Superparamagnetic Nanoparticles Research Articles

Nature-inspired fungal fusarinine C-powered dual-mode fluorometric/colorimetric biosensing of fecal Helicobacter pylori with high-reliability

Conventional diagnostic approaches for Helicobacter pylori lack sufficient sensitivity, accuracy, and flexibility, especially for low-density H. pylori infection. To overcome this limitation, we developed a highly reliable fluorometric/colorimetric dual-mode biosensing technique to detect minute quantities of H. pylori in human stool samples. Inspired by natural porphyrins, we discovered that the water-soluble fungal siderophore fusarinine C (FsC) emitted intense green fluorescence owing to intramolecular through-bond and intermolecular through-space conjugation, and turned reddish upon coordination with Fe3+. With FsC as an intrinsic fluorometric/colorimetric probe, a dual-mode biosensor was developed. It included an enrichment module of truncated H. pylori-specific-aptamer-modified superparamagnetic nanoparticles to capture H. pylori from samples, and a transduction module of alginate conjugated with FsC[Fe3+] and an optimized amount of FsC without Fe3+ to amplify the captured H. pylori to fluorescent and/or color signals. Remarkably, significantly increased sensitivity was achieved for this biosensor, with an actual limit of detection of 5 CFU/mL and single-cell-level detection resolution, as validated using laser-tweezer-sorted single H. pylori cells. Moreover, highly reliable dual-mode detection of low-density H. pylori (between 5 and 10 CFU/mL) was demonstrated. Using the colorimetric mode, a smartphone-biosensor platform for sensitive point-of-care testing of fecal H. pylori within 20 min was demonstrated, outperforming the clinical fecal antigen test strips; meanwhile, the fluorometric mode of the biosensor, owing to its greater sensitivity, can verify the colorimetric detection of minute H. pylori. This study first showcased a FsC-powered dual-mode biosensor for ultra-sensitive and accurate point-of-care detection of H. pylori with high reliability.

Induction heating of magnetic nanoparticles: role of thermo-physical properties of the coating moieties

Superparamagnetic nanoparticles (MNPs) are utilized for magnetic fluid hyperthermia (MFH)-based cancer therapeutics, where the MNPs are surface functionalized to impart desired stability and biological properties. In this study, the MFH properties of palmitic (PA) and stearic (SA) acid-coated superparamagnetic Fe3O4 MNPs, with similar sizes (∼ 10 ± 0.8 nm, and ∼ 11 ± 0.7 nm, respectively), and saturation magnetizations (∼ 40.8 emu/g, and ∼ 41 emu/g, respectively), are systematically probed to understand the role of the thermo-physical properties of the coating moieties on the MFH efficiency. PA and SA-coated MNPs are prepared using a one-step microwave-assisted co-precipitation technique, and the presence of the surface coatings is confirmed using Fourier transform infrared spectroscopy and thermogravimetric analyses. Magneto-calorimetric studies show a high induction heating efficiency, surpassing the threshold of MFH for a biologically relevant field-frequency range. The maximum heating efficiencies are found to be ∼ 164.5 ± 5.4 W/gFe and ∼ 223.9 ± 6.4 W/gFe for the PA and SA-coated MNPs, respectively. This indicates ∼ 36.1 % higher specific absorption rate (SAR) for the SA-coated MNPs under similar experimental conditions, even though the magneto-structural properties are identical for the PA and SA-coated MNPs. Further, finite element modelling is utilized to investigate the thermal transport from the magnetic core to the surrounding medium, where the thermo-physical properties of the coating moieties are considered. Finite element simulations indicate ∼ 32.6 % higher SAR for the SA-coated MNPs, which is consistent with the experimental findings. The higher SAR for the SA-coated MNPs is attributed to the ∼ 1.7 times higher thermal diffusivity of SA. The proposed model is experimentally validated using a third system consisting of lauric acid-coated Fe3O4 MNPs with comparable magneto-structural properties. Further, significant temperature rise in a tissue-equivalent agar medium and good bio-compatibility, as indicated by the in vitro cyto-toxicity studies, make the prepared MNPs potential candidates for MFH applications. The obtained results provide deeper insight into the role of the thermo-physical properties of the coating moieties on the induction heating efficiency of superparamagnetic MNPs.

Integrated micro/nano drug delivery system based on magnetically responsive phase-change droplets for ultrasound theranostics.

Phase-change droplets (PCDs) are intelligent responsive micro and nanomaterials developed based on micro/nano bubbles. Subject to external energy inputs such as temperature and ultrasound, the core substance, perfluorocarbon (PFC), undergoes a phase transition from liquid to gas. This transformation precipitates alterations in the PCDs' structure, size, ultrasound imaging capabilities, drug delivery efficiency, and other pertinent characteristics. This gives them the ability to exhibit "intelligent responses". This study utilized lipids as the membrane shell material and perfluorohexane (PFH) as the core to prepare lipid phase-change droplets. Superparamagnetic nanoparticles (PEG-functionalized Fe3O4 nanoparticles) and the anti-tumor drug curcumin (Cur) were loaded into the membrane shell, forming magnetic drug-loaded phase-change droplets (Fe-Cur-NDs). These nanoscale phase-change droplets exhibited excellent magnetic resonance/ultrasound imaging capabilities and thermal/ultrasound-mediated drug release. The Fe-Cur-NDs showed excellent anti-tumor efficacy for the MCF-7 cells under low-intensity focused ultrasound (LIFU) guidance in vitro. Therefore, Fe-Cur-NDs represent a promising smart responsive theranostic integrated micro/nano drug delivery system.

Tuning Surface, Phase, and Magnetization of Superparamagnetic Magnetite by Ionic Liquids: Single-Step Microwave-Assisted Synthesis.

Achieving colloidal and chemical stability in ferrofluids by surface modification requires multiple steps, including purification, ex situ modification steps, and operation at high temperatures. In this study, a single-step microwave-assisted methodology is developed for iron oxide nanoparticle (IONP) synthesis utilizing a series of imidazolium-based ionic liquids (ILs) with chloride, bis(trifluoromethylsulfonyl)imide, and pyrrolide anions as the reaction media, thus eliminating the use of volatile organics while enabling rapid synthesis at 80 °C as well as in situ surface functionalization. The characterized surface functionality, hydrodynamic particle size, magnetization, and colloidal stability of the IONPs demonstrate a strong dependence on the IL structure, ion coordination strength, reactivity, and hydrophilicity. The IONPs present primarily a magnetite (Fe3O4) phase with superparamagnetism with the highest saturation magnetization at 81 and 73 emu/g at 10 and 300 K, respectively. Depending on the IL coating, magnetization and exchange anisotropy decrease by 20 and 2-3 emu/g (at 35 wt % IL), respectively, but still represent the highest magnetization achieved for coated IONPs by a coprecipitation method. Further, the surface-functionalized superparamagnetic magnetite nanoparticles show good dispersibility and colloidal stability in water and dimethyl sulfoxide at 0.1 mg/mL concentration over the examined 3 month period. This study reports on the intermolecular and chemical interactions between the particle surface and the ILs under synthetic conditions as they relate to the magnetic and thermal properties of the resulting IONPs that are well suited for a variety of applications, including separation and catalysis.

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 30s of incubation through both caveolin-dependent endocytosis and micropinocytosis. However, incubation for a longer time (1h 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.

A comprehensive approach to characterize navigation instruments for magnetic guidance in biological systems

Achieving non-invasive spatiotemporal control over cellular functions, tissue organization, and behavior is a desirable aim for advanced therapies. Magnetic fields, due to their negligible interaction with biological matter, are promising for in vitro and in vivo applications, even in deep tissues. Particularly, the remote manipulation of paramagnetic (including superparamagnetic and ferromagnetic, all with a positive magnetic susceptibility) entities through magnetic instruments has emerged as a promising approach across various biological contexts. However, variations in the properties and descriptions of these instruments have led to a lack of reproducibility and comparability among studies. This article addresses the need for standardizing the characterization of magnetic instruments, with a specific focus on their ability to control the movement of paramagnetic objects within organisms. While it is well known that the force exerted on magnetic particles depends on the spatial variation (gradient) of the magnetic field, the magnitude of the field is often overlooked in the literature. Therefore, we comprehensively analyze and discuss both actors and propose a novel descriptor, termed ‘effective gradient’, which combines both dependencies. To illustrate the importance of both factors, we characterize different magnet systems and relate them to experiments involving superparamagnetic nanoparticles. This standardization effort aims to enhance the reproducibility and comparability of studies utilizing magnetic instruments for biological applications.

Removal of Metal Ions from Wastewater Using Co‐integrated Superparamagnetic Nanoparticles

AbstractThe column performance of silica‐coated, amino‐functionalized, superparamagnetic nanoparticles co‐integrated with Cynodon dactylon and Murraya koenigii plant extracts for the removal of CuII ions was evaluated. The co‐integrated nanoparticles were used as sorbent materials in fixed‐bed column studies, and the effects of inlet concentration, adsorbent bed depth, and flow rate were analyzed. Breakthrough time was calculated for various CuII inlet concentrations, depths of the adsorbent bed, and volumetric flow rates. Models such as Thomas, Yoon‐Nelson, and the bed depth model were evaluated to determine the experimental fit. The maximum breakthrough time for CuII ions of 1200 min was attained for a CuII inlet concentration of 100 mg L–1, sorbent bed depth of 3 cm, and volumetric flow rate of 1 mL min–1.

Exploring induced microstructural changes in magnetically modified crude oils through nonlinear rheology and magnetometry

Adsorptive phenomena involving dispersed iron oxide superparamagnetic nanoparticles and asphaltenes in crude oil have been profiled as promising technological alternatives, particularly since these interactions can induce significant structural changes within the oil matrices, effectively inhibiting the formation of complex long-range viscoelastic structures. Furthermore, the effect of adsorbed asphaltenes on magnetic dipolar interactions among particles has been proven, showing the formation of multiple asphaltene layers that stimulate a steric repulsive barrier. Despite the discussed hindering phenomena, this research demonstrated the effectiveness of the sequence of physical processes framework to provide intra-cycle structure-rheological interpretations in large amplitude oscillatory shear of a ferrofluid-modified heavy oil, upon the application of an external magnetic field. The analysis proved that disordered nanoparticle/asphaltene aggregates are highly extended and naturally formed in the absence of magnetic forces. In contrast, in the presence of a perpendicular field applied by a controlled rate magneto-rheometer, the formation of interacting structural aggregates of several hundred nanometers was observed, analogous to magnetorheological fluids. These results were validated by adjusting a phenomenological model that effectively represented the intricate processes involved in the formation and reorientation of aggregates, based on the experimental data acquired from zero-field-cooled and field-cooled magnetization curves. This revealed a distinct blocking temperature distribution at around 274 K, which was linked to Brownian relaxation phenomena exhibited by nanoparticle aggregates. In this regard, this research provided a precise extended description of the effect of magnetic fields on the microstructural organization of complex fluids using nonlinear rheology and magnetometry.

Synthesis and Characterization of B4C-Based Multifunctional Nanoparticles for Boron Neutron Capture Therapy Applications

Nanoparticles composed of inorganic boron-containing compounds represent a promising candidate as 10B carriers for BNCT. This study focuses on the synthesis, characterization, and assessment of the biological activity of composite nanomaterials based on boron carbide (B4C). Boron carbide is a compelling alternative to borated molecules due to its high volumetric B content, prolonged retention in biological systems, and low toxicity. These attributes lead to a substantial accumulation of B in tissues, eliminating the need for isotopically enriched compounds. In our approach, B4C nanoparticles were included in composite nanostructures with ultrasmall superparamagnetic nanoparticles (SPIONs), coated with poly (acrylic acid), and further functionalized with the fluorophore DiI. The successful internalization of these nanoparticles in HeLa cells was confirmed, and a significant uptake of 10B was observed. Micro-distribution studies were conducted using intracellular neutron autoradiography, providing valuable insights into the spatial distribution of the nanoparticles within cells. These findings strongly indicate that the developed nanomaterials hold significant promise as effective carriers for 10B in BNCT, showcasing their potential for advancing cancer treatment methodologies.

Superparamagnetic iron oxide nanoparticle enhanced percutaneous microwave ablation: Ex-vivo characterization using magnetic resonance thermometry.

Percutaneous microwave ablation (pMWA) is a minimally invasive procedure that uses a microwave antenna placed at the tip of a needle to induce lethal tissue heating. It can treat cancer and other diseases with lower morbidity than conventional surgery, but one major limitation is the lack of control over the heating region around the ablation needle. Superparamagnetic iron oxide nanoparticles have the potential to enhance and control pMWA heating due to their ability to absorb microwave energy and their ease of local delivery. The purpose of this study is to experimentally quantify the capabilities of FDA-approved superparamagnetic iron oxide Feraheme nanoparticles (FHNPs) to enhance and control pMWA heating. This study aims to determine the effectiveness of locally injected FHNPs in increasing the maximum temperature during pMWA and to investigate the ability of FHNPs to create a controlled ablation zone around the pMWA needle. PMWA was performed using a clinical ablation system at 915MHz in ex-vivo porcine liver tissues. Prior to ablation, 50uL 5mg/mL FHNP injections were made on one side of the pMWA needle via a 23-gauge needle. Local temperatures at the FHNP injection site were directly compared to equidistant control sites without FHNP. First, temperatures were compared using directly inserted thermocouples. Next, temperatures were measured non-invasively using magnetic resonance thermometry (MRT), which enabled comprehensive four-dimensional (volumetric and temporal) assessment of heating effects relative to nanoparticle distribution, which was quantified using dual-echo ultrashort echo time (UTE) subtraction MR imaging. Maximum heating within FHNP-exposed tissues versus control tissues were compared at multiple pMWA energy delivery settings. The ability to generate a controlled asymmetric ablation zone using multiple FHNP injections was also tested. Finally, intra-procedural MRT-derived heat maps were correlated with gold standard gross pathology using Dice similarity analysis. Maximum temperatures at the FHNP injection site were significantly higher than control (without FHNP) sites when measured using direct thermocouples (93.1±6.0°C vs. 57.2±8.1°C, p=0.002) and using non-invasive MRT (115.6±13.4°C vs. 49.0±10.6°C, p=0.02). Temperature difference between FHNP-exposed and control sites correlated with total energy deposition: 66.6±17.6°C, 58.1±8.5°C, and 20.8±9.2°C at high (17.5±2.2kJ), medium (13.6±1.8kJ), and low (8.8±1.1kJ) energies, respectively (all pairwise p<0.05). Each FHNP injection resulted in a nanoparticle distribution within 0.9±0.2cm radially of the injection site and a local lethal heating zone confined to within 1.1±0.4cm radially of the injection epicenter. Multiple injections enabled a controllable, asymmetric ablation zone to be generated around the ablation needle, with maximal ablation radius on the FHNP injection side of 1.6±0.2cm compared to 0.7±0.2cm on the non-FHNP side (p=0.02). MRT intra-procedural predicted ablation zone correlated strongly with post procedure gold-standard gross pathology assessment (Dice similarity 0.9). Locally injected FHNPs significantly enhanced pMWA heating in liver tissues, and were able to control the ablation zone shape around a pMWA needle. MRI and MRT allowed volumetric real-time visualization of both FHNP distribution and FHNP-enhanced pMWA heating that was useful for intra-procedural monitoring. This work strongly supports further development of a FHNP-enhanced pMWA paradigm; as all individual components of this approach are approved for patient use, there is low barrier for clinical translation.

The effect of magnetic field on the orientational ordering of easy magnetization axes in superparamagnetic nanoparticles

The active use of nanoparticles in modern biomedical applications and technologies requires reliable theoretical models capable of predicting physical properties. The effect of a static magnetic field on the orientational ordering of the easy magnetization axes in an ensemble of superparamagnetic nanoparticles (SNPs) is studied using a combination of statistical-mechanical theory and computer simulations. The magnetic dipole-dipole interaction between particles is taken into account within the framework of the modified mean-field approach. The alignment distributions of the easy magnetization axes of the SNPs and the static magnetic characteristics of the ferrocomposite are analyzed. The presence of even weak interparticle magneto-dipole interactions results in a notable enhancement of the magnetic susceptibility of the ferrocomposite.

Unveiling the effects of azimuthal angle and superimposed magnetic bias fields on the nonlinear magnetization dynamics of superparamagnetic nanoparticles

Unveiling the effects of azimuthal angle and superimposed magnetic bias fields on the nonlinear magnetization dynamics of superparamagnetic nanoparticles

Facile green fabrication of magnetite nanoparticles using an aqueous flower extract of Murraya paniculata (L) Jack for an efficient removal of organic dye pollutant, antibacterial activities

This article reports, the plant-mediated synthesis of Magnetite nanoparticles achieved by utilising an aqueous flower extract of Murraya paniculata (L) Jack (FMPM NPs). The active compounds are phenols, alkaloids, flavones and terpenoids in the aqueous flower extract of Murraya paniculata act as ligating agents to synthesize novel green superparamagnetic magnetite nanoparticles by the coprecipitation method. As prepared FMPM NPs have been characterized by a range of spectroscopic and microscopic techniques. All spectroscopic and microscopic results confirmed the occurrence of pure FMPM NPs. Fourier transform-infrared spectroscopy (FTIR) shows the presence of a Fe-O bond and the band gap was found to be 2.57 eV for FMPM NPs. The surface area of the synthesized nanoparticles was 70.31 m2/g evaluated by BET analysis. The elemental analysis has been performed by the XPS technique. The XRD pattern revealed the crystal size of 14.12 nm of FMPM NPs. TEM images show the spherical shaped FMPM NPs with an average particle size of 11.58 nm. SEM results clearly show spherically shaped FMPM NPs. The superparamagnetic character of FMPM NPs is revealed by the VSM curve and saturation magnetization (Ms) value of 58 emu/g. FMPM NPs used for photocatalytic activity, tested against gram positive, gram negative and antifungal bacteria. As prepared FMPM NPs. showed 93 % removal efficiency of Fast sulphon black-F dye pollutant. Moreover, FMPM NPs efficiently inhibit the growth of Enterococcus faecalis and Penicillium chrysogenum. The current research is for the fabrication of magnetite nanoparticles utilising novel green source and examining their applications.

1H Spin-Lattice Relaxation Processes in Solutions of H2N-Fe3O4 Nanoparticles: Insights from NMR Relaxometry.

1H spin-lattice relaxation experiments have been performed for water and glycerol/water solutions of H2N-Fe3O4 superparamagnetic nanoparticles (NPs) of about 7 nm diameter. The experiments encompass a broad frequency range covering 3 orders of magnitude, from 10 kHz to 10 MHz (referring to 1H resonance frequency), and have been performed in the temperature range from 298 to 313 K, varying the concentration of the superparamagnetic species. This extensive dataset has been used for twofold purposes. The first one is to serve as a challenge for thorough tests of theoretical models describing nuclear relaxation in solutions of superparamagnetic NPs, depending on their magnetic properties and dynamics of the solvent molecules. The challenge is posed by the wish to reproduce the data in a broad range of magnetic fields (not only at high fields) and by the need to explain the differences in the relaxation scenarios for water and glycerol/water solutions by varying only the solvent parameters. The second purpose is to get insights into the magnetic properties (electronic relaxation properties) of the nanoparticles due to their high applicational potential.

Yolk‐Shell Structure and Spin‐Polarized Surface Capacitance Enable FeS Stable and Fast Ion Transport in Sodium‐Ion Batteries

AbstractIron sulfide (FeS) has been extensively studied as sodium‐ion battery anodes due to its high theoretical capacity (609 mAh g−1), but its large volume expansion and low electrical conductivity result in unsatisfactory cycling life and poor rate performance. Moreover, the sodium ion storage mechanism of FeS at a voltage range of 0.01–1 V involving conversion reactions and subsequent ion storage process is unclear yet. Here, the study proposes a vapor‐pressure induced synthesis route to fabricate FeS/C yolk‐shell structure that ultrathin carbon layers coat on the surface of FeS nanosheets, which can accommodate volume expansion of FeS during sodiation observed via in situ transmission electron microscope and improve its electrical conductivity. Remarkably, an in situ magnetometry reveals that vast spin‐polarized electrons can be injected into superparamagnetic Fe nanoparticles (≈3 nm) formed during conversion reaction to induce evolution of electrode magnetization between 0.01 and 1 V, during which spin‐polarized surface capacitance effect occurs at Fe/Na2S interfaces to increase extra ion storage and boost ion transport stably. Consequently, the FeS/C yolk‐shell nanosheets deliver a high reversible capacity of 664.9 mAh g−1 at 0.1 A g−1, and 300.4 mAh g−1 after 10 000 cycles at 10 A g−1 with a capacity retention of 81.1%.

EphA2-specific microvesicles derived from tumor cells facilitate the targeted delivery of chemotherapeutic drugs for osteosarcoma therapy

Despite advances in surgery and chemotherapy, the survival of patients with osteosarcoma (OS) has not been fundamentally improved over the last two decades. Microvesicles (MVs) have a high cargo-loading capacity and are emerging as a promising drug delivery nanoplatform. The aim of this study was to develop MVs as specifically designed vehicles to enable OS-specific targeting and efficient treatment of OS. Herein, we designed and constructed a nanoplatform (YSA-SPION-MV/MTX) consisting of methotrexate (MTX)-loaded MVs coated with surface-carboxyl Fe3O4 superparamagnetic nanoparticles (SPIONs) conjugated with ephrin alpha 2 (EphA2)-targeted peptides (YSAYPDSVPMMS, YSA). YSA-SPION-MV/MTX showed an effective targeting effect on OS cells, which was depended on the binding of the YSA peptide to EphA2. In the orthotopic OS mouse model, YSA-SPION-MV/MTX effectively delivered drugs to tumor sites with specific targeting, resulting in superior anti-tumor activity compared to MTX or MV/MTX. And YSA-SPION-MV/MTX also reduced the side effects of high-dose MTX. Taken together, this strategy opens up a new avenue for OS therapy. And we expect this MV-based therapy to serve as a promising platform for the next generation of precision cancer nanomedicines.Graphical

A new frontier in imaging: natural ore-sourced superparamagnetic magnetite nanoparticles for multi-modal imaging

A new frontier in imaging: natural ore-sourced superparamagnetic magnetite nanoparticles for multi-modal imaging

Magnetic Hydroxyapatite Nanoparticles in Regenerative Medicine and Nanomedicine.

This review focuses on the latest advancements in magnetic hydroxyapatite (mHA) nanoparticles and their potential applications in nanomedicine and regenerative medicine. mHA nanoparticles have gained significant interest over the last few years for their great potential, offering advanced multi-therapeutic strategies because of their biocompatibility, bioactivity, and unique physicochemical features, enabling on-demand activation and control. The most relevant synthetic methods to obtain magnetic apatite-based materials, either in the form of iron-doped HA nanoparticles showing intrinsic magnetic properties or composite/hybrid compounds between HA and superparamagnetic metal oxide nanoparticles, are described as highlighting structure-property correlations. Following this, this review discusses the application of various magnetic hydroxyapatite nanomaterials in bone regeneration and nanomedicine. Finally, novel perspectives are investigated with respect to the ability of mHA nanoparticles to improve nanocarriers with homogeneous structures to promote multifunctional biological applications, such as cell stimulation and instruction, antimicrobial activity, and drug release with on-demand triggering.

Magnetic hyperthermia in tissue-like media: Finite element simulation, experimental validation, parametric variations, and calibration studies

We report the experimental characterization and finite element modeling of magnetic fluid hyperthermia (MFH) in tissue-like media using tetramethyl ammonium hydroxide coated superparamagnetic iron oxide magnetic nanoparticles (MNPs) of size ∼19.6 ± 1.2 nm, prepared using a co-precipitation technique. MFH properties are probed for the MNPs in ∼1 wt. % agar, resembling the tumor and surrounding normal tissues. The field-induced temperature rise (ΔT) is experimentally measured in real-time utilizing an infrared camera. A finite element model (FEM) is utilized to simulate the spatiotemporal variations in the thermal profiles, which are found to be in good agreement with the experimental data. FEM-based parametric studies reveal that the thermal conductivity of the medium is the most significant parameter influencing the thermal profiles. The spatiotemporal variations in the thermal profiles are numerically studied for seven different tissues, and the obtained results indicate the highest ΔT for the breast tissue in the tumor and the surrounding regions, which is due to the lowest volumetric specific heat and the highest thermal conductivity of the breast tissue, respectively. Numerical studies on the thermal profiles for sub-surface tumors with parametrically varying depths indicate a strong exponential correlation between the surface and tumor temperature, where the regression coefficients are found to be correlated with the thermo-physical properties of the tissues. The obtained findings are beneficial for developing a simplistic and easily deployable framework for a priori generation of the thermal profiles for various tissues during MFH, which is useful for appropriate planning and parameter selection for MFH-based therapy.

Superparamagnetic Iron Oxide Nanoparticle Implantation and Magnetic Field Exposure Modulate Bone Microarchitecture Following Spinal Cord Injury in Adult Male Rats.

Background: Osteoporosis is one of the detrimental effects of spinal cord injury (SCI), leading to bone loss. It has already been established that superparamagnetic nanoparticles when exposed to an external magnetic field (MF) show strong magnetisation and promote locomotor recovery. Purpose: The aim of the present study is to explore the role of magnetised nanoparticles in ameliorating SCI-induced osteoporosis. Methods: The rats were divided into Sham, SCI, SCI+MF, SCI+V, SCI+NP and SCI+NP+MF groups. A complete transection was performed at the T13 level, followed by iron oxide nanoparticle implantation along with MF exposure for 7 or 14 days. Results: A significant increase in locomotor score was evident at day 5 in all groups except in the SCI+V group, and at day 7, all groups showed a significant increase in Basso, Beattie and Bresnahan score as compared to the pre-surgery score at week 1 of the study period. A significant decrease in bone volume/total volume ratio and trabecular thickness and increase in trabecular separation were observed in all groups as compared to Sham. A significant increase in trabecular thickness in the SCI+NP+MF group as compared to the SCI+MF group was observed after one week. After two weeks, the SCI+MF group showed a significant increase in locomotor scores at days 5 and 13 as compared to the SCI, SCI+V and SCI+NP groups. Bone loss was significantly observed in all groups except SCI+MF, as compared to Sham. Cortical bone showed no significant change at both time points. On histopathological examination of the spinal cord, we observed significant improvement in lesion volume in SCI+MF and SCI+NP+MF groups after one week, whereas only the SCI+NP+MF group showed a significant decrease after two weeks. Conclusion: Electromagnetic field stimulation partially restored bone architecture after superparamagnetic nanoparticle implantation, which may be due to reduced lesion volume and improved locomotor behaviour.