Facile one-pot chemical approach for synthesis of monodisperse chain-like superparamagnetic maghemite (γ-Fe2O3) nanoparticles

Feasibility Study of a Novel Magnetic Bone Cement for the Treatment of Bone Metastases

Bone cement is a crucial material to treat bone metastases defects, and can fill the bone defect and provide mechanical support simultaneously, but the antitumor effect is very limited. Magnetic bone cement not only supports bone metastasis defects but can also achieve magnetic hyperthermia to eliminate tumor cells around the bone defect. However, the physicochemical properties of the bone cement matrix will change if the weight ratio of the magnetic nanoparticles in the cement is too high. We mixed 1 weight percent Zn_0.3Fe_2.7O₄ with good biocompatibility and high heating efficiency into a polymethyl methacrylate matrix to prepare magnetic bone cement, which minimized the affection for physicochemical properties and satisfied the hyperthermia requirement of the alternating magnetic field.

Spinel ferrite nanoparticles and nanocomposites for biomedical applications and their toxicity

This review focuses on the biomedical applications and toxicity of spinel ferrite nanoparticles (SFNPs) with more emphasis on the recently published work. A critical review is provided on recent advances of SFNPs applications in biomedical areas. The novelty of SFNPs in addressing the bottleneck problems encountered in the areas of health; in particular, for diagnosis and treatment of tumour cells are well reviewed. Furthermore, research gaps, toxicity of SFNPs and areas which still need more attention are highlighted. Based on the result of this review, the SFNPs have unlimited capacity in cancer treatment, disease diagnosis, magnetic resonance imaging, drug delivery and release. Overall, stepping out of the conventional way of treatment is difficult but also essential in bringing long lasting solution for cancer and other diseases treatment. In fact, the toxicity study and commercialisation of the SFNPs based cancer treatment options are the main challenges and need further study, in order to reduce unforeseen consequences.

Biocompatible coated magnetosome minerals with various organization and cellular interaction properties induce cytotoxicity towards RG-2 and GL-261 glioma cells in the presence of an alternating magnetic field

Background

Biologics magnetics nanoparticles, magnetosomes, attract attention because of their magnetic characteristics and potential applications. The aim of the present study was to develop and characterize novel magnetosomes, which were extracted from magnetotactic bacteria, purified to produce apyrogen magnetosome minerals, and then coated with Chitosan, Neridronate, or Polyethyleneimine. It yielded stable magnetosomes designated as M-Chi, M-Neri, and M-PEI, respectively. Nanoparticle biocompatibility was evaluated on mouse fibroblast cells (3T3), mouse glioblastoma cells (GL-261) and rat glioblastoma cells (RG-2). We also tested these nanoparticles for magnetic hyperthermia treatment of tumor in vitro on two tumor cell lines GL-261 and RG-2 under the application of an alternating magnetic field. Heating, efficacy and internalization properties were then evaluated.

Results

Nanoparticles coated with chitosan, polyethyleneimine and neridronate are apyrogen, biocompatible and stable in aqueous suspension. The presence of a thin coating in M-Chi and M-PEI favors an arrangement in chains of the magnetosomes, similar to that observed in magnetosomes directly extracted from magnetotactic bacteria, while the thick matrix embedding M-Neri leads to structures with an average thickness of 3.5 µm² per magnetosome mineral. In the presence of GL-261 cells and upon the application of an alternating magnetic field, M-PEI and M-Chi lead to the highest specific absorption rates of 120–125 W/g_Fe. Furthermore, while M-Chi lead to rather low rates of cellular internalization, M-PEI strongly associate to cells, a property modulated by the application of an alternating magnetic field.

Conclusions

Coating of purified magnetosome minerals can therefore be chosen to control the interactions of nanoparticles with cells, organization of the minerals, as well as heating and cytotoxicity properties, which are important parameters to be considered in the design of a magnetic hyperthermia treatment of tumor.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-017-0293-2) contains supplementary material, which is available to authorized users.

Biocompatible and stable magnetosome minerals coated with poly-l-lysine, citric acid, oleic acid, and carboxy-methyl-dextran for application in the magnetic hyperthermia treatment of tumors

Magnetic hyperthermia, in which magnetic nanoparticles are introduced into tumors and exposed to an alternating magnetic field (AMF), appears to be promising since it can lead to increased life expectancy in patients. Its efficacy can be further improved by using biocompatible iron oxide magnetosome minerals with better crystallinity and magnetic properties compared with chemically synthesized nanoparticles (IONP - Iron Oxide Nanoparticles). To fabricate such minerals, magnetosomes are first isolated from MSR-1 magnetotactic bacteria, purified to remove potentially toxic organic bacterial residues and stabilized with poly-l-lysine (N-PLL), citric acid (N-CA), oleic acid (N-OA), or carboxy-methyl-dextran (N-CMD). The different coated nanoparticles appear to be composed of a cubo-octahedral mineral core surrounded by a coating of different thickness, composition, and charge, and to be organized in chains of various lengths. The in vitro anti-tumor and heating efficacies of these nanoparticles were examined by bringing them into contact with GL-261 glioblastoma cells and by applying an AMF. This led to a specific absorption rate of 89-196 W g_Fe ^-1, measured using an AMF of 198 kHz and 34-47 mT, and to percentages of tumor cell destruction due to the exposure of the nanoparticles to the AMF of 10 ± 3% to 43 ± 3% depending on the coating agent. These results show the potential of this protocol for the tumor treatment by magnetic hyperthermia.

Sub-Micrometer Magnetic Nanocomposites: Insights into the Effect of Magnetic Nanoparticles Interactions on the Optimization of SAR and MRI Performance

There is increasing interest in the development of new magnetic polymeric carriers for biomedical applications such as trigger-controlled drug release, magnetic hyperthermia (MH) for the treatment of cancer, and as contrast agents in magnetic resonance imaging (MRI). This work describes the synthesis of sub-micrometer and magnetic polymer nanocomposite capsules (MPNCs) by combining in one single platform the biodegradable polymer poly-ε-caprolactone (PCL) and different concentrations of ∼8 nm oleic acid (OA)-functionalized magnetite nanoparticles (Fe₃O₄@OA), employing the oil-in-water emulsion/solvent evaporation method. The MPNCs showed a significant increase in particle size from ∼400 to ∼800 nm as the magnetic loading in the organic-inorganic hybrids increases from 1.0% to 10%. The MPNCs presented high incorporation efficiency of Fe₃O₄@OA nanoparticles, good colloidal stability, and super-paramagnetic properties. Interestingly, electron microscopy results showed that the Fe₃O₄@OA nanoparticles were preferentially located at the surface of the capsules. Evaluation of the magnetic properties showed that the saturation magnetization and the blocking temperature of the MPNCs samples increased as a function of the Fe₃O₄@OA loading. All the MPNCs exhibited heating when subjected to MH, and showed good specific absorption rates. Use of the formulations decreased the longitudinal (T₁) and transverse (T₂) relaxation times of water protons' nuclei, with excellent transverse relaxivity (r₂) values, especially in the case of the formulation with lowest Fe₃O₄@OA loading. Furthermore, the MPNCs-cell interaction was studied, and MPNCs showed lower cellular toxicity to normal cells compared to cancer cells. These findings help in understanding the relationships between magnetic nanoparticles and polymeric capsules, opening perspectives for their potential clinical uses as simultaneous heating sources and imaging probes in MH and MRI, respectively.