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This study presents a significant advancement in cancer therapy through the application of Mn-substituted magnetite superparamagnetic (SPM) nanoparticles, highlighting the potential of magnetic fluid hyperthermia (MFH) as an effective modality. However, its clinical applications have been limited by challenges such as low heating performance, agglomeration of magnetic nanoparticles (MNPs) in blood veins, and cytotoxicity. To address these crucial issues, surface engineered MNPs were synthesised by adopting a reverse micelles-based co-precipitation approach that effectively overcomes MNP agglomeration, ensuring uniform dispersion of the nanoparticles. Through careful optimization of Mn ion substitution within magnetite, we have achieved a significant enhancement in the heating performance of the magnetite SPM nanoparticles. The substitution of Mn2+ ions in magnetite has notably increased the specific absorption rate (SAR) value, as evidenced by a remarkable 181% increase (SAR: 510 kW/kg) obtained using the Box Lucas Method. This enhancement can be attributed to the elevated saturation magnetization resulting from the appropriate cation distribution within the MNPs. Furthermore, the increase in spin relaxation time with higher Mn concentration also contributes to the improvement in SAR values as MNPs retain their magnetic moments for an extended period before relaxing, leading to enhanced energy dissipation and higher SAR values. The hemolysis assays demonstrated minimal hemolysis rates (<5%) when exposed to red blood cells (RBCs), confirming the high biocompatibility of the MNPs. Additionally, MTT assays revealed excellent cytocompatibility (>90% cell viability) for Human Embryonic Kidney (HEK-293) cells across all compositions, further affirming the potential of these MNPs for clinical treatments. Overall, this study unveils a sustainable approach for cancer therapy using Mn-substituted magnetite SPM nanoparticles. Their remarkable heating performance and excellent biocompatibility make them promising for clinical applications in MFH. • Significant advancement in MFH for cancer treatment using Mn-substituted magnetite nanoparticles. • Achieved a remarkable 181% increase in specific absorption rate (SAR) for enhanced heating performance. • Overcame challenges of agglomeration through surface engineering and reverse micelles-based co-precipitation. • MNPs demonstrated high biocompatibility with minimal hemolysis rates and excellent cytocompatibility for HEK-293 cells. [ABSTRACT FROM AUTHOR]

Abstract In a new approach based on a two-step procedure, co-precipitation method followed by hydrothermal treatment in a microwave field, Zn-substituted Fe 3 O 4 nanoparticles (Zn x Fe 3- x O 4) were synthesized. Results of XRD, FT–IR and TEM analysis clearly demonstrate that nanoparticles were single phase, crystallizing in the spinel structure type (S.G. Fd 3 ¯ m) with crystallite size in the range of 2–20 nm, which strongly depends on Zn concentration. The produced nanoparticles were used for fabrication of modified carbon paste electrodes as a novel system for electrochemical non-enzymatic glucose detection. It was found that the increase of zinc concentration up to the value of x = 0.56 (Zn 0.56 Fe 2.44 O 4) of as-prepared nanoparticles was followed with an increase of a performance of the modified carbon paste electrode toward glucose detection. Linear working range from 0.1 to 2 mM was obtained with detection limit of 0.03 mM, and with fast response time (<3 s). Proposed sensor was successfully applied for the determination of glucose level in real samples with satisfactory recovery. The synthesized zinc-ferrite samples were also tested as potential heating agents in magnetic hyperthermia. The heating ability (SAR value) increases with x value, reaching maximum for x = 0.37. This is correlated with changes of particle size and magnetic characteristics which strongly depend on Zn concentration. Highlights • Preparation of Zn x Fe 3- x O 4 composite by co-precipitation method in combination with hydrothermal treatment. • Effect of zinc content in ferrite structure was investigated and bifunctionality of the material was shown. • Construction of non-enzymatic glucose biosensor based on substituted magnetite was done. • Promising sensitivity, satisfactory selectivity and simplicity of glucose detection were achieved. • Prepared materials were tested as potential heating agents in magnetic hyperthermia. [ABSTRACT FROM AUTHOR]

This current work deals with the study of the magnetic and biomedical characterization of La 0.7 Sr 0.3 Mn 1-x B x O 3 (B=Mo, Ti) nanoparticles for hyperthermia applications. Our nanoparticles were prepared through an aqueous combustion process (Glycine Nitrate Process, GNP), and are characterized with a mean crystallite size about 18 nm. The incorporation of Ti 4+ and Mo 6+ in Mn-site induced a structural transition from rhombohedral structure with R-3 C space group for La 0.7 Sr 0.3 MnO 3 compound to orthorhombic one with Pnma space group for La 0.7 Sr 0.3 Mn 0.95 Mo 0.05 O 3 and La 0.7 Sr 0.3 Mn 0.95 Ti 0.05 O 3 compounds. The morphological properties indicated a variation in grain size ranging from 82 to 90 nm with doping extra element in manganese site. All samples exhibit a classical behavior from ferromagnetic (FM) to paramagnetic (PM) state as the temperature increases. A decrease in Curie temperature (T C ) has been remarked from 84 °C to 70 °C and 82 °C for La 0.7 Sr 0.3 MnO 3 , La 0.7 Sr 0.3 Mn 0.95 Ti 0.05 O 3 , La 0.7 Sr 0.3 Mn 0.95 Mo 0.05 O 3 respectively. According to the Arrott plots, the slopes of the curves of all the samples are positive, which is a signature of second order transition. The magnetic heating characteristics in AC field were measured in alternating magnetic fields of 23.89 mT at a fixed frequency of 518.7 kHz. The intrinsic loss power (ILP) has been calculated from SAR values. The different nanoparticles with a high ILP may be useful for the in situ hyperthermia treatment of cancer cells. [ABSTRACT FROM AUTHOR]

This paper deals with the influence of a biocompatible surface coating layer on the structural, morphological and colloidal and magnetic properties of the MnZnFe 2 O 4 nanoparticles. A series of the MnZnFe 2 O 4 magnetic nanoparticles were synthesized by simple cost-effective co-precipitation technique. Herein, it is found that starch plays an important role in the colloidal stability, dispersibility and the heating efficiency of MNPs. Samples of the resultant magnetic fluid were examined using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), X-ray diffraction (XRD), transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM), dynamic light scattering, zeta potential measurements, Vibrating sample magnetometry (VSM) and induction heating studies. The average size of the MnZnFe 2 O 4 and MnZnFe 2 O 4 @starch nanoparticles estimated by TEM technique was found to be in the range of 12–15 nm. Magnetometry measurements indicate that superparamagnetic like nature with negligible coercivity and remanence for any of sample. Induction heating efficiency of MnZnFe 2 O 4 nanoparticles under alternating magnetic field was studied by means of specific absorption rate (SAR) measurements, and compared with starch functionalized MnZnFe 2 O 4 nanoparticles. In vitro cytotoxicity on human lung cancer cells studies reveal that tolerable dose rate for MNPs can be significantly high and particles are less toxic in nature. Based on these characterizations of the samples it is suggested that the MnZnFe 2 O 4 ferrites may be a potential candidate for hyperthermia application. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the hyperthermia application of a novel bredigite-magnetite nanocomposite for bone tissue engineering. Magnetite nanoparticles were synthesized by the co-precipitation method and then composited with bredigite powders via a mechanical milling route and subsequent sintering process. Bredigite-Magnetite nanocomposite possessed a homogeneous dispersion of magnetite nanoparticles, which was confirmed by the absence of large aggregates. To evaluate the heat release of the composite nanoparticles, an alternating magnetic (AC) field was applied. The results showed an increase in the temperature, as a result of the increasing magnetite concentration. The sample containing 30 wt.% magnetite particles showed a temperature increase about 27 °C during 50 s. Generally, the present work confirmed that the bredigite-magnetite nanocomposite can be considered as an assuring candidate in hyperthermia applications. [ABSTRACT FROM AUTHOR]

The present study examines the effect of annealing temperature on the structural, electronic and magnetic properties of Co-doped TiO 2 (TCO) nanoparticles (NPs) synthesized by the sol-gel method. X-ray powder diffractograms of TCO NPs annealed at 400, 600 and 800 °C exhibited the monophasic anatase, diphase (anatase and rutile) and monophasic rutile structures respectively. A morphological investigation using high-resolution scanning electron microscopy (HR-SEM) reveals the presence of nanoparticles with diameters ranging from ∼11 to ∼51 nm. The widening and shifting of the most intense E g peak in Raman studies and SEM images of TCO NPs suggest Co incorporation in the TiO 2 matrix and the formation of oxygen vacancies. Magnetic measurements of TCO at room temperature demonstrate ferromagnetic behaviour which is caused by the existence of oxygen vacancies and the doped Co content. Element specific technique, soft X-ray magnetic circular dichroism (XMCD) was used to study the magnetism in Co doped TiO 2 samples. The estimated total magnetic moment by XMCD was in the range of ∼1.3 ± 0.1–2.3 ± 0.2 μ B /Co. This huge magnetization was first time observed by the surface-sensitive Total Electron Yield (TEY) mode. The estimated saturation magnetic moment is in the range of 1.0–1.5 μ B /Co, also consistent with XMCD analysis and cluster model calculation. The results obtained by XMCD recommend an intrinsic behaviour of ferromagnetism. The X-ray absorption spectra (XAS) of Co-doped TiO 2 nanoparticles at Ti L 2,3 and Co L 2,3 -edge in TEY mode concludes that the valence states of Co and Ti ions are in 2 + and 4 + respectively. Cluster model calculation also confirmed that Co ions are in a 2 + valence state with D 2 h high spin crystal-field symmetry at the surface while a random crystal field symmetry in bulk has been observed which is well consistent with experimental data. [Display omitted] • XRD of TCO NPs annealed at 400, 600 and 800°C exhibited the anatase, mix and rutile structures respectively. • The widening and shifting of the E g peak in Raman studies of TCO NPs suggest the formation of oxygen vacancies. • Magnetization of TCO at RT demonstrate FM behaviour, caused by the existence of oxygen vacancies and the doped Co content. • The estimated Ms is in the range of 1.0–1.5 μ B /Co, also consistent with the XMCD and cluster model calculation. • The results obtained by XMCD recommend an intrinsic behaviour of ferromagnetism. • The XAS of TCO NPs at Ti and Co L 2,3 -edge in TEY concludes that Co and Ti ions are in 2 + and 4 + valence states. [ABSTRACT FROM AUTHOR]

• Fe 3 O 4 magnetic nanoparticles with small size (6.5 ± 2 nm) were synthesized by one-step carbothermal synthesis method, and heat generation was spontaneous under alternating magnetic field. • Fe 3 O 4 nanoparticles possess a very strong saturation magnetization of 90.2 emu/g. • The optimum specific absorption rate (SAR) is 43.5 W/g at 15 mT and 245.6 kHz. • The maximum intrinsic loss power (ILP) value is 3.8 nHm2/kg−1. [Display omitted] Induction heating Fe 3 O 4 nanoparticles are commonly used in magnetic hyperthermia. For the best comprehensive efficiency, particles are needed which possess the highest possible heating rates/specific absorption rate when being exposed to a magnetic field. In this paper, a fail one-step carbothermal reduction method for magnetic nanoparticles is optimized towards yielding Fe 3 O 4 nanoparticles with small-size (6.5 ± 2 nm), strong magnetism (90.2 emu·g−1), and high heating rates. The parameters of alternating magnetic field are studied in depth to understand how to produce the best heating rates. Hyperthermia measurements were performed under an alternating magnetic field with a frequency of 165.3 kHz, 245.6 kHz and calculated the specific absorption rate. The optimum specific absorption rate is 43.5 W·g−1 at 15 mT and 245.6 kHz. The maximum intrinsic loss power (ILP) value is 3.8 nHm2·kg−1. [ABSTRACT FROM AUTHOR]

Ferrite magnetic nanoparticles (MNPs) with spinel structure are of great significance in the study of magnetic induction hyperthermia (MIH). The effect of element doping on the magnetic properties of MNPs is crucial. Here, we report the influence of the Mg2+ substitution on Curie temperature (T c), magnetic properties, and heating efficiency of Mg x Zn 0.8- x Co 0.2 Fe 2 O 4 (0.1 ≤ x ≤ 0.5) nanoparticles synthesized by hydrothermal method. With the increase of Mg2+ content, T c increases from 36.7 °C to 242.9 °C due to the enhancement of the A-B super-exchange interaction. The specific saturation magnetization increases from 35.5 emu·g−1 to 53.3 emu·g−1 and then remains constant, which is caused by the effect of Yafet-Kittle angle and magnetic moment. The specific absorption rate (SAR) increases from 3.5 W·g−1to 82.7 W·g−1, which may be ascribed to the effect of size and specific saturation magnetization of the nanoparticles. When x = 0.3, the stable temperature under the alternating magnetic field (32 kA·m−1, 100 kHz) reaches 44.7 °C with the SAR of 49.0 W·g−1. The low toxicity to cells and high heating efficiency endow the MNPs the potential in MIH. [ABSTRACT FROM AUTHOR]

In this paper, temperature-dependent magnetic properties of magnetite nanoparticles (MNPs) synthesized at room temperature via chemical coprecipitation were investigated. Monodispersed MNPs with an average size of 11.22 nm were synthesized at a stirring rate of 200 rpm and a pH value of 10. The phase composition, particle size/morphology, and magnetic properties of the synthesized nanoparticles were characterized by X-ray diffractometer (XRD), scanning transmission electron microscope (STEM) and superconducting quantum interference device (SQUID), respectively. The results show that the synthesized nanoparticles are magnetite with a spinel structure without any impurities. The synthesized MNPs exhibit a nearly spherical morphology with a uniform particle size distribution and an average particle size of 11 nm. Based on the analysis of the temperature-dependent magnetic properties at 5–300 K, the coercivity and remanence in the hysteresis loop for the MNPs decrease with the increase in temperature and disappear at room temperature (i.e., 300 K), thus showing a superparamagnetic behaviour. The superparamagnetic behaviour of the synthesized MNPs was analysed using a developed model based on the core-shell theory. The experimental results of magnetization are in a reasonable agreement with the calculated data by the developed model. The magnetic susceptibility of the synthesized MNPs increases and the coercivity, exchange bias, remanent and saturation magnetizations decrease with the increase of the temperature. It is indicated that the synthesized MNPs could be used as a promising candidate in various applications such as heat transfer, magnetic hyperthermia and magnetic separation. • Synthesis of monodispersed magnetite nanoparticles via coprecipitation method. • Synthesis of highly pure magnetite nanoparticles via coprecipitation method. • Particle size/size distribution control by controlling stirring rate. • Enhanced temperature-dependent magnetic properties of magnetite nanoparticles. [ABSTRACT FROM AUTHOR]