Specific Absorption Rate Research Articles

Evaluation and SAR Analysis of Low Frequency and Broadband Electric Field Exposure Measurement Values in the Home Environment

In this study, the effective value of low-frequency (50 Hz) and high-frequency (700–2500 MHz) broadband electric field exposures was measured for 24 h in four different selected environments in a house. All the statistical values of 1000 data points recorded with two measuring devices for 24 h in each environment are calculated, the most appropriate curves are fitted to the data, and the curves are plotted by expressing their changes with respect to time. All statistical and parametric values of the density and cumulative probability functions of the curves are calculated and plotted. In broadband measurements, the broadband is divided into fifteen sub-bands, but the data are available in only six of these sub-bands. The six-layer human head model is created by using the middle frequencies of the six sub-bands used, and taking the permittivity (εr) and conductivity (σ) of each layer into consideration. The specific absorption rate (SAR) value in the brain is calculated by using the total transmission coefficient of six layers. The SAR value surrounding the head is obtained. These SAR values are interpreted by considering the Federal Communications Commission (FCC) and the Community European (CE) occupational and general public SAR limits.

Trust region framework-based design of sub-6 GHz m-MIMO antenna and evaluation of SAR

PurposeCurrently, massive multiple-input multiple-output (m-MIMO) antennas are typically designed using complex trial-and-error methods. The purpose of this study is to determine an effective optimization method to achieve more efficient antenna design processes.Design/methodology/approachThis paper presents the design stages of a m-MIMO antenna array compatible with 5G smartphones operating in long term evolution (LTE) bands 42, 43 and 46, based on a specific algorithm. Each antenna element in the designed 10-port m-MIMO antenna array is intended to perfectly cover the three specified LTE bands. The optimization methods used for this purpose include the Nelder–Mead simplex algorithm, covariance matrix adaptation evolution strategy, particle swarm optimization and trust region framework (TRF).FindingsAmong the primary optimization algorithms, the TRF algorithm met the defined objectives most effectively. The achieved antenna efficiency values exceeded 60.81% in the low band and 68.39% in the high band, along with perfect coverage of the desired bands, demonstrating the success of the design with the TRF algorithm. In addition, the potential electromagnetic field exposure caused by the designed m-MIMO antenna array is elaborated upon in detail using computational human models through specific absorption rate analysis.Originality/valueThe comparison of four different algorithms (two local and two global) for use in the design of a 10-element m-MIMO antenna array with a complex structural configuration and the success of the design implemented with the selected algorithm distinguish this study from others.

Effects of non-ionizing radio frequency electromagnetic radiation on the development and behavior of early embryos of Danio rerio

ABSTRACT Biological effects of radio frequency electromagnetic radiation (RF-EMR) in the range of 900–1800 MHz emerging from the mobile phone were investigated and were found to influence the locomotor pattern when exposure was initiated from 1 hour post fertilization (hpf) in zebrafish embryos (ZE), Danio rerio. Mobile phones and other wireless devices offer tremendous advantages. However, on the flipside they are leading to an increased electromagnetic energy in the environment, an excess of which could be termed as electromagnetic pollution. Herein, we tried to understand the effects of RF-EMR emerging from the mobile phone, on the development and behavior of ZE, exposed to RF-EMR (specific absorption rate of 1.13 W/kg and 1800 MHz frequency) 1 hr daily, for 5 days. To understand if there could be any developmental stage-specific vulnerability to RF-EMR, the exposure was initiated at three different time points: 1hpf, 6hpf and 24hpf of ZE development. Observations revealed no significant changes in the survival rate, morphology, oxidative stress or cortisol levels. However, statistically significant variations were observed in the batch where exposure started at 1hpf, with respect to locomotion patterns (distance travelled: 659.1 ± 173.1 mm Vs 963.5 ± 200.4 mm), which could be correlated to anxiety-like behavior; along with a corresponding increase in yolk consumption (yolk sac area: 0.251 ± 0.019 mm2 Vs 0.225 ± 0.018 mm2). Therefore, we conclude that RF-EMR exposure influences the organism maximally during the earliest stage of development, and we also believe that an increase in the time of exposure (corresponding to the patterns of current usage of mobile phones) might reveal added afflictions.

Economic and Accessible Portable Homemade Magnetic Hyperthermia System: Influence of the Shape, Characteristics and Type of Nanoparticles in Its Effectiveness.

Currently, one of the main causes of death in the world is cancer; therefore, it is urgent to obtain a precocious diagnosis, as well as boost research and development of new potential treatments, which should be more efficient and much less invasive for the patient. Magnetic hyperthermia (MH) is an emerging cancer therapy using nanoparticles, which has proved to be effective when combined with chemotherapy, radiotherapy and/or surgery, or even by itself, depending on the type and location of the tumor's cells. This article presents the results obtained by using a previously developed economic homemade hyperthermia device with different types of magnetite nanoparticles, with sizes ranging between 12 ± 5 and 36 ± 11 nm and presenting different shapes (spherical and cubic particles). These magnetic nanoparticles (MNPs) were synthesized by three different methods (co-precipitation, solvothermal and hydrothermal processes), with their final form being naked, or possessing different kinds of covering layers (polyethylene glycol (PEG) or citric acid (CA)). The parameters used to characterize the heating by magnetic hyperthermia, namely the Specific Absorption Rate (SAR) and the intrinsic loss power (ILP), have been obtained by two different methods. Among other results, these experiments allowed for the determination of which synthesized MNPs showed the best performance concerning hyperthermia. From the results, it may be concluded that, as expected, the shape of MNPs is an important factor, as well as the time that the MNPs can remain suspended in solution (which is directly related to the concentration and covering layer of the MNPs). The MNPs that gave the best results in terms of the SAR were the cubic particles covered with PEG, while in terms of total heating the spherical particles covered with citric acid proved to be better.

Design of a mid-field wireless power transmission system for deep-tissue implants.

Implantable medical devices are being valued as one of the developments of wireless biomedical technology. This paper presents a mid-field wireless power transmission (WPT) system, which is designed for implantable applications and operates at the 2.40-2.48 GHz band of Industrial, Scientific, and Medical (ISM). A new compact transmitter structure is proposed, and a small 4-C planar ring antenna is designed as the receiving element. A measurement setup is fulfilled on porcine tissues to verify the power transmission system. The experimental results show that the operating bandwidth is 2.2-2.62 GHz and the transmission coefficient can reach -26.32 dB at a distance of 50 mm. The effects of tissue differences, placement depth, and different transmission distances were also measured. The displacement and deflection tolerances between the transmitter and the implant receiver also have good performance. In the safety standard of specific absorption rate, for the 1 W output power from the mid-field transmitter, the receiving power of the implantable antenna at the mid-field distance can reach 79.6 mW. With measurements of different implantation and transmission distance on pork, the mid-field power transmission efficiency is proven and shows the high performance of the system.

Whole-body SAR measurements of millimeter-wave base station in reverberation chambers

Abstract This paper presents a method for measuring whole-body specific absorption rate (WBSAR) of millimeter-wave base stations (BSs) in a reverberation chamber (RC). The absorbed power in the phantom from the equipment under test (EUT) and hence WBSAR is determined as the difference between the total radiated power with and without the phantom. A chamber transfer function is determined and used to include only the absorption in the phantom due to direct illumination from the EUT, i.e., excluding absorption due to the RC multipath reflections. The measurement method was evaluated at 28 GHz using a horn antenna and a commercial massive multi-input–multi-output BS. The experimental results are in good agreement with simulations. The proposed method allows for measurements of WBSAR within 3 minutes, which is much shorter than traditional approaches. The method is suitable for compliance assessments of BS products with the International Commission on Non-Ionizing Radiation Protection 2020 electromagnetic field exposure guidelines, which extend the applicability of WBSAR as basic restrictions up to 300 GHz.

1.7 GHz long-term evolution radiofrequency electromagnetic field with stable power monitoring and efficient thermal control has no effect on the proliferation of various human cell types.

Long-term evolution (LTE) radiofrequency electromagnetic field (RF-EMF) is widely used in communication technologies. Thus, the influence of RF-EMF on biological systems is a major public concern and its physiological effects remain controversial. In our previous study, we showed that continuous exposure of various human cell types to 1.7 GHz LTE RF-EMF at a specific absorption rate (SAR) of 2 W/Kg for 72 h can induce cellular senescence. To understand the precise cellular effects of LTE RF-EMF, we elaborated the 1.7 GHz RF-EMF cell exposure system used in the previous study by replacing the RF signal generator and developing a software-based feedback system to improve the exposure power stability. This refinement of the 1.7 GHz LTE RF-EMF generator facilitated the automatic regulation of RF-EMF exposure, maintaining target power levels within a 3% range and a constant temperature even during the 72-h-exposure period. With the improved experimental setup, we examined the effect of continuous exposure to 1.7 GHz LTE RF-EMF at up to SAR of 8 W/Kg in human adipose tissue-derived stem cells (ASCs), Huh7, HeLa, and rat B103 cells. Surprisingly, the proliferation of all cell types, which displayed different growth rates, did not change significantly compared with that of the unexposed controls. Also, neither DNA damage nor cell cycle perturbation was observed in the 1.7 GHz LTE RF-EMF-exposed cells. However, when the thermal control system was turned off and the subsequent temperature increase induced by the RF-EMF was not controlled during continuous exposure to SAR of 8 W/Kg LTE RF-EMF, cellular proliferation increased by 35.2% at the maximum. These observations strongly suggest that the cellular effects attributed to 1.7 GHz LTE RF-EMF exposure are primarily due to the induced thermal changes rather than the RF-EMF exposure itself.

The effect of exposure to RF-EMF from the laboratory simulator of 5G NR base station on physiological parameters and cognitive abilities of male wistar rats of different ages

In this article, the impact of radiofrequency electromagnetic field (RF-EMF) exposure from a simulated base station for the 5G New Radio (5G NR) telecommunication on rats was studied. The base station affects all age groups of the population, thus, for the first time, the experiment was conducted on male Wistar rats of three different ages (juvenile, adult, and presenile). The base station exposure parameters were chosen according to ICNIRP recommendations for limiting the exposure to radiofrequency electromagnetic field: frequency 2.4 GHz with an average specific absorption rate of 0.0076 W/kg and 0.0059 W/kg over the whole body of experimental animals. Throughout the experiment, body weight was examined weekly, and the dynamics of body weight gain was monitored. Rectal and skin surface temperature on the right hind limb was monitored weekly. Testing in the Morris water maze was performed during the last, Week 5, of RF-EMF exposure. After euthanasia, organ weights were determined in experimental and control animals. None of the investigated parameters did show any statistically significant differences between exposed and control animals of the same age. The data obtained can be used to assess the possible consequences of chronic exposure to RF-EMF from 5G NR base stations.

Absorption of 5G sub-6 GHz electromagnetic radiation from base station to male reproduction system

Background The impact of electromagnetic radiation from communication on the male reproductive system has emerged as a significant concern in public health. A notable distinction of the 5G sub-6 GHz band, compared to traditional 2G, 3G, and 4G frequency bands, is the inclusion of higher frequency bands. This has raised public concerns regarding the potential effects of these higher frequencies on organisms, particularly their reproductive systems. While it is imperative to investigate the biological effects and potential risks associated with these new frequency bands in laboratory settings, comparing and evaluating differences between various frequency bands remain challenging due to the absence of standardized parameters such as exposure conditions and duration. In contrast, dose assessment offers a simpler and more reliable approach. Materials and methods The dose assessment method was employed in this study to investigate the risks associated with sub-6 GHz electromagnetic radiation from 5G base stations on the male reproductive system. A classical human body model (Duke) was utilized, and an electromagnetic simulation environment was established based on the actual polarization direction of the exposed base stations and various body postures. This research explored the effects of field direction, posture, public population, and frequency on the specific absorption rate of the reproductive system. Results and conclusions While maintaining the same level of exposure, a higher frequency results in a reduced dosage on reproductive system. Further analysis reveals that, considering the public exposure threshold, the employment of higher frequency bands in 5G sub-6 GHz does not present a greater dosage on reproductive system compared to lower frequency bands. Consequently, with regard to dosage, there is no need for excessive concern among the general public regarding the impact of electromagnetic radiation emitted by 5G base stations operating below 6 GHz on male reproductive health.

Effect of moringa oleifera with pure and Zn-doped Mn and Ni nanoferrites for hyperthermia applications

Nanoferrites like spinel manganese ferrite (MnFe2O4) and inverse spinel nickel ferrite (NiFe2O4) have an efficient heating deportment to the destruction of neoplasm. The incorporation of Moringa oleifera (MO) leaf extracts with magnetic nanoparticles as heat mediators is an effective approach for treating magnetic hyperthermia. This study investigated the potential heating behavior of bare, Zn-doped MnFe2O4 and NiFe2O4 nanoparticles (NPs) with Moringa oleifera leaf extracts as magnetic hyperthermia agents. High-resolution transmission electron microscopy showed the spherical-like morphology of MnFe2O4 NPs with no impurities in the EDX spectra. X-ray diffraction spectra confirmed the cubic spinel and inverse spinel structure for MnFe2O4 and NiFe2O4 NPs, respectively. Magnetic properties of the prepared nanoferrites exhibit low coercivity values (in the range of 13–18 Oe representing superparamagnetic behavior. Further, the binding energies of the prepared nanoferrites were revealed by X-ray photoelectron spectroscopy. The effective magnetic anisotropy constant (Keff) was calculated to be around 3.9–5.9 kJ/m3 by electron spin resonance. An increased specific surface area (120.69 m2/g) and wider porosity (17.053 nm) were observed for MnFe2O4/MO NPs through Brunauer-Emmett-Teller (BET) analysis. Thermal properties were investigated by measuring the effective specific absorption rate in an alternating magnetic field ranging from 23 to 31 * 10−9 W/g Oe2 Hz. Results indicated that the green synthesized MnFe2O4/MO NPs are promising agents for magnetic hyperthermia applications in cancer therapy.

Chemical and physical modification of graphene oxide nano-sheets using casein, Zn-Al layered double hydroxide, alginate hydrogel, and magnetic nanoparticles for biomedical applications

In our study, we developed a novel nanobiocomposite using graphene oxide (GO), casein (Cas), ZnAl layered double hydroxide (LDH), sodium alginate (Alg), and Fe3O4 magnetic nanoparticles. To synthesize the GO, we used a modified Hummer's method and then covalently functionalized its surface with Cas protein. The functionalized GO was combined with as-synthesized ZnAl LDH, and the composite was conjugated with alginate hydrogel through the gelation process. Finally, we magnetized the nanobiocomposite using in-situ magnetization. The nanobiocomposite was comprehensively characterized using FT-IR, FE-SEM, EDX, and XRD. Its biological potential was assessed through cell viability, hemolysis, and anti-biofilm assays, as well as its application in hyperthermia. The MTT assay showed high cell viability percentages for Hu02 cells after 24, 48, and 72 h of incubation. The nanobiocomposite had a hemolytic effect lower than 3.84 %, and the measured bacterial growth inhibition percentages of E. coli and S. aureus bacteria in the presence of the nanobiocomposite were 52.18 % and 55.72 %, respectively. At a concentration of 1 mg.mL−1 and a frequency of 400 kHz, the nanocomposite exhibits a remarkable specific absorption rate (SAR) of 67.04 W.g−1, showcasing its promising prospects in hyperthermia applications.

An efficient wireless power transfer system planar turn based for implantable medical devices applications

A wireless power transfer system based on inductive coupling for powering implantable medical devices of diverse application is proposed. The system is composed of two resonators based with circular spiral printed on a dielectric substrate. With operation corresponding to the frequency range of medical applications in implants of 403 MHz, and an RF power transfer efficiency (PTE) greater than 50.0 % is obtained with a total reach of 8.0 mm into living tissue. Numerical studies and analyses are carried out in order to investigate the influence of tissues on the frequency response and efficiency of the presented resonators. Through simulations it is possible to establish the maximum input power limit of 120.0 mW of the model to comply with the safety limits of the specific absorption rate (SAR) below 2.0 W/kg. In general, the simulated and measured results demonstrate a good level of agreement. Comparative analyses and conclusions are presented and discussed.

Assessment of local temperature elevation at the surface of tissue exposed to radiation of milimeter waves using simplified analytical approach

Dominant effect of human exposure to electromagnetic fields in GHz frequency range corresponding to operation of 5G mobile communications systems is tissue heating i.e. local temperature elevation at the body surface, i.e. skin, ear and eyes. For the frequencies below transition frequency of 6GHz specific absorption rate (SAR) is used to quantify the volume heating. On the other hand, the surface heating above 6GHz is quantified via absorbed power density (Sab ). Once these quantities are determined by means of internal field dosimetry procedures it is possible to determine the local surface temperature increase by solving the bio-heat transfer equation. The present paper deals with the calculation of tissue surface heating due to exposure to millimeter waves. Internal dosimetry is based on the planar tissue model exposed to dipole antenna radiation. Electromagnetic model is based on the analytical solution of Pocklington integro-differential equation while the assessment of tissue surface heating in planar tissue model has been carried by analytically solving a simplified variant of the bio-heat transfer equation. Some illustrative results for power density and temperature elevations will be presented for different antenna parameters.

Effect of surgical modification of deep brain stimulation lead trajectories on radiofrequency heating during MRI at 3T: from phantom experiments to clinical implementation.

Radiofrequency (RF) tissue heating around deep brain stimulation (DBS) leads is a well-known safety risk during MRI, resulting in strict imaging guidelines and limited allowable protocols. The implanted lead's trajectory and orientation with respect to the MRI electric fields contribute to variations in the magnitude of RF heating across patients. Currently, there are no surgical requirements for implanting the extracranial portion of the DBS lead, resulting in substantial variations in clinical lead trajectories and consequently RF heating. Recent studies have shown that incorporating concentric loops in the extracranial lead trajectory can reduce RF heating. However, optimal positioning of the loops and the quantitative benefit of trajectory modification in terms of added safety margins during MRI remain unknown. In this study, the authors systematically evaluated the characteristics of DBS lead trajectories that minimize RF heating during 3T MRI to develop the best surgical practices for safe access to postoperative MRI, and they present the first surgical implementation of these modified trajectories. The authors performed experiments to assess the maximum temperature increase of 244 distinct lead trajectories. They investigated the effect of the position, number, and size of the concentric loops on the skull. Experiments were performed in an anthropomorphic phantom implanted with a commercial DBS system, and RF exposure was generated by applying a high specific absorption rate sequence (B1+rms = 2.7 µT). The authors conducted test-retest experiments to assess the reliability of measurements. Additionally, they evaluated the effect of imaging landmarks and perturbations to the DBS device configuration on the efficacy of low-heating trajectories. Finally, two neurosurgeons implanted the recommended modified trajectories in patients, and the authors characterized their RF heating in comparison with unmodified trajectories. The maximum temperature increase ranged from 0.09°C to 7.34°C. The authors found that increasing the number of loops and positioning them closer to the surgical burr hole, particularly for the contralateral lead, substantially reduced RF heating. These trajectory modifications were easily incorporated during the surgical procedure and resulted in a threefold reduction in RF heating. Surgically modifying the extracranial portion of the DBS lead trajectory can substantially reduce RF heating during 3T MRI. The authors' results indicate that simple adjustments to the lead's configuration, such as small, concentric loops near the burr hole, can be readily adopted during DBS lead implantation to improve patient safety during MRI.

Design of a Compact Wearable Antenna for IoT Enabled Bio-Telemetry in Diagnostic Health Monitoring System

The structure developed involves the etching of Moore’s curve onto a conventional rectangular patch and subsequently encasing it in a rectangular loop along with a defected ground structure. The proposed antenna exhibits dual-band Since the Internet of Things (IoT) enabled medical diagnostic system requires unprecedented precision and automation for better health care delivery, therefore in such systems, the performance of antennas for efficiently transferring data (vital functions of the human body) is an important task. To address these concerns, a mechanically robust, novel hybrid wearable on-body antenna inspired by Moore’s fractal based geometry and conventional rectangular loop for a diagnostic health monitoring system is proposed. with bandwidth ranging from 1.38 - 1.8 GHz and 2.25 - 4.88 GHz respectively, covering WMTS, ISM, and Personal Communication band besides covering a portion of UWB band also. The two operating bands of the antenna offer a fractional bandwidth of 38.5% and 73.7% respectively. It is observed that the average specific absorption rate (SAR) over the multi-layer phantom is 0.025 W/kg for an input power of ≈ 24 dBm. In comparison to the recently reported wearable antennas, the design proposed has a compact footprint of 0.135 λo x 0.093λo x 0.004λo besides offering a dual- band of operation, peak gain of 2.2 dBi, overall radiated efficiency of 95% and SAR below 0.025 W/kg. The design is fabricated using Rogers 5880 substrate (semi-flex) of thickness 0.75 mm.

Enhanced Circularly Polarized Antenna for Body Centric Communication

Abstract: This study introduces a miniaturized circularly polarized ultra-wideband (UWB) antenna designed specifically for body-centric communication applications, with a focus on its performance across different frequencies. Fabricated on jean fabric, the antenna offers exceptional flexibility and seamless integration into clothing, making it ideal for wearable devices. The design achieves circular polarization through the utilization of an asymmetric stepped L-shaped ground plane and a crossshaped stub integrated into the radiator structure.Operating across the UWB frequency spectrum ranging from 3 GHz to 9.5 GHz, the antenna exhibits consistent and reliable performance in terms of gain, radiation pattern, and current distribution. ensuring effective signal transmission and reception. Importantly, the antenna complies with FCC specific absorption rate (SAR) limits, ensuring safety in wearable applications.Throughout the frequency range, the antenna maintains an omnidirectional radiation pattern, facilitating reliable on-body communication regardless of orientation. This characteristic is crucial for maintaining connectivity and signal quality in body-centric communication systems.Analysis of the current distribution confirms the antenna's effectiveness across different frequency bands, further validating its performance and suitability for body-centric communication applications.

Study on the influencing factors of impact resistance of shear thickening fluids filled foam

PurposeThe present study assesses the impact resistance of the shear thickening fluids-filled (STFs-filled) foam through drop-hammer impact tests.Design/methodology/approachThe maximum residual impact load and specific impact energy absorption rate of STF-filled foam are studied with varying thickness (4–14 mm), densities (0.35–0.6 g/cm3) and hardness (40–50 Rockwell Hardness C Scale (HRC)) under different ambient temperatures (−20−20 °C) and impact energies (25–75 J).FindingsThe following conclusions are obtained from this study: (1) the higher the impact energy, the greater the maximum residual impact force and energy absorption efficiency of the material; (2) the impact resistance of STF-filled foam can be improved with the decrease of ambient temperature, achieving the highest energy absorption rate at −10?. (3) STF-filled foam substrate has the highest impact resistance, the lowest maximum residual impact force and the highest energy absorption coefficient when the density is 0.35 g/cm3, the hardness is 45HC and the thickness is 10 mm.Originality/valueThis is the first paper to analyze the impact of both environmental factors and material properties on the impact resistance of STF-filled foam. The results show that the decrease in temperature and the increase in hardness can enhance the impact resistance of STF-filled foam.

Safety Assessment of Electromagnetic Environmental Exposure for GPS Antenna of Electric Vehicle

The present GPS (global positioning system) is widely used in electric vehicle navigation; it is usually installed in the middle-to-rear position on the car’s roof, near the rear windshield. Since the GPS antenna operating frequency is 1.575 GHz, the health risk of the passengers in the car in this high-frequency electromagnetic exposure is a matter of concern. In this paper, we construct models for a GPS antenna, an electric vehicle, and a human body. Through the multiphysics field coupling calculation in COMSOL Multiphysics, a finite element simulation software, in both frequency domain and transient analysis, we obtain the electric field strength distribution, specific absorption rate, and temperature distribution of the human body at three positions inside the electric vehicle after being exposed to the GPS antenna radiation for 30 minutes. The peak human-induced electric field is 18.4 V/m, and the peak specific absorption rate is 0.193 W/kg. The 30 minute average maximum human-induced electric field is 1.6906 V/m, which is 3.1% of the ICNIRP limit, the 30 minute average whole-body SAR is 0.0036 W/kg, which is 4.5% of the ICNIRP limit, and the 30 minute average human core temperature rise is 0.06°C, which is 6% of the ICNIRP limit. In addition, we simulate the impact of three different vehicle shell materials on the level of electromagnetic exposure to the human body, which can provide reference for electromagnetic shielding design in automobiles. The results indicate that the induced electric field strength, specific absorption rate (SAR), and temperature rise in various parts of the human body did not exceed the standard limits in the latest version of ICNIRP. This suggests that the electromagnetic exposure from the GPS antenna in a typical automotive environment does not pose a threat to human health.

Synthesis, physico-chemical properties, and AC induction heating of polycaprolactone-coated bio-compatible Fe3O4 nanoparticles

Ex-situ functionalization of Fe3O4 nanoparticles, synthesized using a coprecipitation method, with bio-compatible polycaprolactone (PCL) polymer is reported in this study. The formation of the crystalline structure of Fe3O4 is confirmed from the X-ray diffraction patterns. The presence of the PCL polymer on the surface of the coated MNPs is confirmed using Fourier transform infrared and X-ray photoelectron spectroscopy techniques and thermogravimetric analysis. Scanning and transmission electron microscopy imaging studies reveal the nearly spherical morphology of the synthesized nanoparticles. Room temperature magnetization measurements show the superparamagnetic nature of the PCL coated nanoparticles with high saturation magnetizations varying from ∼61–66 emu/g. Further, the room temperature coercivity is found to be reduced by ∼78 % for the PCL coated nanoparticles, which is attributed to the lowering of the interparticle interactions upon surface functionalization. Magnetic fluid hyperthermia studies on the PCL coated nanoparticles dispersed in ∼1 wt% agar gel shows significant alternating magnetic field induced heating efficiency, with temperature rise in the vicinity of the hyperthermia limit (∼42 °C). The highest specific absorption rate is found to be ∼85.4 ± 3.9 W/gFe, indicating an intrinsic loss power of ∼0.62 nHm2kg−1, which is significantly higher than the previously reported values for PCL coated Fe3O4 MNPs. The field induced heating efficiency is found to be correlated with the saturation magnetization of the PCL coated nanoparticles. In vitro cytotoxicity studies on human breast cancer (MCF-7) cell lines confirm the superior bio-compatibility of the PCL coated Fe3O4 nanoparticles. Superior field induced heating efficiency, coupled with good bio-compatibility makes the PCL functionalized Fe3O4 nanoparticles a potential candidate for magnetic fluid hyperthermia.

Superparamagnetic iron oxide nanoparticles functionalized by biocompatible ligands with enhanced high specific absorption rate for magnetic hyperthermia

This study introduces a novel green nanocomposite system of iron oxide coated with secondary metabolites (Fe3O4@SM) and compares it with commonly used materials for hyperthermia cancer treatment. Fe3O4@SM magnetic nanoparticles were synthesized through a simple co-precipitation process using metal precursors, followed by heating in pressure reactor to obtain superparamagnetic nanoparticles (Hc = 36.5–54.1 Oe at 300 K). These nanoparticles were subsequently coated with plant-based phytochemicals. XRD analysis confirmed the presence of magnetite iron oxide nanoparticles. SEM images further confirmed the spherical shape of the synthesized nanoparticles, exhibiting a face-centered cubic (FCC) iron oxide structure with sizes ranging from 12±7–85±15 nm. Characterization through dynamic light scattering (DLS) and zeta potential (ζ) analysis demonstrated colloidal stability, with a polydispersity index (PDI) ranging from 0.226 to 0.436 and zeta potential values ranging from −29.761–1.85 mV. The surface of the nanoparticles was analyzed using GC-MS, which identified bioactive functional groups including ester (42.79 %), terpene (20.69 %), hydrocarbons (17.4 %), and carboxylic (12.37 %) compounds. Compared to Fe3O4 and Fe3O4@GO, Fe3O4@SM exhibited a higher rate of temperature increase within the therapeutic range, reaching Tmax = 45°C with a heating rate (dT/dt) of 0.273 °C/s and specific absorption rate (SAR) of 230.6 W/g at 304 kHz and 400 Oe. In vitro assays utilizing a triple negative breast cancer microenvironment confirmed the non-toxicity of these materials through a DNS assay. The developed nanoparticles offer dual mechanisms of action, combining thermal and chemo effects, making them promising candidates for hyperthermia cancer treatment.