Toward the Separation of Different Heating Mechanisms in Magnetic Particle Hyperthermia

Evaluation of magnetic hyperthermia, drug delivery and biocompatibility (bone cell adhesion and zebrafish assays) of trace element co-doped hydroxyapatite combined with Mn-Zn ferrite for bone tissue applications

The treatment and regeneration of bone defects, especially tumor-induced defects, is an issue in clinical practice and remains a major challenge for bone substitute material invention. In this research, a composite material of biomimetic bone-like apatite based on trace element co-doped apatite (Ca10-δ M δ (PO4)5.5(CO3)0.5(OH)2; M = trace elements of Mg, Fe, Zn, Mn, Cu, Ni, Mo, Sr and BO3 3-; THA)-integrated-biocompatible magnetic Mn-Zn ferrite ((Mn, Zn)Fe2O4 nanoparticles, BioMags) called THAiBioMags was prepared via a co-precipitation method. Its characteristics, i.e., physical properties, hyperthermia performance, ion/drug delivery, were investigated in vitro using osteoblasts (bone-forming cells) and in vivo using zebrafish. The synthesized THAiBioMags particles revealed superparamagnetic behaviour at room temperature. Under the influence of an alternating magnetic field, THAiBioMags particles demonstrated a change in temperature, indicating their potential for magnetic hyperthermia, in which THAiBioMags further exhibited a specific absorption rate (SAR) value of 9.44 W g-1 (I = 44 A, H = 6.03 kA m-1 and f = 130 kHz). In addition, the as-prepared particles demonstrated sustained ion/drug (doxorubicin (DOX)) release under physiological pH conditions. Biological assay analysis revealed that THAiBioMags exhibited no toxicity towards osteoblast cells and demonstrated excellent cell adhesion properties. In vivo studies employing an embryonic zebrafish model showed the non-toxic nature of the synthesized THAiBioMags particles, as revealed by evaluation of the survivability, hatching rate, and embryonic morphology. These results could potentially lead to the design and fabrication of magnetic scaffolds to be used in therapeutic treatment and bone regeneration.

Cytotoxic evaluation of pure and doped iron oxide nanoparticles on cancer cells: a magnetic fluid hyperthermia perspective

The need of the hour with respect to cancer treatment is a targeted approach with minimal or nil ramifications. Apropos, magnetic fluid hyperthermia (MFH) is emerging as a potential therapeutic strategy with anticipated reduced side effects for solid tumors. MFH causes cytotoxicity due to the heat generated owing to Hysteresis, Neel, and Brownian relaxation losses once magnetic nanoparticles (MNPs) carrying cancer cells are placed under an alternating magnetic field. With respect to MFH, iron oxide-based MNPs have been most extensively studied to date compared to other metal oxides with magnetic properties. The effectiveness of MFH relies on the composition, coating, size, physical and biocompatible properties of the MNPs. Pure iron oxide and doped iron oxide MNPs have been utilized to study their effects on cancer cell killing through MFH. This review evaluates the biocompatibility of pure and doped iron oxide MNPs and their subsequent hyperthermic effect for effectively killing cancer cells in vitro and in vivo.

Flame spray pyrolyzed carbon-encapsulated Au/Fe3O4 nanoaggregates enabled efficient photothermal therapy and magnetic hyperthermia of esophageal cancer cells

Multifunctional magneto-plasmonic nanoparticles with magnetic hyperthermia and photothermal therapy could kill cancer cells efficiently. Herein, carbon-encapsulated Au/Fe3O4 (Au/Fe3O4@C) was fabricated using an enclosed flame spray pyrolysis. The nanostructures, including an Fe3O4 core (51.9-55.2 nm) with a decreasing carbon shell thickness and an Au core (4.68-8.75 nm) coated with 2-4 graphite layers, were tailored by tuning the C2H4 content in the reacting gas mixture. Saturation magnetization (33.7-48.2 emu/g) and optical absorption were determined. The carbon shell facilitated the dispersion of Au/Fe3O4 and restrained their laser-induced and magnetic field-induced coalescence and growth. Au/Fe3O4@C exhibited excellent magnetic resonance imaging capability (91.4 mM-1 s-1) and photothermal performance (65.4°C for 0.8 mg/mL Au/Fe3O4@C at a power density of 1.0 W/cm2 after 300 s near-IR laser irradiation (808 nm)). Moreover, the combined application of photothermal and magnetic-heating properties reduced the required intensity of both laser and magnetic field compared to the intensity of separate situations. Our work provides a unique, intriguing approach to preparing multicomponent core/shell nanoaggregates that are promising candidates for esophageal cancer cell therapy.

Study of biopolymer encapsulated Eu doped Fe3O4 nanoparticles for magnetic hyperthermia application

An exciting prospect in the field of magnetic fluid hyperthermia (MFH) has been the integration of noble rare earth elements (Eu) with biopolymers (chitosan/dextran) that have optimum structures to tune specific effects on magnetic nanoparticles (NPs). However, the heating efficiency of MNPs is primarily influenced by their magnetization, size distribution, magnetic anisotropy, dipolar interaction, amplitude, and frequency of the applied field, the MNPs with high heating efficiency are still challenging. In this study, a comprehensive experimental analysis has been conducted on single-domain magnetic nanoparticles (SDMNPs) for evaluating effective anisotropy, assessing the impact of particle-intrinsic factors and experimental conditions on self-heating efficiency in both noninteracting and interacting systems, with a particular focus on the dipolar interaction effect. The study successfully reconciles conflicting findings on the interaction effects in the agglomeration and less agglomerated arrangements for MFH applications. The results suggest that effective control of dipolar interactions can be achieved by encapsulating Chitosan/Dextran in the synthesized MNPs. The lower dipolar interactions successfully tune the self-heating efficiency and hold promise as potential candidates for MFH applications.

A comprehensive scrutiny to controlled dipolar interactions to intensify the self-heating efficiency of biopolymer encapsulated Tb doped magnetite nanoparticles

An exciting prospect in the field of magnetic fluid hyperthermia (MFH) has been the integration of noble rare earth elements with biopolymers (chitosan/dextran) that have optimum structures to tune specific effects on magnetic nanoparticles (MNPs). Remarkably, it has been demonstrated that dipole-dipole interactions have a significant influence on nanoparticle dynamics. In this article, we present an exhaustive scrutiny of dipolar interactions and how this affects the efficiency of MFH applications. In particular, we prepare chitosan and dextran-coated Tb-doped MNPs and study whether it is possible to increase the heat released by controlling the dipole-dipole interactions. It has been indicated that even moderate control of agglomeration may substantially impact the structure and magnetization dynamics of the system. Besides estimating the specific loss power value, our findings provide a deep insight into the relaxation mechanisms and bring to light how to tune the self-heating efficacy towards magnetic hyperthermia.

Control of physical properties in BiFeO3nanoparticles via Sm3+and Co2+ion doping

Highly crystalline BiFeO3(BFO), Bi0.97Sm0.03FeO3(Sm-BFO) and BiFe0.97Co0.03O3(Co-BFO) nanoparticles (NPs) were utilized as potential magnetic hyperthermia agents at two different frequencies in the radiofrequency (RF) range, and the effect of Sm3+and Co2+ion doping on the physical properties of the material was examined. The thermal behaviour of the as-prepared powders disclosed that the crystallization temperature of the powders is affected by the incorporation of the dopants into the BFO lattice and the Curie transition temperature is decreased upon doping. Vibrational analysis confirmed the formation of the R3c phase in all compounds through the characteristic FT-IR absorbance bands assigned to O-Fe-O bending vibration and Fe-O stretching of the octahedral FeO6group in the perovskite, as well as through Raman spectroscopy. The shift of the Raman-active phonon modes in Sm-BFO and Co-BFO NPs indicated structural distortion of the BFO lattice, which resulted in increased local polarization and enhanced visible light absorption. The aqueous dispersion of Co-BFO NPs showed the highest magnetic hyperthermia performance at 30 mT/765 kHz, entering the therapeutic temperature window for cancer treatment, whereas the heating efficiency of all samples was increased with increasing frequency from 375 to 765 kHz, making our doped nanoparticles to be suitable candidates for potential biomedical applications.

Laser-Ablative Synthesis of Silicon-Iron Composite Nanoparticles for Theranostic Applications

The combination of photothermal and magnetic functionalities in one biocompatible nanoformulation forms an attractive basis for developing multifunctional agents for biomedical theranostics. Here, we report the fabrication of silicon-iron (Si-Fe) composite nanoparticles (NPs) for theranostic applications by using a method of femtosecond laser ablation in acetone from a mixed target combining silicon and iron. The NPs were then transferred to water for subsequent biological use. From structural analyses, it was shown that the formed Si-Fe NPs have a spherical shape and sizes ranging from 5 to 150 nm, with the presence of two characteristic maxima around 20 nm and 90 nm in the size distribution. They are mostly composed of silicon with the presence of a significant iron silicide content and iron oxide inclusions. Our studies also show that the NPs exhibit magnetic properties due to the presence of iron ions in their composition, which makes the formation of contrast in magnetic resonance imaging (MRI) possible, as it is verified by magnetic resonance relaxometry at the proton resonance frequency. In addition, the Si-Fe NPs are characterized by strong optical absorption in the window of relative transparency of bio-tissue (650-950 nm). Benefiting from such absorption, the Si-Fe NPs provide strong photoheating in their aqueous suspensions under continuous wave laser excitation at 808 nm. The NP-induced photoheating is described by a photothermal conversion efficiency of 33-42%, which is approximately 3.0-3.3 times larger than that for pure laser-synthesized Si NPs, and it is explained by the presence of iron silicide in the NP composition. Combining the strong photothermal effect and MRI functionality, the synthesized Si-Fe NPs promise a major advancement of modalities for cancer theranostics, including MRI-guided photothermal therapy and surgery.