Design Maps for the Hyperthermic Treatment of Tumors with Superparamagnetic Nanoparticles

Abstract

A plethora of magnetic nanoparticles has been developed and investigated under different alternating magnetic fields (AMF) for the hyperthermic treatment of malignant tissues. Yet, clinical applications of magnetic hyperthermia are sporadic, mostly due to the low energy conversion efficiency of the metallic nanoparticles and the high tissue concentrations required. Here, we study the hyperthermic performance of commercially available formulations of superparamagnetic iron oxide nanoparticles (SPIOs), with core diameter of 5, 7 and 14 nm, in terms of absolute temperature increase ΔT and specific absorption rate (SAR). These nanoparticles are operated under a broad range of AMF conditions, with frequency f varying between 0.2 and 30 MHz; field strength H ranging from 4 to 10 kA m−1; and concentration cMNP varying from 0.02 to 3.5 mg ml−1. At high frequency field (∼30 MHz), non specific heating dominates and ΔT correlates with the electrical conductivity of the medium. At low frequency field (<1 MHz), non specific heating is negligible and the relaxation of the SPIO within the AMF is the sole energy source. We show that the ΔT of the medium grows linearly with cMNP, whereas the SARMNP of the magnetic nanoparticles is independent of cMNP and varies linearly with f and H2. Using a computational model for heat transport in a biological tissue, the minimum requirements for local hyperthermia (Ttissue >42°C) and thermal ablation (Ttissue >50°C) are derived in terms of cMNP, operating AMF conditions and blood perfusion. The resulting maps can be used to rationally design hyperthermic treatments and identifying the proper route of administration – systemic versus intratumor injection – depending on the magnetic and biodistribution properties of the nanoparticles.

Hemocompatibility and Biomedical Potential of Poly(Gallic Acid) Coated Iron Oxide Nanoparticles for Theranostic Use

“…The obtained SAR values of all the dispersions were nearly identical, around 11 W/g magnetite. This value is fully consistent with others found in the literature, albeit the choice of the parameters of the magnetic field and the magnetization and particle size of the particles among its other relevant properties have tremendous effect on the SAR values [40][41][42][43][44]. The observed heating efficiency of our samples should be sufficient to rise temperature ~5°C above body temperature necessary to induce apoptosis and necrosis of cells in the case when the same particle concentration can be achieved by accumulating them in specific target locations during administration.…”

Enhancing photothermal cancer therapy by clustering gold nanoparticles into spherical polymeric nanoconstructs

“…Different energy sources have been employed to induce the thermal ablation of biological tissues including laser-based techniques [3], radiofrequency systems [4], high-intensity focused ultrasound [5], and alternating magnetic field generators [6]. Some of these approaches have been successfully translated into a clinical setting.…”

Magnetothermoacoustics from magnetic nanoparticles by short bursting or frequency chirped alternating magnetic field: A theoretical feasibility analysis

“…34 It is therefore expected that the thermoacoustic signal generated from a site-specific SPION concentration at a tissue depth of several centimeters by applying a time-domain AMF of practical utility may be more challenging to detect than the photoacoustic signal produced at that depth by a maximum surface illumination used for time-domain photoacoustics. Additionally, at high frequency AMF field (∼30 MHz), nonspecific heating 35 could reduce the expected thermoacoustic signal contrast of the site-specific SPION distribution.…”