Magnetic iron oxide nanoparticles are among metal nanoparticles that attract huge attention in many biotechnological fields especially in the biomedical area. Their extensive capabilities and easy separation methodology drive them to be an interesting point to many researchers. Biosynthesis is of a major importance among different methods of nanoparticles production. Microbial synthesis of these nanoparticles by bacteria and yeasts have been reported on a wide scale. However, biosynthesis using halophilic archaea is still in an early stage. This study reveals the first contribution of the haloarchaeon Halobiforma sp. N1 to the nanobiotechnology field. It reports a rapid and economical one-step method of fabricating functionalized superparamagnetic iron oxide nanoparticles and their feasibility for hyperthermia treatment for cancer therapy. Herein, we have focused on optimizing the quantity of these fascinating nanoparticles, obtaining a very high yield of 15 g l−1 with high dispersion in water solution. Their unique characteristics enable them to participate in medical applications. They are nearly spherical in shape with a high degree of homogenity and uniformity with average diameter of 25 ± 9 nm. Also, the magnetic properties and elemental structure of the formed nanoparticles tend to be superparamagnetic like behavior with saturation magnetization of 62 emu g−1 and purity of 98.38% of iron oxide, respectively. The specific absorption rate (SAR) was measured and the particles induced significant heating power at lower frequencies which is a promising result to be applied for in vitro/in vivo hyperthermia studies in the near future.

Ni-Cu nanoparticles have been synthesized by reducing Ni and Cu from metal precursors using a sol–gel route followed by annealing at 300 °C for 1, 2, 3, 6, 8, and 10 h for controlled self-regulating magnetic hyperthermia applications. Particle morphology and crystal structure revealed spherical nanoparticles with a cubic structure and an average size of 50, 60, 53, 87, and 87 nm for as-made and annealed samples at 300 °C for 1, 3, 6, and 10 h, respectively. Moreover, hysteresis loops indicated ferromagnetic behavior with saturation magnetization (Ms) ranging from 13–20 emu/g at 300 K. Additionally, Zero-filed cooled and field cooled (ZFC-FC) curves revealed that each sample contains superparamagnetic nanoparticles with a blocking temperature (TB) of 196–260 K. Their potential use for magnetic hyperthermia was tested under the therapeutic limits of an alternating magnetic field. The samples exhibited a heating rate ranging from 0.1 to 1.7 °C/min and a significant dissipated heating power measured as a specific absorption rate (SAR) of 6–80 W/g. The heating curves saturated after reaching the Curie temperature (Tc), ranging from 30–61 °C within the therapeutic temperature limit. An in vitro cytotoxicity test of these Ni-Cu samples in biological tissues was performed via exposing human breast cancer MDA-MB231 cells to a gradient of concentrations of the sample with 53 nm particles (annealed at 300 °C for 3 h) and reviewing their cytotoxic effects. For low concentrations, this sample showed no toxic effects to the cells, revealing its biocompatibility to be used in the future for in vitro/in vivo magnetic hyperthermia treatment of cancer.

Today, magnetic hyperthermia constitutes a complementary way to cancer treatment. This article reports a promising aspect of magnetic hyperthermia addressing superparamagnetic and highly Fe/Au core-shell nanoparticles. Those nanoparticles were prepared using a wet chemical approach at room temperature. We found that the as-synthesized core shells assembled with spherical morphology, including face-centered-cubic Fe cores coated and Au shells. The high-resolution transmission microscope images (HRTEM) revealed the formation of Fe/Au core/shell nanoparticles. The magnetic properties of the samples showed hysteresis loops with coercivity (HC) close to zero, revealing superparamagnetic-like behavior at room temperature. The saturation magnetization (MS) has the value of 165 emu/g for the as-synthesized sample with a Fe:Au ratio of 2:1. We also studied the feasibility of those core-shell particles for magnetic hyperthermia using different frequencies and different applied alternating magnetic fields. The Fe/Au core-shell nanoparticles achieved a specific absorption rate of 50 W/g under applied alternating magnetic field with amplitude 400 Oe and 304 kHz frequency. Based on our findings, the samples can be used as a promising candidate for magnetic hyperthermia for cancer therapy.

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