Distribution Of Magnetic Nanoparticles Research Articles

Extraction method of nanoparticles concentration distribution from magnetic particle image and its application in thermal damage of magnetic hyperthermia

Magnetic particle imaging (MPI) technology can generate a real-time magnetic nanoparticle (MNP) distribution image for biological tissues, and its use can overcome the limitations imposed in magnetic hyperthermia treatments by the unpredictable MNP distribution after the intratumoral injection of nanofluid. However, the MNP concentration distribution is generally difficult to be extracted from MPI images. This study proposes an approach to extract the corresponding concentration value of each pixel from an MPI image by a least squares method (LSM), which is then translated as MNP concentration distribution by an interpolation function. The resulting MPI-based concentration distribution is used to evaluate the treatment effect and the results are compared with the ones of two baseline cases under the same dose: uniform distribution and MPI-based distribution considering diffusion. Additionally, the treatment effect for all these cases is affected by the blood perfusion rate, which is also investigated deeply in this study. The results demonstrate that the proposed method can be used to effectively reconstruct the concentration distribution from MPI images, and that the weighted LSM considering a quartic polynomial for interpolation provides the best results with respect to other cases considered. Furthermore, the results show that the uniformity of MNP distribution has a positive correlation with both therapeutic temperature distribution and thermal damage degree for the same dose and a critical power dissipation value in the MNPs. The MNPs uniformity inside biological tissue can be improved by the diffusion behavior after the nanofluid injection, which can ultimately reflect as an improvement of treatment effect. In addition, the blood perfusion rate considering local temperature can have a positive effect on the treatment compared to the case which considers a constant value during magnetic hyperthermia.

Magnetically Stimulable Graphene Oxide/Polypropylene Nanocomposites.

Core-shell magnetic air-stable nanoparticles have attracted increasing interest in recent years. Attaining a satisfactory distribution of magnetic nanoparticles (MNPs) in polymeric matrices is difficult due to magnetically induced aggregation, and supporting the MNPs on a nonmagnetic core-shell is a well-established strategy. In order to obtain magnetically active polypropylene (PP) nanocomposites by melt mixing, the thermal reduction of graphene oxides (TrGO) at two different temperatures (600 and 1000 °C) was carried out, and, subsequently, metallic nanoparticles (Co or Ni) were dispersed on them. The XRD patterns of the nanoparticles show the characteristic peaks of the graphene, Co, and Ni nanoparticles, where the estimated sizes of Ni and Co were 3.59 and 4.25 nm, respectively. The Raman spectroscopy presents typical D and G bands of graphene materials as well as the corresponding peaks of Ni and Co nanoparticles. Elemental and surface area studies show that the carbon content and surface area increase with thermal reduction, as expected, following a reduction in the surface area by the support of MNPs. Atomic absorption spectroscopy demonstrates about 9-12 wt % metallic nanoparticles supported on the TrGO surface, showing that the reduction of GO at two different temperatures has no significant effect on the support of metallic nanoparticles. Fourier transform infrared (FT-IR) spectroscopy shows that the addition of a filler does not alter the chemical structure of the polymer. Scanning electron microscopy of the fracture interface of the samples demonstrates consistent dispersion of the filler in the polymer. The TGA analysis shows that, with the incorporation of the filler, the initial (Tonset) and maximum (Tmax) degradation temperatures of the PP nanocomposites increase up to 34 and 19 °C, respectively. The DSC results present an improvement in the crystallization temperature and percent crystallinity. The filler addition slightly enhances the elastic modulus of the nanocomposites. The results of the water contact angle confirm that the prepared nanocomposites are hydrophilic. Importantly, the diamagnetic matrix is transformed into a ferromagnetic one with the addition of the magnetic filler.

Magnetomotive Ultrasound Shear Wave Elastography (MMUS-SWE): A Validation Study From Simulations to Experiments.

Ultrasound elastography is a functional imaging method that enables the measurement of soft tissue elasticity, which is associated with the pathological process of many diseases. However, the measurement area of the conventional elastography method is subjectively selected. Inspired by the targeted imaging technology, we propose a method of magnetomotive ultrasound shear wave elastography (MMUS-SWE). This method utilizes the magnetic force between the magnetic nanoparticles (MNPs) and the external magnetic field to generate shear waves. Then, it can detect the distribution of MNPs and the elasticity of the tissue around the MNPs. As MNPs have been widely used for targeted labeling, the strategy to induce local vibration by MNPs will be more specific than that of the conventional SWE. In this study, the theoretical feasibility was verified by the finite element simulation model. Then, an experimental system was built, and the experimental feasibility of the method was demonstrated through phantom experiments, in vitro tissue experiments, and in vivo experiments. The results show that the distribution of the MNPs and the elastic information of tissues surrounding the MNPs can be detected simultaneously. This technology is expected to realize targeted elasticity measurement based on the MNPs and has potential applications for disease diagnosis.

System Matrix Reconstruction Algorithm for Thermoacoustic Imaging With Magnetic Nanoparticles Based on Acoustic Reciprocity Theorem.

According to the acoustic reciprocity theorem (ART), we propose a system matrix reconstruction algorithm of thermoacoustic imaging for magnetic nanoparticles (MNPs) by a single-pulse magnetic field. In both cases of inhomogeneous and homogeneous acoustic velocity, we respectively derive the linear equation between the sound pressure detection value and the distribution of MNPs. The image reconstruction problem is converted to an inverse matrix solution by using the truncated singular value decomposition (TSVD) method. In forward problem, the calculated forward results are consistent with the simulated thermoacoustic signal signals. In inverse problem, we build the two-dimensional breast cancer model. The TSVD method based on the ART faithfully reflects the distribution of abnormal tissue labeled by the MNPs. In the experiment, the biological sample injected with the MNPs is used as the imaging target. The reconstructed image well reflects the cross-sectional images of the MNPs area. The TSVD method based on the ART takes into account energy attenuation and inhomogeneous acoustic velocity, and use a non-focused broadband ultrasonic transducer as the receiver to obtain a larger imaging field-of-view (FOV). By comparing the image metrics, we prove that the algorithm is superior to the traditional time reversal method. The TSVD method based on the ART can better suppress noise, which is expected to reduce the cost by reducing the number of detectors. It is of great significance for future clinical applications.

Effect of porous heat transfer model on different equivalent thermal dose methods considering an experiment-based nanoparticle distribution during magnetic hyperthermia

Magnetic fluid hyperthermia damages malignant cells by keeping the therapeutic temperature within a specific range after magnetic nanoparticles (MNPs) are exposed to an alternating magnetic field. The temperature distribution inside bio-tissue is usually predicted by a classic Pennes bio-heat transfer equation, which considers a heat source due to a homogeneous distribution for MNPs. Aiming at this problem, this study compares the Pennes model to a porous heat transfer model, named local thermal non-equilibrium equation, by considering an experiment-based MNPs distribution, and evaluates the thermal damage degree for malignant tissue by two different thermal dose methods. In addition, this study evaluates the effect of porosity and different blood perfusion rates on both effective treatment temperature and equivalent thermal dose. Simulation results demonstrate that different bio-heat transfer models can result in significant differences in both the treatment temperature profile and the thermal damage degree for tumor region under the same power dissipation of MNPs. Furthermore, scenarios considering a temperature-dependent blood perfusion rate or a lower porosity can have a positive effect on the temperature distribution inside tumor, while having a lower value in the maximum equivalent thermal dose in both thermal dose evaluation methods.

Design and Assessment of a Novel Biconical Human-Sized Alternating Magnetic Field Coil for MNP Hyperthermia Treatment of Deep-Seated Cancer.

Magnetic nanoparticle (MNP) hyperthermia therapy is a treatment technique that can be used alone or as an adjunct to radiation and/or chemotherapies for killing cancer cells. During treatment, MNPs absorb a part of electromagnetic field (EMF) energy and generate localized heat when subjected to an alternating magnetic field (AMF). The MNP-absorbed EMF energy, which is characterized by a specific absorption rate (SAR), is directly proportional to AMF frequency and the magnitude of transmitting currents in the coil. Furthermore, the AMF penetrates inside tissue and induces eddy currents in electrically conducting tissues, which are proportional to the electric field (J = σE). The eddy currents produce Joule heating (<J·E> = 0.5·σ·E2) in the normal tissue, the rate of energy transfer to the charge carriers from the applied electric fields. This Joule heating contains only the electric field because the magnetic field is always perpendicular to the velocity of the conduction charges, i.e., it does not produce work on moving charge. Like the SAR due to MNP, the electric field produced by the AMF coil is directly proportional to AMF frequency and the magnitude of transmitting currents in the coil. As a result, the Joule heating is directly proportional to the square of the frequency and transmitter current magnitude. Due to the fast decay of magnetic fields from an AMF coil over distance, MNP hyperthermia treatment of deep-seated tumors requires high-magnitude transmitting currents in the coil for clinically achievable MNP distributions in the tumor. This inevitably produces significant Joule heating in the normal tissue and becomes more complicated for a standard MNP hyperthermia approach for deep-seated tumors, such as pancreatic, prostate, liver, lung, ovarian, kidney, and colorectal cancers. This paper presents a novel human-sized AMF coil and MNP hyperthermia system design for safely and effectively treating deep-seated cancers. The proposed design utilizes the spatial distribution of electric and magnetic fields of circular coils. Namely, it first minimizes the SAR due to eddy currents in the normal tissue by moving the conductors away from the tissue (i.e., increasing coils' radii), and second, it increases the magnetic field at the targeted area (z = 0) due to elevated coils (|z| > 0) by increasing the radius of the elevated coils (|z| > 0). This approach is a promising alternative aimed at overcoming the limitation of standard MNP hyperthermia for deep-seated cancers by taking advantage of the transmitter coil's electric and magnetic field distributions in the human body for maximizing AMF in tumor regions and avoiding damage to normal tissue. The human-sized coil's AMF, MNP activation, and eddy current distribution characteristics are investigated for safe and effective treatment of deep-seated tumors using numerical models. Namely, computational results such as AMF, Joule heating SAR, and temperature distributions are presented for a full-body, 3D human model. The SAR and temperature distributions clearly show that the proposed human-sized AMF coil can provide clinically relevant AMF to the region occupied by deep-seated cancers for the application of MNP hyperthermia therapy while causing less Joule heating in the normal tissues than commonly used AMF techniques.

Effects of injection rates and tissue diffusivity in magnetic nano-particle hyperthermia.

Effects of injection rate and tumor physiology on the diffusion of magnetic nano-particles (MNPs) and temperature profile during magnetic hyperthermia are investigated in this work. The study considers three injection rates (2.5 μL/min, 10 μL/min, and 40 μL/min), and two MNP diffusion coefficients (10-9 m2/s and 10-11 m2/s). The simulation of this physics has been done on 3D tumor surrounded by healthy tissue. Transient MNP distribution in tissue is evaluated using Darcy's flow model and the MNP transport (convection-diffusion) equation. The temperature profile in the tumor model is computed by solving Penne's bioheat transfer equation (PBHTE). Results show tumors with high collagen content (with low MNP diffusivity) are more restrictive towards MNP transport than tumors having low collagen content. Thus, tumors with low MNP diffusivity need a higher injection rate to increase the homogeneity of MNP concentration as well as temperature profile during thermo-therapy. Results also show that, MNP fluid injected with a higher injection rate produces a more uniform MNP concentration up to greater depth than the lower injection rate.

Spleen distribution and serum immune responses after acute administration of silica-conjugated magnetite (Fe3O4) nanoparticles

Cytokine storm is characterized by increased levels of proinflammatory cytokines. Magnetic nanoparticles (MNPs)-conjugated antibody therapy is promising in treating cytokine storms. This study will evaluate the time-dependent distribution of the silica-coated MNP (MNP-Si) in the spleen and consequent serum cytokine changes for 30 days. MNP-Si were administered to female BALB/c mice via the tail vein injection. The distribution of Fe in the spleen tissue was analyzed by ICP-MS both in control and MNP-Si-treated mice. Moreover, the acute immune toxicity in serum was investigated by analyzing IFN-γ and IL-6 levels. Fe in the control spleen is 0.98 × 106 μg/mg of dry weight. The highest average concentration of Fe in the spleen was measured on day 10 (1.4 × 106 μg/mg). And at day 30, Fe levels decreased to 1.0 × 106 μg/mg. IFN-γ levels significantly increase to a maximum on day 6 and remain elevated until day 30. IL-6 levels are not elevated after MNP-Si administration. Although the cytokines in tissue homogenates were elevated at day 20, the data are statistically non-significant. In conclusion, the proinflammatory cytokine IFN-γ levels were increased on day 6, indicating induced activation of macrophages and systemic inflammation after MNP-Si administration. Therefore, the dose and composition of the MNP-Si should be revised for potential usage for therapeutic purposes.

Mathematical Optimisation of Magnetic Nanoparticle Diffusion in the Brain White Matter.

Magnetic nanoparticles (MNPs) are a promising drug delivery system to treat brain diseases, as the particle transport trajectory can be manipulated by an external magnetic field. However, due to the complex microstructure of brain tissues, particularly the arrangement of nerve fibres in the white matter (WM), how to achieve desired drug distribution patterns, e.g., uniform distribution, is largely unknown. In this study, by adopting a mathematical model capable of capturing the diffusion trajectories of MNPs, we conducted a pilot study to investigate the effects of key parameters in the MNP delivery on the particle diffusion behaviours in the brain WM microstructures. The results show that (i) a uniform distribution of MNPs can be achieved in anisotropic tissues by adjusting the particle size and magnetic field; (ii) particle size plays a key role in determining MNPs' diffusion behaviours. The magnitude of MNP equivalent diffusivity is reversely correlated to the particle size. The MNPs with a dimension greater than 90 nm cannot reach a uniform distribution in the brain WM even in an external magnitude field; (iii) axon tortuosity may lead to transversely anisotropic MNP transport in the brain WM; however, this effect can be mitigated by applying an external magnetic field perpendicular to the local axon track. This study not only advances understanding to answer the question of how to optimise MNP delivery, but also demonstrates the potential of mathematical modelling to help achieve desired drug distributions in biological tissues with a complex microstructure.

A magnetic particle imaging in anisotropic magnetic manipulation platform

Magnetic particle imaging (MPI) has been demonstrated as the most promising imaging technology for monitoring distribution of magnetic nanoparticles (MNPs) at high sensitivity, high resolution, and fast imaging speed. Up to now, most published researches use the symmetric setups with multiple orthogonal pairs of coils. However, this poses a size and controllable degrees-of-freedom limitation for 3D manipulation tasks. The difficulties of field-free point (FFP) estimation and interferences of the core materials limit the MPI integration into other types of magnetic configuration. Thus, this paper presents a feasibility study of the integration of the MPI function in the anisotropic magnetic platform. A FFP generation method in anisotropic structures with various magnetic sources is derived and numerically investigated. The tracking performances are then demonstrated in both in-vitro and in-vivo experiments using one of the selected anisotropic structures. To date, the function of the proposed system is limited to tracking the particle. The experimental results on tracking the MNPs show a tracking accuracy of around 1 mm. Our proposed methodology allows the current magnetic actuation systems to upgrade the functionalities of simultaneous manipulation and localization.

Simultaneous estimation of magnetic moment and Brownian relaxation time distributions of magnetic nanoparticles based on magnetic particle spectroscopy for biosensing application.

Magnetic nanoparticles (MNPs) exhibit unique physicochemical characteristics owing to their comparable dimensions with important biological substances, high surface-to-volume ratios, size-dependent magnetic properties, and temperature sensitivity. In this study, we present a novel method for simultaneously estimating the magnetic moment and Brownian relaxation time distribution of MNPs based on AC magnetization harmonics. We provide a detailed description of the theoretical framework and experimental procedures. The dynamics of MNP magnetization are described using the Fokker-Planck equation, and a matrix equation is established to connect the magnetic moment, Brownian relaxation time, and magnetization harmonics. By employing a non-negative linear least squares algorithm with constraints, the magnetic moment and Brownian relaxation time distributions are inversed, which are then converted into the distributions of core sizes and hydrodynamic sizes. Finally, the estimated core size distribution reconstructed from M-H curves is consistent with the hydrodynamic size distribution measured by dynamic light scattering. This method is particularly useful for facilitating quantitative magnetic immunoassays.

Superparamagnetic hyperthermia and cytotoxicity properties of bimagnetic core–shell nanoparticles synthesized by solvothermal reflux method

Magnetic properties of spinel ferrites nanoparticles (NPs) were well studied for various applications, including biomedical applications such as magnetic hyperthermia agents, magnetic resonance imaging (MRI) contrast agents, targeted drug delivery agents, etc., Magnetic properties of these nanoparticles were altered by metal cations substitution as well as variation of size and shape of nanoparticles. Here hard–soft magnetic materials based magnetic exchange coupled bimagnetic CoFe2O4-CaFe2O4, and CaFe2O4-CoFe2O4 core–shell nanoparticles (CSNPs) with narrow size distribution were synthesized to alter their magnetic properties. Structural, morphology, magnetic, superparamagnetic hyperthermia (SPHT), and cytotoxicity properties of these NPs were reported. Unimagnetic phase CoFe2O4, CaFe2O4 nanoparticles were also studied for comparison. Though CaFe2O4 macrocrystals crystallizes in orthorhombic structure, CaFe2O4 nanocrystals crystallizes in cubic spinel structure whereas both macro- and nanoparticles of CoFe2O4 crystallizes in spinel structure. Scanning electron nanographs (electrongraphs) of all samples show narrow size distributed spherical particles of average particle size of around 10 nm and is confirmed by transmission electron nanographs. Room temperature magnetic hysteresis loop of all samples were shown superparamagnetic nature with very low coercive field. Bimagnetic CSNPs show higher specific heat generation rate (SHR) or specific magnetic field energy absorption rate (SAR) of superparamagnetic nanoparticles (474 W/g for CaFe2O4-CoFe2O4 CSNPs under H = 35.5 kAm−1 and f = 316 kHz field parameters ) compared to counterpart unimagnetic nanoparticles (407 W/g for CaFe2O4 NPs). However, the SAR decreases with increase of magnetic nanoparticles (MNPs) concentration in the dispersion medium due to reduced superparamagnetic relaxation time resulting from magnetic dipole interactions among dispersed nanoparticles. This is also confirmed in SPHT properties of dispersant removed CSNPs. Cytotoxicity studies show that cell viability increases with MNPs concentration due to increased colorimetric interference of iron oxide and inhomogeneous distribution of MNPs, due to magnetic interactions, among cell culture wells, at higher concentration. These CSNPs may be used for localized SPHT in cancer therapy.

Effect of magnetic nanoparticles on magnetic field homogeneity

The mechanism of magnetic nanoparticles (MNPs) affecting magnetic field uniformity is studied in this work. The spatial distribution of MNPs in liquid is simulated based on Monte Carlo method. The induced field of the single MNP is combined with the magnetic field distribution of magnetofluid. In the simulation, magnetic field uniformity is described by a statistical distribution. As the chemical shift (CS) and full width at half maximum (FWHM) of magnetic resonance (MR) spectrum can reflect the uniformity of magnetic field, the simulation is verified by spectrum experiment. Simulation and measurement results prove that the CS and FWHM of the MR spectrum are basically positively correlated with the concentration of MNPs and negatively correlated with the temperature. The research results can explain how MNPs play a role in MR by affecting the uniform magnetic field, which is of great significance in improving the temperature measurement accuracy of magnetic nanothermometers and the spatial resolution of magnetic particle imaging.

TranSMS: Transformers for Super-Resolution Calibration in Magnetic Particle Imaging.

Magnetic particle imaging (MPI) offers exceptional contrast for magnetic nanoparticles (MNP) at high spatio-temporal resolution. A common procedure in MPI starts with a calibration scan to measure the system matrix (SM), which is then used to set up an inverse problem to reconstruct images of the MNP distribution during subsequent scans. This calibration enables the reconstruction to sensitively account for various system imperfections. Yet time-consuming SM measurements have to be repeated under notable changes in system properties. Here, we introduce a novel deep learning approach for accelerated MPI calibration based on Transformers for SM super-resolution (TranSMS). Low-resolution SM measurements are performed using large MNP samples for improved signal-to-noise ratio efficiency, and the high-resolution SM is super-resolved via model-based deep learning. TranSMS leverages a vision transformer module to capture contextual relationships in low-resolution input images, a dense convolutional module for localizing high-resolution image features, and a data-consistency module to ensure measurement fidelity. Demonstrations on simulated and experimental data indicate that TranSMS significantly improves SM recovery and MPI reconstruction for up to 64-fold acceleration in two-dimensional imaging.

Developing magnetorelaxometry imaging for human applications

Objective. Magnetic nanoparticles (MNPs) are a promising tool in biomedical applications such as cancer therapy and diagnosis, where localization and quantification of MNP distributions are often mandatory. This can be obtained by magnetorelaxometry imaging (MRXI). Approach. In this work, the capability of MRXI for quantitative imaging of MNP inside larger volumes such as a human head is investigated. We developed a human head phantom simulating a glioblastoma multiforme (GBM) tumor containing MNP for magnetic hyperthermia treatment. The sensitivity of our MRXI setup for detection of MNP concentrations in the range of 3–19 mg cm−3 was studied. Main result. The results show the high capability of MRXI to detect MNPs in a human head sized volume. Superficial sources with a concentration larger than 12 mg cm-3 could be reconstructed with a resulotion of about 1 cm-3. Significance. The reconstruction of the MNP distribution, mimicking a GBM tumor of 7 cm3 volume with clinically relevant iron concentration, demonstrates the in vivo feasibility of MRXI in humans.

Tailored cancer therapy by magnetic nanoparticle hyperthermia: A virtual scenario simulation method

Background and objectiveHyperthermia is a cancer treatment aiming to induce cell death by directly warming cancerous tissues above 40 °C. This technique can be applied both individually and together with other cancer therapies. The main challenge for researchers and medics is to heat only tumoral cells avoiding global or localized heating of sane tissues. The objective in this study is to provide a realistic virtual scenario to develop an optimized multi-site injection plan for tailored magnetic nanoparticle-mediated hyperthermia applications. MethodsA three-dimensional model of a cat's back was tested in three different simulation scenarios, showing the impact of magnetic nanoparticles in each specific environment configuration. ResultsAs a result of this study. This simulation method can, minimising the affection to healthy tissue. ConclusionsThis virtual method will help real and personalized therapy planning and tailor the dose and distribution of magnetic nanoparticles for an enhanced hyperthermia cancer treatment.

Quantitative imaging of magnetic nanoparticles in an unshielded environment using a large AC susceptibility array

BackgroundNon-invasive magnetic imaging techniques are necessary to assist magnetic nanoparticles in biomedical applications, mainly detecting their distribution inside the body. In Alternating Current Biosusceptometry (ACB), the magnetic nanoparticle's magnetization response under an oscillating magnetic field, which is applied through an excitation coil, is detected with a balanced detection coil system.ResultsWe built a Multi-Channel ACB system (MC-ACB) containing nineteen pick-up coils and obtained 2D quantitative images of magnetic nanoparticle distributions by solving an inverse problem. We reconstructed the magnetic nanoparticles spatial distributions in a field of view of 14 × 14 cm2 with a spatial resolution of 2.0 cm and sensitivity in the milligram scale. A correlation coefficient between quantitative reconstructed and nominal magnetic nanoparticle distributions above 0.6 was found for all measurements.ConclusionBesides other interesting features such as sufficient large field of view dimension for mice and rat studies, portability, and the ability to assess the quantitative magnetic nanoparticles distributions in real-time, the MC-ACB system is a promising tool for quantitative imaging of magnetic nanoparticles distributions in real-time, offering an affordable setup for easy access in clinical or laboratory environments.

Inverse problem of magneto-acoustic concentration tomography for magnetic nanoparticles with magnetic induction in a saturation magnetization state based on the least squares QR factorization method-trapezoidal method.

In order to improve the imaging quality of magneto-acoustic concentration tomography for magnetic nanoparticles (MNPs) with magnetic induction (MACT-MI) and overcome the boundary singularity, this paper built a matrix model which shows the relationship between the partial derivative distribution of MNP concentration and the ultrasound signals, and focused on proposing a concentration reconstruction method based on the least squares QR factorization (LSQR) method-trapezoidal method. Firstly, simulation models with different shapes were established. Secondly, the magnetic and acoustic field simulation data was substituted into the inverse problem method based on LSQR-trapezoidal method for concentration reconstruction. Finally, the reconstructed images were analyzed and the effect of MNP cluster radius on the reconstruction was investigated. Considering the diffusely asymptotic concentration distribution of MNPs in actual biological tissue environment, an asymptotic concentration model was established and the reconstructed images were analyzed. The simulation results show that under the same conditions, compared with the reconstruction method based on the method of moments (MoM), LSQR-trapezoidal method has clearer image boundaries, more stable imaging results, and faster imaging speed. Compared with the uniform concentration model, LSQR-trapezoidal method is more applicable to the asymptotic concentration model. This study provides a basis for further reconstruction of the accuracy of experimental research.

Magnetic poly(ε-caprolactone)-based nanocomposite membranes for bone cell engineering

Magnetic polymer nanocomposites manipulatable by an external magnetic field have a great potential for bone tissue regeneration. Various strategies have been proposed for their fabrication, as uniform distribution of magnetic nanoparticles (MNPs) within the polymer matrix remains to be the main challenge. The aim of this study was to design poly(ε-caprolactone) (PCL) matrix containing iron oxide nanoparticles stabilized by saturated fatty acids with the increasing number of carbon atoms, i.e., caprylic (CA), palmitic (PA), and stearic acids (SA). We investigated the effect of the type of fatty acid and the content of particles in nanocomposite membranes on their physicochemical properties and biological response toward the SAOS-2 cells. The incorporation of the MNPs in PCL matrix resulted in a gradual increase of Young’s modulus, a slight decrease of tensile strength, and a significant decrease of stress and strain at break. The addition of SA-stabilized MNPs (1 wt%) in the PCL matrix increased its strength. The membranes containing CA-stabilized MNPs remained non-toxic towards SAOS-2 cells, while the cytotoxicity of other nanocomposites increased with the enhanced length of carbon chains of fatty acids stabilizing MNPs, as well as with their increasing content in membranes.

Biodistribution Profile of Magnetic Nanoparticles in Cirrhosis-Associated Hepatocarcinogenesis in Rats by AC Biosusceptometry

Since magnetic nanoparticles (MNPs) have been used as multifunctional probes to diagnose and treat liver diseases in recent years, this study aimed to assess how the condition of cirrhosis-associated hepatocarcinogenesis alters the biodistribution of hepatic MNPs. Using a real-time image acquisition approach, the distribution profile of MNPs after intravenous administration was monitored using an AC biosusceptometry (ACB) assay. We assessed the biodistribution profile based on the ACB images obtained through selected regions of interest (ROIs) in the heart and liver position according to the anatomical references previously selected. The signals obtained allowed for the quantification of pharmacokinetic parameters, indicating that the uptake of hepatic MNPs is compromised during liver cirrhosis, since scar tissue reduces blood flow through the liver and slows its processing function. Since liver monocytes/macrophages remained constant during the cirrhotic stage, the increased intrahepatic vascular resistance associated with impaired hepatic sinusoidal circulation was considered the potential reason for the change in the distribution of MNPs.