delivery of MNPs are analyzed, evaluating the expected impact on clinical MRI and MFH protocols.

Magnetic Nanocomposite Devices for Cancer Thermochemotherapy

“…Currently, EM radiation has been considered as a fundamental tool in cancer therapy, especially for diagnosis such as MRI and positron emission tomography (PET) as it is well accepted that EM fields are not especially contraindicated for humans (Goya 2008). The therapeutic potential of EM can be further explored in the magnetic nanothermotherapy and the magnetic field applicators at frequencies and field values are with full compliance to the safety regulations demanded in clinical applications.…”

Cobalt Ferrite Nanoparticles Fabricated via Co-precipitation in Air: Overview of Size Control and Magnetic Properties

“…For each cycle of this loop a quantity of electromagnetic energy proportional to the area of the hysteresis loop is converted to heat in what are called hysteretic losses [60][61]. These hysteretic losses arise from the breaking and forming of domain walls (the walls between magnetic domains) as a result of the magnetization being repeatedly alternated [62]. When these changes happen slower than the applied magnetic field is alternated then heat is generated [13,62].…”

“…These hysteretic losses arise from the breaking and forming of domain walls (the walls between magnetic domains) as a result of the magnetization being repeatedly alternated [62]. When these changes happen slower than the applied magnetic field is alternated then heat is generated [13,62]. Clearly, these hysteretic losses are a potential way to generate the heat required for hyperthermia treatment, however, in practice it has proven difficult to obtain a sufficient heating effect [58,60].…”

“…Clearly, these hysteretic losses are a potential way to generate the heat required for hyperthermia treatment, however, in practice it has proven difficult to obtain a sufficient heating effect [58,60]. Fortunately, there are two other options for magnetic hyperthermia because when an alternating magnetic field alternates direction at a frequency such that the period of the alternating field is less than the magnetic relaxation time of magnetic particles heat is generated [13,60,62]. There are two relaxation times, one is due to Brownian motion, and the other is the Neel relaxation [13,60,62].…”

“…Fortunately, there are two other options for magnetic hyperthermia because when an alternating magnetic field alternates direction at a frequency such that the period of the alternating field is less than the magnetic relaxation time of magnetic particles heat is generated [13,60,62]. There are two relaxation times, one is due to Brownian motion, and the other is the Neel relaxation [13,60,62]. The relaxation time for Brownian motion applies to particles with stable magnetizations such as ferro-and ferrimagnetic particles and it concerns the energy loss as a result of Brownian motion and thus depends on particle motion, the Neel relaxation time concerns single domain particles and the relaxation time required for magnetic spins in single domain particles [29,60,[62][63].…”