Literature Seminar: Iron Oxide Nanoparticles as a Theranostic Agent

May 3, 2017

Patrick Woodworth, Department of Physics, Virginia Commonwealth University

Abstract:

The development of nanoparticles with combined therapeutic, diagnostic and imaging capabilities would greatly impact how we treat many diseases today[1].  An all-in-one agent would allow doctors the ability to monitor, diagnose and treat diseases, such as cancer, quickly and on a case by case basis.  This is the goal of nanotheranostics and why there is great interest in this area of research.  Nanoparticles play a key role in nanomedicine, they can efficiently carry and deliver imaging probes, therapeutic agents, or biological materials to targeted sites.  They also possess active functions that facilitate their use as nanoprobes for imaging/sensing or agents for therapies[2].  Many nanomaterials are already imaging agents and can be easily converted to theranostic agents by the addition of therapeutic functions on them[3].  

Inorganic nanoparticles as carriers offer the advantage of being very stable and highly resistant to degradation.  However, nanotoxicity is a major concern with inorganic nanoparticles containing heavy metal atoms which requires a biocompatible surface coating[2].  Magnetic nanoparticles have been used in many biomedical applications, such as drug and gene delivery, where they are used as nanocarriers for magnetic-field-directed targeting of therapeutic agents to a biologic site of interest. They are also useful for cancer therapy, which involves localized heating produced by coupling these particles to an alternating magnetic field[4].  Specifically iron oxide nanoparticles are quickly becoming the preferred choice in biomedicine due to their biocompatiblity and cost.  Superparamagnetic iron oxide nanoparticles have been extensively utilized for bioseparation, biosensing, and magnetic field assisted drug and gene delivery, as well as for magnetic hyperthermia, and have they have been shown to be excellent contrast agents for MRI's[5].  These particles can be synthesized with a narrow size distribution, making them ideal for probing and manipulating, and can be easily removed from the body.   

In the article by Espinosa et al., they show that iron oxide nanoparticles have the dual capacity to act as both magnetic and photothermal agents.  They chose iron oxide nanocubes for their high efficiency for the magnetic hyperthermia modality itself.  Hyperthermia is used in cancer therapy in which body tissue is exposed to high temperatures, typically with other forms of cancer treatment, such as radiation or chemotherapy.  Photothermal therapy is an experimental cancer treatment mediated by metallic nanoparticles or even semiconducting carbon nanotubes or graphene, which can be activated by near-infrared light, where the absorption of tissues is minimal.  However, both magnetic and photothermal approaches have their disadvantages. Some of these include the fact that high doses of laser irradiation can damage normal tissue and that some of the nanoparticles might be biopersistant and potentially toxic.  In contrast, iron oxide nanoparticles have already been approved for human use in anemia treatments, as magnetic resonance imaging contrast agents and hyperthermia. They also have excellent biodegradibility in vivo, and the iron ions they release upon dissolution can be assimilated by the body.  Exposing the nanocubes to both an alternating magnetic field (hyperthermia) and near-infrared laser irradiation (photothermal therapy) was shown to amplify the heating effect, resulting in reduced tumor growth and in some cases complete tumor regression[1].

REFERENCES:
1.  A. Espinosa, R. Di Corato, J. Kolosnjaj-Tabi, P. Flaud, T. Pellegrino, and C. Wilhelm, "Duality of Iron Oxide Nanoparticles in Cancer Therapy: Amplification of Heating Efficiency by Magnetic Hyperthermia and Photothermal Bimodal Treatment," ACS Nano, vol. 10, no. 2, pp. 2436-2446, Feb. 2016.
2.  G. Chen, I. Roy, C. Yang, and P. N. Prasad, "Nanochemistry and Nanomedicine for Nanoparticle-based Diagnostics and Therapy," Chem. Rev., vol. 116, no. 5, pp. 2826-2885, Mar. 2016.
3.  J. Xie, S. Lee, and X. Chen, "Nanoparticle-based theranostic agents," Adv. Drug Deliv. Rev., vol. 62, no. 11, pp. 1064-1079, Aug. 2010.
4.   A. J. Giustini, A. A. Petryk, S. M. Cassim, J. A. Tate, I. Baker, and P. J. Hoopes, "MAGNETIC NANOPARTICLE HYPERTHERMIA IN CANCER TREATMENT," Nano LIFE, vol. 01, no. 01n02, pp. 17-32, Mar. 2010.
5.  S. M. Janib, A. S. Moses, and J. A. MacKay, "Imaging and drug delivery using theranostic nanoparticles," Adv. Drug Deliv. Rev., vol. 62, no. 11, pp. 1052-1063, Aug. 2010.