Improvement of Hyperthermia Properties of Iron Oxide Nanoparticles by Surface Coating

Magnetically Induced Catalysis: Definition, Advances, and Potential

The rapidly growing importance of electrification in the chemical industry opens room for disruptive innovations regarding energy input into catalytic processes. Energy efficiency and dynamics of renewable energy supplies represent important challenges, but the design of catalytic systems to cope with such new frameworks may also stimulate the discovery of new catalyst materials and reaction pathways. In this context, many opportunities arise when catalysts are activated in a rapid, localized, and energy-efficient manner. Among the various concepts to achieve adaptivity in catalysis, magnetic induction heating applied directly at the catalyst or in vicinity of the active site has gained increasing attention recently. In this Scientific Perspective, we provide a coherent framework to the emerging field of catalysis using magnetic fields-and in particular alternating current magnetic fields-to activate catalytic materials and define it as magnetically induced catalysis. Promising approaches and selected examples are described to illustrate the scientific concept and to highlight its broad potential for innovation in catalysis from laboratory to industrial scale.

Enhanced photocatalytic degradation of malachite green and trypan blue using 3-aminopropyl triethoxysilane (APTES) functionalized iron oxide nanocomposite

Biochar-capped iron oxide nanoparticle functionalized with 3-aminopropyl triethoxysilane (APTES) was synthesized and used as photocatalysts for the degradation of malachite green (MG) and trypan blue (TPB) dyes. Powder X-ray diffraction patterns confirmed the crystalline cubic spinel structure of Fe3O4. HRTEM image shows nanocomposites with an average particle size of 22.4 nm, interplanar spacings of 0.297 nm and 0.245 nm, which correspond to the (220) and (222) planes of Fe3O4. SAED patterns indicate that Fe3O4@BC/APTES nanocomposite is polycrystalline. The energy bandgap of the biochar-capped iron oxide nanoparticles was reduced from 3.47 to 2.85 eV after functionalization with APTES. Photocatalytic degradation potential of the nanocomposite was evaluated with malachite green (MG) and trypan blue (TPB) dyes using the response surface methodology based on the Box-Behnken design (RSM-BDD). The optimal degradation efficiency from RSM-BBD for MG was 99.94% with a catalyst dosage of 7.5 mg, dye concentration of 50 ppm, and pH of 9 for 105 min. The optimum parameters for TPB were found to be a concentration of 30 ppm, a catalyst dosage of 12 mg, a pH of 5, and 85.77% of degradation after 90 min. Reusability studies show that the nanocomposite can be reused five times without significant reduction in the photocatalytic degradation efficiency.

Investigation on the heating effects of intra-tumoral injectable magnetic hydrogels (IT-MG) for cancer hyperthermia

Capacitive-based radiofrequency (Rf) radiation at 27 MHz offers a non-invasive approach for inducing hyperthermia, making it a promising technique for thermal cancer therapy applications. To achieve focused and site-specific hyperthermia, Rf-responsive materials is required to convert Rf radiation into localized heat efficiently. Nanoparticles capable of absorbing Rf energy and convert into heat for targeted ablation are of critical importance. In this study, we developed and evaluated an Intra-tumoral injectable magnetic hydrogel (IT-MG) composed of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) impregnated in low molecular weight Hyaluronic Acid (HA) forming HA-SPIONs. Our systematic investigation revealed that HA-SPIONs exposed to Rf radiation significantly increased temperature, reaching up to 50 °C. Further testing in tissue-mimicking phantom models also showed consistent heating, with temperatures stabilizing at 43 °C, ideal for localized hyperthermia. The ability of HA-SPIONs to act as an effective localized heating agent when exposed to 27 MHz Rf radiation, reaching apoptosis-inducing temperature, has not been previously reported. In conclusion, synergistic effects of IT-MG in bothin-vitroand tumor-mimicking phantom models demonstrate improved and localized hyperthermia, facilitating adjuvant cancer treatment.

Liver-targeting iron oxide nanoparticles and their complexes with plant extracts for biocompatibility

Thanks to their simple synthesis, controlled physical properties, and minimal toxicity, iron oxide nanoparticles (Fe3O4 NPs) are widely used in many biomedical applications (e.g., bioimaging, drug delivery, biosensors, diagnostics, and theranostics). However, the use of NPs does not preclude the possibility of selective toxicity and undesirable effects, including accumulation in tissues and direct interaction with specific biological targets. This study evaluated the biocompatibility of Fe3O4 NPs, Teucrium polium (T. polium) extract, rutin, and the corresponding complexes on the liver tissue of healthy white Wistar rats. The impact profile of the synthesized Fe3O4 NPs (15 ± 4 nm), rutin, T. polium extract, and their complexes on biochemical markers of liver function (ALT, AST, ALP, GGT, HDL, LDL, total cholesterol, total protein, and albumin) and morphological indicators of rat liver was investigated. Fe3O4 NPs, rutin, and T. polium extract do not show direct hepatotoxicity when administered intraperitoneally to rats, unlike their complexes. All agents exert a hypolipidemic effect by lowering LDL, despite maintaining the synthetic functions of the liver. Fe3O4 NPs increase the activity of GPO, which is associated with their peroxidase-like properties. A multifaceted and diverse mechanism of action of all studied samples on the liver of Wistar rats was identified.

Green Sol-Gel Synthesis of Iron Oxide Nanoparticles for Magnetic Hyperthermia Applications

BACKGROUND/OBJECTIVES

The unique properties of iron oxide nanoparticles have attracted significant interest within the biomedical community, particularly for magnetic hyperthermia applications. Various synthesis methods have been developed to optimize these nanoparticles.

METHODS

In this study, we employed a powdered coconut water (PCW)-assisted sol-gel method to produce magnetite nanoparticles for the first time. A comprehensive analysis of the thermal (differential thermal analysis and thermogravimetry), structural (X-ray diffraction), morphological (scanning electron microscopy with energy dispersive spectroscopy), magnetic (vibrating sample magnetometer and hyperthermia), and biological (cytotoxicity essays) properties was conducted to assess their potential for magnetic hyperthermia.

RESULTS

Samples heat-treated at 700 °C and 400 °C (washed powder) for 4 h under argon presented only magnetite in their composition. The micrometer-sized particles exhibited ferrimagnetic behavior, with saturation magnetization values of 37, 76, and 10 emu/g and specific absorption rates (SAR) of 27.1, 19.9, and 14.1 W/g, respectively, for treatments at 350 °C (48 h), 700 °C (4 h), and 400 °C (washed powder, 4 h) under an argon atmosphere. Biological tests showed no cytotoxicity below 10 mg/mL.

CONCLUSIONS

The findings highlight the potential of PCW-assisted synthesis as a sustainable and efficient strategy for producing pure magnetite, with powder washing preceding the heat treatment enabling the attainment of this phase at lower temperatures. Nevertheless, the micrometer-scale dimensions is observed in the morphological analysis limit their suitability for biomedical applications.

Adrenocortical Cancer Cell uptake of Iron Oxide Nanoparticles

Adrenocortical carcinoma (ACC) is a rare cancer with poor prognosis, treated primarily through surgery and chemotherapy. Other treatments like radiation or thermal ablation for metastases have limited success, and recurrence is common. More effective management options are needed. Magnetic iron oxide nanoparticles (IONP) show promise in cancer treatment due to their ability to be modified for selective uptake by cancer cells. This study investigated IONP uptake in ACC cell lines (H295R, HAC-15, MUC-1) using a multicellular model with endothelial cells (HUVEC) and monocytes. IONP uptake was concentration- and time-dependent, with optimal uptake at 10 μg/mL. IONP were found in the cytoplasm and intracellular vesicles of ACC cells. However, endothelial cells and monocytes also absorbed IONP, reducing uptake by ACC cells. These findings suggest ACC cells actively take up IONP, but better targeting is needed to enhance uptake specificity and efficiency.

Recent advancements and clinical aspects of engineered iron oxide nanoplatforms for magnetic hyperthermia-induced cancer therapy

The pervasiveness of cancer is a global health concern posing a major threat in terms of mortality and incidence rates. Magnetic hyperthermia (MHT) employing biocompatible magnetic nanoparticles (MNPs) ensuring selective attachment to target sites, better colloidal stability and conserving nearby healthy tissues has garnered widespread acceptance as a promising clinical treatment for cancer cell death. In this direction, multifunctional iron oxide nanoparticles (IONPs) are of significant interest for improved cancer care due to finite size effect associated with inherent magnetic properties. This review offers a comprehensive perception of IONPs-mediated MHT from fundamentals to clinical translation, by elucidating the underlying mechanism of heat generation and the related influential factors. Biological mechanisms underlying MHT-mediated cancer cell death such as reactive oxygen species generation and lysosomal membrane permeabilization have been discussed in this review. Recent advances in biological interactions (in vitro and in vivo) of IONPs and their translation to clinical MHT applications are briefed. New frontiers and prospects of promising combination cancer therapies such as MHT with photothermal therapy, cancer starvation therapy and sonodynamic therapy are presented in detail. Finally, this review concludes by addressing current crucial challenges and proposing possible solutions to achieve clinical success.

Light-Controlled Magnetic Properties: An Energy-Efficient Opto-Mechanical Control over Magnetic Films by Liquid Crystalline Networks

Magnetostrictive materials are essential components in sensors, actuators, and energy-storage devices due to their ability to convert mechanical stress into changes in magnetic properties and vice-versa. However, their operation typically requires physical contact to apply stress or relies on magnetic field sources to control magnetic properties. This poses significant limitations to devices miniaturization and their integration into contactless technologies. This work reports on an approach that overcomes these limitations by using light to transfer mechanical stress to a magnetostrictive device, thereby achieving non-contact and reversible opto-mechanical control of its magnetic and electrical properties. The proposed solution combines a magnetostrictive Fe70Ga30 thin film with a photo-responsive Liquid Crystalline Network (LCN). Magnetic properties are modulated by changing the light wavelength and illumination time. Remarkably, the stable shape change of the LCN induced by ultraviolet (UV) light leads to the retention of magnetic properties even after the light is switched off, resulting in a magnetic memory effect with an energy consumption advantage over the use of conventional magnetic field applicators. The memory effect is erased by visible light, which releases the mechanical stress in the photoresponsive layer. Therefore, this new composite material creates a fully reconfigurable magnetic system controlled by light.

Recent progress and current status of surface engineered magnetic nanostructures in cancer theranostics

Cancer theranostic is the combination of diagnosis and therapeutic modalities for cancer treatment. It realizes a more flexible, precise and non-invasive treatment of patients. In this aspect, magnetic nanostructures (MNSs) have gained paramount importance and revolutionized the cancer management due to their unique physicochemical properties and inherent magnetic characteristics. MNSs have amazing theranostic ability starting from drug delivery to magnetic hyperthermia and magnetic resonance imaging to multimodal imaging in association with radioisotopes or fluorescent probes. Precise regulation over the synthetic process and their consequent surface functionalization makes them even more fascinating. The ultimate goal is to develop a platform that combines multiple diagnostic and therapeutic functionalities based on MNSs. This perspective has provided an overview of the state-of-art of theranostic applications of MNSs. Special emphasis has been dedicated towards the importance of synthetic approaches of MNSs as well as their subsequent surface engineering and integration with biological/therapeutic molecules that decide the final outcomes of the efficacy of MNSs in theranostic applications. Moreover, the recent advancements, opportunities and allied challenges towards clinical applications of MNSs in cancer management have been demonstrated.

Isolation of B Cells Using Silane-Coated Magnetic Nanoparticles

One of the most important advantages and applications of coated nanoparticles in biological applications is their use in isolating different types of cells to diagnose and treat all types of diseases. Therefore, in this research work, the possibility of isolation and enrichment of B cells using magnetic iron oxide nanoparticles have been investigated. In this regard, magnetic nanoparticles are first coated with (3-aminopropyl)triethoxysilane to make them hydrophilic and prevent their clumping, then reacted with and rendered biocompatible by FITC anti-human CD20 antibody. These nanoparticles containing antibodies have been used to isolate B cells from the lymphatic cells. Transmission electron microscopy (TEM) and vibrating-sample magnetometry (VSM) tests were used to check the magnetic properties and coating of nanoparticles. The flow cytometry and fluorescent microscopy tests are used to check antibody binding to nanoparticles. Moreover, flow cytometry tests were used to check the extent of cell separation. Results show that nanoparticles reacted with 450 μL of antibody (T450) performed better than other nanoparticles in isolating B cells.

Elaboration of Functionalized Iron Oxide Nanoparticles by Microwave-Assisted Co-Precipitation: A New One-Step Method in Water

Iron oxide nanoparticles are extensively utilized in various fields, particularly in biomedical applications. For such uses, nanoparticles must meet specific criteria, including precise size, morphology, physico-chemical properties, stability, and biocompatibility. Microwave-assisted co-precipitation offers an efficient method for producing water-soluble nanoparticles. Functionalization with citrate during synthesis is crucial for achieving a stable colloidal solution. This study aims to compare the effectiveness of conventional co-precipitation with microwave-assisted co-precipitation. The synthesized nanoparticles were characterized using TEM, DLS, FTIR, XRD, and magnetic measurements. The findings indicate that the in situ citrate functionalization during synthesis results in stable, non-aggregated nanoparticles.

Heating Induced Nanoparticle Migration and Enhanced Delivery in Tumor Treatment Using Nanotechnology

Nanoparticles have been developed as imaging contrast agents, heat absorbers to confine energy into targeted tumors, and drug carriers in advanced cancer treatment. It is crucial to achieve a minimal concentration of drug-carrying nanostructures or to induce an optimized nanoparticle distribution in tumors. This review is focused on understanding how local or whole-body heating alters transport properties in tumors, therefore leading to enhanced nanoparticle delivery or optimized nanoparticle distributions in tumors. First, an overview of cancer treatment and the development of nanotechnology in cancer therapy is introduced. Second, the importance of particle distribution in one of the hyperthermia approaches using nanoparticles in damaging tumors is discussed. How intensive heating during nanoparticle hyperthermia alters interstitial space structure to induce nanoparticle migration in tumors is evaluated. The next section reviews major obstacles in the systemic delivery of therapeutic agents to targeted tumors due to unique features of tumor microenvironments. Experimental observations on how mild local or whole-body heating boosts systemic nanoparticle delivery to tumors are presented, and possible physiological mechanisms are explored. The end of this review provides the current challenges facing clinicians and researchers in designing effective and safe heating strategies to maximize the delivery of therapeutic agents to tumors.

Alternating magnetic field guiding system for MNP hyperthermia treatment of deep-seated cancers

OBJECTIVES

Demonstrate the potential application of a novel, endoscope-like device to guide and focus an alternating magnetic field (AMF) for treating deep-seated cancers via magnetic nanoparticle hyperthermia (MNPH).

METHODS

AMF delivery, MNP activation, and eddy current distribution characteristics are investigated through experimental studies in phantoms and computational simulations using a full 3-dimensional human model. The 3D simulations compare the novel device to traditional AMF designs, including a MagForce-like, two-coil system (used clinically) and a single surface-coil system.

RESULTS

The results demonstrate that this approach can deliver the same magnetic field strength at the prostate's centroid as traditional AMF designs, while reducing eddy current heating by 2 to 6 times. At the same level of normal tissue heating, this method provides 5.0 times, 1.5 times, and 0.92 times the magnetic field strength to the nearest, centroid, and farthest regions of the prostate, respectively.

CONCLUSIONS

These results demonstrate proof-of-concept for an endoscopic magnetic field guiding and focusing system capable of delivering clinically relevant AMF from a distance. This innovative approach offers a promising alternative to conventional field delivery methods by directing AMF through the body, concentrating it in the tumor region, reducing eddy currents in surrounding healthy tissue, and avoiding exposure of nearby metallic implants.

Piezoelectric Behaviour in Biodegradable Carrageenan and Iron (III) Oxide Based Sensor

This paper is dedicated to the research of phenomena noticed during tests of biodegradable carrageenan-based force and pressure sensors. Peculiar voltage characteristics were noticed during the impact tests. Therefore, the sensors' responses to impact were researched more thoroughly, defining time-dependent sensor output signals from calibrated energy impact. The research was performed using experimental methods when a free-falling steel ball impacted the sensor material to create relatively definable impact energy. The sensor's output signal, which is analogue voltage, was registered using an oscilloscope and transmitted to the PC for further analysis. The obtained results showed a very interesting outcome, where the sensor, which was intended to be piezoresistive, demonstrated a combination of behaviour typical for galvanic cells and piezoelectric material. It provides a stable DC output that is sensitive to the applied statical pressure, and in case of a sudden impact, like a hit, it demonstrates piezoelectric behaviour with some particular effects, which are described in the paper as proton transfer in the sensor-sensitive material. Such phenomena and sensor design are a matter of further development and research.

Increased endocytosis rate and enhanced lysosomal pathway of silica-coated superparamagnetic nanoparticles into M-HeLa cells compared with cultured primary motor neurons

The unique properties of superparamagnetic iron oxide nanoparticles (SPIONs) enable their use as magnetic biosensors, targeted drug delivery, magnetothermia, magnetic resonance imaging, etc. Today, SPIONs are the only type of metal oxide nanoparticles approved for biomedical application. In this work, we analyzed the cellular response to the previously reported luminescent silica coated SPIONs of the two cell types: M-HeLa cells and primary motor neuron culture. Both internalization pathways and intracellular fate of SPIONs have been compared for these cell lines using fluorescence and transmission electron microscopy. We also applied a pharmacological approach to analyze the endocytosis pathways of SPIONs into the investigated cell lines. The penetration of SPIONs into M-HeLa cells is already noticeable within 30 s of incubation through both caveolin-dependent endocytosis and micropinocytosis. However, incubation for a longer time (1 h at least) is required for the internalization of SPIONs into motor neuron culture cells provided by dynamin-dependent endocytosis and macropinocytosis. The intracellular colocalization assay reveals that the lysosomal internalization pathway of SPIONs is also dependent on the cell type. The lysosomal pathway is much more pronounced for M-HeLa cells compared with motor neurons. The emphasized differences in cellular responses of the two cell lines open up new opportunities in the application of SPIONs in the diagnostics and therapy of cancer cells.

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.

Application of Nanoparticles for Magnetic Hyperthermia for Cancer Treatment-The Current State of Knowledge

Hyperthermia (HT) is an anti-cancer therapy commonly used with radio and chemotherapies based on applying heat (39-45 °C) to inhibit tumor growth. However, controlling heat towards tumors and not normal tissues is challenging. Therefore, nanoparticles (NPs) are used in HT to apply heat only to tumor tissues to induce DNA damage and the expression of heat shock proteins, which eventually result in apoptosis. The aim of this review article is to summarize recent advancements in HT with the use of magnetic NPs to locally increase temperature and promote cell death. In addition, the recent development of nanocarriers as NP-based drug delivery systems is discussed. Finally, the efficacy of HT combined with chemotherapy, radiotherapy, gene therapy, photothermal therapy, and immunotherapy is explored.

Biosynthesis, characterization, magnetic hyperthermia, and in vitro toxicity evaluation of quercetin-loaded magnetoliposome lipid bilayer hybrid system on MCF-7 breast cancer

Novel biocompatible and effective hyperthermia (HT) treatment materials for breast cancer therapeutic have recently attracting researchers, because of their effective ablation of cancer cells and negligible damage to healthy cells. Magnetoliposome (MLs) have numerous possibilities for utilize in cancer treatment, including smart drug delivery (SDD) mediated through alternating magnetic fields (AMF). In this work, magnesium ferrite (MgFe2O4) encapsulated with liposomes lipid bilayer (MLs), Quercetin (Q)-loaded MgFe2O4@Liposomes (Q-MLs) nano-hybrid system were successfully synthesized for magnetic hyperthermia (MHT) and SDD applications. The hybrid system was well-investigated by different techniques using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), Energy dispersive X-ray (EDX), Vibrating sample magnetometer (VSM), Transmission electron microscope (TEM), and Zeta Potential (ZP). The characterization results confirmed the improving quercetin-loading on the MLs surface. TEM analysis indicated the synthesized MgFe2O4, MLs, and Q-MLs were spherical with an average size of 23.7, 35.5, and 329.5 nm, respectively. The VSM results revealed that the MgFe2O4 exhibit excellent and effective saturation magnetization (MS) (40.5 emu/g). Quercetin drug loading and entrapment efficiency were found to be equal to 2.1 ± 0.1% and 42.3 ± 2.2%, respectively. The in-vitro Q release from Q-loaded MLs was found 40.2% at pH 5.1 and 69.87% at pH 7.4, verifying the Q-loading pH sensitivity. The MLs and Q-MLs hybrid system as MHT agents exhibit specific absorption rate (SAR) values of 197 and 205 W/g, correspondingly. Furthermore, the Q-MLs cytotoxicity was studied on the MCF-7 breast cancer cell line, and the obtained data demonstrated that the Q-MLs have a high cytotoxicity effect compared to MLs and free Q.

A nudge over the relaxation plateau: effect of pH, particle concentration, and medium viscosity on the AC induction heating efficiency of biocompatible chitosan-coated Fe3O4nanoparticles

The effects of pH, MNP concentration, and medium viscosity on the magnetic fluid hyperthermia (MFH) properties of chitosan-coated superparamagnetic Fe3O4nanoparticles (MNPs) are probed here. Due to the protonation of the amide groups, the MNPs are colloidally stable at lower pH (∼2), but form aggregates at higher pH (∼8). The increased aggregate size at higher pH causes the Brownian relaxation time (τB) to increase, leading to a decrease in specific absorption rate (SAR). For colloidal conditions ensuring Brownian-dominated relaxation dynamics, an increase in MNP concentrations or medium viscosity is found to increase theτB. SAR decreases with increasing MNP concentration, whereas it exhibits a non-monotonic variation with increasing medium viscosity. Dynamic hysteresis loop-based calculations are found to be in agreement with the experimental results. The findings provide a greater understanding of the variation of SAR with the colloidal properties and show the importance of relaxation dynamics on MFH efficiency, where variations in the frequency-relaxation time product across the relaxation plateau cause significant variations in SAR. Further, thein vitrocytotoxicity studies show good bio-compatibility of the chitosan-coated Fe3O4MNPs. Higher SAR at acidic pH for bio-medically acceptable field parameters makes the bio-compatible chitosan-coated Fe3O4MNPs suitable for MFH applications.

Dual-responsive magnetic nanodroplets for controlled oxygen release via ultrasound and magnetic stimulation

Magnetic oxygen-loaded nanodroplets (MOLNDs) are a promising class of nanomaterials dually sensitive to ultrasound and magnetic fields, which can be employed as nanovectors for drug delivery applications, particularly in the field of hypoxic tissue treatment. Previous investigations were primarily focused on the application of these hybrid systems for hyperthermia treatment, exploiting magnetic nanoparticles for heat generation and nanodroplets as carriers and ultrasound contrast agents for treatment progress monitoring. This work places its emphasis on the prospect of obtaining an oxygen delivery system that can be activated by both ultrasound and magnetic fields. To achieve this goal, Fe3O4 nanoparticles were employed to decorate and induce the magnetic vaporization of OLNDs, allowing oxygen release. We present an optimized method for preparing MOLNDs by decorating nanodroplets made of diverse fluorocarbon cores and polymeric coatings. Furthermore, we performed a series of characterizations for better understanding how magnetic decoration can influence the physicochemical properties of OLNDs. Our comprehensive analysis demonstrates the efficacy of magnetic stimulation in promoting oxygen release compared to conventional ultrasound-based methods. We emphasize the critical role of selecting the appropriate fluorocarbon core and polymeric coating to optimize the decoration process and enhance the oxygen release performance of MOLNDs.

Preparation of stable colloidal dispersion of surface modified Fe3O4 nanoparticles for magnetic heating applications

The effect of surface modification on enhancing the magnetic heating behavior of magnetic nano fluids were investigated, for this purpose Fe3O4 nanoparticles were synthesized using co-precipitation method and surface modification was done using citric acid, ascorbic acid, tetraethyl orthosilicate (TEOS), polyvinyl alcohol (PVA) and polyethylene glycol (PEG). Experimental heating tests using AC magnetic field were done in the frequency of 100 kHz and different magnetic field (H) intensities. Theoretically the specific absorption rate (SAR) in magnetic nano fluids is independent of nanoparticles concentration but the experimental results showed different behavior. The theoretical SAR value @ H = 12kA.m-1 for Nano fluids containing bare Fe3O4 nanoparticles was 11.5 W/g but in experimental tests the obtained value was 9.72 W/g for nano fluid containing 20,000 ppm of dispersed nanoparticles. The experimental SAR calculation was repeated for sample containing 10,000 ppm of nanoparticles and the results showed increase in experimental SAR that is an evidence of nanoparticles agglomeration in higher concentrations. The surface modification has improved the dispersion ability of the nanoparticles. The Ratio of SAR, experimental, 20000ppm to SAR, experimental, 10000ppm was 0.85 for bare Fe3O4 nanoparticles dispersion but in case of surface modified nanoparticles this ratio has increased up to 0.98 that shows lower agglomeration of nanoparticles as a result of surface modification, although on the other hand the surface modification agents were magnetically passive and so it is expected that in constant concentration the SAR for bare Fe3O4 nanoparticles to be higher than this variable for surface modified nanoparticles. At lower concentrations the dispersions containing bare Fe3O4 nanoparticles showed higher SAR values but at higher concentrations the surface modified Fe3O4 nanoparticles showed better results although the active agent amount was lower at them. Finally, it should be noted that the nanoparticles that were surface modified using polymeric agents showed the highest decrease in experimental SAR amounts comparing theoretical results that was because of the large molecules of polymers comparing other implemented surface modification agents.

Magnetic hybrid Pd/Fe-oxide nanoparticles meet the demands for ablative thermo-brachytherapy

OBJECTIVE

To investigate the potential of hybrid Pd/Fe-oxide magnetic nanoparticles designed for thermo-brachytherapy of breast cancer, considering their specific loss power (SLP) and clinical constraints in the applied magnetic field.

METHODS

Hybrid nanoparticles consisting of palladium-core and iron oxide shell of increasing thickness, were suspended in water and their SLPs were measured at varying magnetic fields (12-26 mT peak) and frequencies (50-730 kHz) with a commercial alternating magnetic field generator (magneTherm™ Digital, nanoTherics Ltd.).

RESULTS

Validation of the heating device used in this study with commercial HyperMag-C nanoparticles showed a small deviation (±4%) over a period of 1 year, confirming the reliability of the method. The integration of dual thermometers, one in the center and one at the bottom of the sample vial, allowed monitoring of homogeneity of the sample suspensions. SLPs measurements on a series of nanoparticles of increasing sizes showed the highest heating for the diameter of 21 nm (SLP = 225 W/g) at the applied frequencies of 346 and 730 kHz. No heating was observed for the nanoparticles with the size <14 nm, confirming the importance of the size-parameter. The heating ability of the best performing Pd/Fe-oxide-21 was calculated to be sufficient to ablate tumors with a radius ±4 and 12 mm using 10 and 1 mg/mL nanoparticle concentration, respectively.

CONCLUSIONS

Nanoparticles consisting of non-magnetic palladium-core and magnetic iron oxide shell are suitable for magnetic hyperthermia/thermal ablation under clinically safe conditions of 346 kHz and 19.1 mT, with minimal eddy current effects in combination with maximum SLP.

Recent advances in zinc ferrite (ZnFe2O4) based nanostructures for magnetic hyperthermia applications

Spinel ferrite-based magnetic nanomaterials have been investigated for numerous biomedical applications, including targeted drug delivery, magnetic hyperthermia therapy (MHT), magnetic resonance imaging (MRI), and biosensors, among others. Recent studies have found that zinc ferrite-based nanomaterials are favorable candidates for cancer theranostics, particularly for magnetic hyperthermia applications. Zinc ferrite exhibits excellent biocompatibility, minimal toxicity, and more importantly, exciting magnetic properties. In addition, these materials demonstrate a Curie temperature much lower than other transition metal ferrites. By regulating synthesis protocols and/or introducing suitable dopants, the Curie temperature of zinc ferrite-based nanosystems can be tailored to the MHT therapeutic window, i.e., 43-46 °C, a range which is highly beneficial for clinical hyperthermia applications. Furthermore, zinc ferrite-based nanostructures have been extensively used in successful pre-clinical trials on mice models focusing on the synergistic killing of cancer cells involving magnetic hyperthermia and chemotherapy. This review provides a systematic and comprehensive understanding of the recent developments of zinc ferrite-based nanomaterials, including doped particles, shape-modified structures, and composites for magnetic hyperthermia applications. In addition, future research prospects involving pure ZnFe2O4 and its derivative nanostructures have also been proposed.

A Review of the Current State of Magnetic Force Microscopy to Unravel the Magnetic Properties of Nanomaterials Applied in Biological Systems and Future Directions for Quantum Technologies

Magnetism plays a pivotal role in many biological systems. However, the intensity of the magnetic forces exerted between magnetic bodies is usually low, which demands the development of ultra-sensitivity tools for proper sensing. In this framework, magnetic force microscopy (MFM) offers excellent lateral resolution and the possibility of conducting single-molecule studies like other single-probe microscopy (SPM) techniques. This comprehensive review attempts to describe the paramount importance of magnetic forces for biological applications by highlighting MFM's main advantages but also intrinsic limitations. While the working principles are described in depth, the article also focuses on novel micro- and nanofabrication procedures for MFM tips, which enhance the magnetic response signal of tested biomaterials compared to commercial nanoprobes. This work also depicts some relevant examples where MFM can quantitatively assess the magnetic performance of nanomaterials involved in biological systems, including magnetotactic bacteria, cryptochrome flavoproteins, and magnetic nanoparticles that can interact with animal tissues. Additionally, the most promising perspectives in this field are highlighted to make the reader aware of upcoming challenges when aiming toward quantum technologies.