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A series of CuO/NiO nanoparticles with different Cu and Ni precursor concentrations represented as N12 (1:2), N22 (1:1) and N21 (2:1) (Cu2+:Ni2+) were produced by modified green solution combustion route using Moringa oleifera leaves extract as an organic fuel. The prepared CuO/NiO nanoparticles were analytically characterized using UV-Vis diffuse reflectance spectroscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and vibrating sample magnetometry. Morphological studies showed uniform and nearly monodisperse nanoparticles having average grain size of 34 nm for N22 nanoparticles while the N12 and N21 compositions showed uniform nanoparticles with the grain size of 12 nm and 22 nm respectively. The existence of CuO and NiO phases in nanoparticles was verified by XPS analysis. N12, N22 and N21 had band gaps in the range of 2.19–2.49 eV and specific surface area in the range of 4.92–11.2 m2/g. The susceptibility vs. temperature plots for mixed oxides nanoparticles showed distinct magnetic behaviour for different ratio. The coercivity and saturation magnetization reached a maximum value for N22 (130 Oe and 0.133 emu/g). These biogenic nanoparticles could be a strong choice for biological applications due to their soft magnetic behaviour and biocompatibility. [Display omitted] • CuO/NiO nanoparticles with varying ratio (1:2; 1:1 and 2:1) were prepared. • Green solution combustion (using Moringa extract) was adopted for the synthesis. • Optical, structural and magnetic properties were investigated. • VSM measurements exhibited a distinct magnetic character for each ratio. [ABSTRACT FROM AUTHOR]

The present study reports the synthesis and physico-chemical characterization of Mn 1−x Zn x Fe 2 O 4 (x = 0.5, 0.4, 0.3, 0.2, 0.1) nanoparticles-based magnetic fluids with reference to magnetic fluid hyperthermia. The properties of these fluids are studied using XRD, FTIR, TGA, VSM and the induction heating equipment operated at 330 kHz. The heating response of the fluids is investigated within the safety limit of H·f (4.8 *108 A/m-s). The study is also extended to simulate it for the agarose gel phantom system. The power absorption by these samples in distilled water and in agarose gel is calculated to compare with the experimentally observed value. To the best of the author's knowledge, no study of temperature sensitive magnetic fluid is reported on agarose gel, which simulates or phantom an in vivo condition. Results analysis show that the control of hyperthermia temperature is possible at lower fields and frequencies for the A91 sample with the smallest possible concentration, which can be acceptable for in vitro study. • The synthesis and physico-chemical characterization of Mn 1−x Zn x Fe 2 O 4 nanoparticles (x = 0.5, to 0.1) based magnetic fluids is reported. • The heating response of the fluids is investigated within the safety limit of H·f (4.8 *108 A/m-s). • The power absorption by these samples are calculated to compare with the experimentally observed value. • To the best of author's knowledge, study of temperature sensitive magnetic fluid in agarose gel is not reported yet. • Results show that the A91 sample controls hyperthermia temperature at lower field, frequency and lowest concentration. [ABSTRACT FROM AUTHOR]

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]

This work is an attempt to obtain gadolinium-doped hematite Gd x Fe 2−x O 3 (x = 0, 0.05, and 0.1) using the hydrothermal method followed by heat treatment. The work also studies the impact of gadolinium doping on the magnetic, electrical, and optical properties of hematite. X-ray diffraction (XRD) analysis, energy-dispersive X-ray spectroscopy (EDAX) and photoelectron spectroscopy (XPS) showed that the obtained phase for all samples was pure hematite with no evidence of secondary phases, indicating a high solubility limit of gadolinium ions in hematite lattice. The morphology and size distribution of the particles were investigated using high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). It was found that the lattice parameters increased with increasing gadolinium concentration. Magnetization was not enhanced whereas, the coercivity decreased considerably. From UV–Vis diffuse reflection spectroscopy (DRS) measurements, the band gap energies of pure and doped α-Fe 2 O 3 decreased from 2.01 to 1.94 eV respectively. Moreover, measurements of electrical properties showed that the dielectric permittivity decreased while the resistivity increased with increasing the gadolinium content. In addition, sulforhodamine B (SRB) test against oral epithelial cell lines showed low cytotoxicity of the particles. Finally, gadolinium doped hematite is introduced as a novel, environmentally benign material for potential applications in various fields including photocatalysis for water treatment, biosensor and as an antibacterial agent. [Display omitted] • The obtained samples exhibit a corundum structure with no impurities. • The coercivity of hematite decreased whereas saturation magnetization was not enhanced. • The dielectric loss decreased, and the resistivity increased, rendering Gd-doped hematite for microwave applications. • The band gap decrease makes the material useful for photocatalysis, and light energy conversion as a biosensor. • The biocompatibility of the particles makes it a potential material for industrial and medicinal applications. [ABSTRACT FROM AUTHOR]

Superparamagnetic magnetite (Fe 3 O 4) has potential biomedical applications, but its synthesis can be challenging and costly. We present a simple and facile method for synthesizing superparamagnetic magnetite via the co-precipitation method. The pH and stabilizer concentration were optimized to obtain high purity Fe 3 O 4 nanoparticles with superparamagnetic characteristics, despite having an aggregated morphology. The results showed that the synthesized particles were micrometer-sized, and exhibited superparamagnetic behavior with a value of 40 emu/g. The conventional wisdom on superparamagnetic behavior is to attribute the phenomenon to the presence of nanosized crystallites and nanoparticles in the aggregated structure, however, our computational analysis through density functional theory shows that strain-related effects are an underlying cause for the paramagnetism of magnetite as well, which explains our experimental observations. Overall, the co-precipitation method presented in this study offers an easy, non-toxic, and fast method for synthesizing Fe 3 O 4 nanoparticles, which is suitable for industrial-scale production. [Display omitted] • Fe 3 O 4 particles were micron-sized, exhibiting superparamagnetic behavior of 40 emu/g. • Strain-related effects are an underlying cause for the paramagnetism of Fe 3 O 4 powders. • Tetrahedral Fe vacancy formation is favored in nanosize range. • The spin channels are fully symmetric on DOS patterns of strained Fe 3 O 4. [ABSTRACT FROM AUTHOR]

Cobalt-zinc ferrite nanoparticles having composition Co 1-x Zn x Fe 2 O 4 were processed by sol-gel method with particle sizes ranging from 10.8 nm to 3.6 nm. The crystal structure, particle size, and magnetic properties were investigated by XRD, FTIR, TEM, and VSM techniques. Single domain nature was established from the coercivity versus particle size curve. The dependence of specific saturation magnetization with zinc concentration was discussed in terms of site occupancy of cations and supported by FTIR measurements. A few single domain nanoparticle compositions exhibiting low Curie temperatures and reasonably good magnetization were subjected to induction heating measurement to explore the possibility of using the materials for magnetic hyperthermia. The material, having the composition, Co 0.37 Zn 0.63 Fe 2 O 4 was shown to be an excellent candidate for conducting hyperthermia study with self-regulated temperature at 46 °C. • Nanoparticles of size from 3.6 nm to 10.8 nm were synthesized by sol-gel method. • The chelating agent, polyvinyl alcohol was found to be powerful in controlling the particle size. • The transition from multi-domain to single domain nanoparticle was established with zinc concentration. • The composition Co 0.37 Zn 0.63 Fe 2 O 4 was developed with Curie temperature, 46 °C. • Self regulated magnetic hyperthermia in the composition, Co 0.37 Zn 0.63 Fe 2 O 4 was achieved. [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]

Magnetic nanoparticles of high saturation magnetization with least particle size are essential candidates for certain biomedical applications like hyperthermia. The development of such nanoparticles requires stringent processing conditions in arriving at desired characteristics. Magnesium substituted cobalt ferrite nanoparticles of size around 4 nm were processed by sol-gel method with high saturation magnetization and characterized by techniques XRD, TEM, FESEM and FTIR in elucidating the structural parameters. Magnetic properties were discussed in terms of a proposed cation distribution and occupancy of magnesium was established from electrical resistivity measurements. [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]

Although, the ideal hard ferromagnetic particles are much better energy absorbers as against the ideal superparamagnetic particles, the use of hard ferromagnetic materials in hyperthermia applications has always been a major challenge for researchers due to their high anisotropy. This work introduces a route to use a hard magnetic material (SrFe 12 O 19 ) in the form of nanoparticle and scaffold in hyperthermia application. Single domain SrFe 12 O 19 nanoparticles, with a hard magnetic behavior, when composited with hydroxyapatite (HA), allowed the use of the minimum frequency and amplitude of the alternative magnetic (AC) field to have high amount of specific absorption rate. This was the outstanding advantages of this work, especially when a monodispersed HA-SrFe 12 O 19 nanocomposite was used. HA-10 wt%SrFe 12 O 19 scaffolds, after gelatin coting, showed a high stable compressive strength with a high uniform interconnected porosities. Besides, HA-10 wt%SrFe 12 O 19 composite nanoparticles showed a high specific absorption rate in both mono and multi dispersed states. [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]

Magnetic nanoparticles (MNPs) functionalized with biocompatible surface find numerous applications in health care sectors including hyperthermia treatment. In the present study, we report the synthesis of nickel ferrite nanoparticles in calcium phosphate nanostructure via hydrothermal assisted wet precipitation method using sucrose as an organic modifier followed by rapid thermal processing. The phase composition, morphology and magnetic properties were further investigated through various characterization techniques. The obtained product exhibits ferromagnetic behaviour with coercivity of 0.045 T at 5 K and the superparamagnetic behaviour with zero coercivity at 300 K which suggests that it may be a potential material for hyperthermia treatment. [ABSTRACT FROM AUTHOR]

Ni 1- x Zn x Fe 2 O 4 (0 ≤ x ≤ 1) nanoparticles were synthesized via co-precipitation method in order to study their structural and magnetic properties as well as their heating efficiency. Structural results show that the annealed samples at 1000 °C exhibit a single cubic spinel structure while the mean crystallites size is ranging from 70 to 130 nm, as x increases. Rietveld refinement was also performed to deduce both cation distribution and lattice parameter. Mössbauer spectroscopy at room temperature shows the decrease of the average hyperfine field with the increase of the zinc content. Magnetic curves indicate that saturation magnetization was increased with the increase of zinc concentration, up to x = 0.5, then decreased. These results have been explored to explain the magnetic heating characteristics of the samples under an AC magnetic field at a fixed frequency. The intrinsic loss power (ILP) of sample with x = 0.5 is found about 0.42 nH m2kg-1, this value allows the use of x = 0.5 for the in-situ hyperthermia treatment of cancer cells as application. • Ni 1-x Zn x Fe 2 O 4 nanoparticles were successfully synthesized by co-precipitation method. • Average crystallite size is in the range of 70 and 130 nm. • Magnetic properties were studied through Mössbauer and SQUID measurements. • Law approach to saturation is used to study the dependency of magnetization on the applied field. • Highest ILP value was 0.42 nH m2 kg-1, obtained for the sample with x = 0.5. [ABSTRACT FROM AUTHOR]

Ferromagnetic nanoparticles (NPs), with high heating efficiency, have great potential as heating elements for use in magnetic hyperthermia and thermoablation therapies. In this work, core@shell structured Fe@Fe 2 O 3 nanochains were prepared by facile chemical reduction of Fe 2+ ions in aqueous solution. The resulting nanochains were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), elemental mapping, Raman analysis, and magnetization measurements. It was found that Fe nanochains form through connection of Fe nanospheres one by one and are coated by amorphous Fe 2 O 3 layer. The chains are about 50–100 nm in diameter and several micrometers in length. Magnetic measurements revealed that as-prepared nanoconstructs possess typical ferromagnetism with a characteristic blocking temperature above 400 K. The saturation magnetization of the samples prepared at 25 °C, 40 °C and 80 °C are 118.6, 81.9, 22.8 emu/g and the coercivity are 136, 259 and 411Oe, respectively. It was interesting to find that these nanochains, dispersed in water at physiological pH, present higher heating efficiency than that of superparamagnetic ferrite NPs. The enhanced heating performance of Fe@Fe 2 O 3 nanochains may be attributed to the activation of a magnetic hysteresis loss mechanism. This study indicates that the resulting Fe@Fe 2 O 3 nanochains are promising materials in magnetic hyperthermia and thermoablation therapies. [ABSTRACT FROM AUTHOR]

• The solvo-thermal synthesis method was used to obtain flower-like morphology of MnFe 2 O 4. • Intrinsic loss power of ~ 5.31 nH m2 kg−1 was observed during magnetic hyperthermia due to modified magnetic behaviour. • Even 100 µg/mL could produce temperature (~ 42 °C) during PTT with a photo-thermal conversion efficiency of ~ 63%. • Photo-luminescence spectroscopy showed intense peak in NIR region, corroborates well to the impressive heating behaviour. [Display omitted] Magnetic nanoparticles (MNPs) have emerged as efficient materials for thermo-therapeutic modalities viz. magnetic fluid hyperthermia (MFH) and photo-thermal therapy (PTT). Nevertheless, the quest to further enhance the effectiveness of such materials is a major challenge to their successful endeavour. In the present work, we have synthesised MnFe 2 O 4 nano-flowers utilising solvo-thermal method to be employed as nano-heat generators during MFH and PTT. The material, in addition to effective heating under an alternating magnetic field (AMF), demonstrated impressive heating ability under near infra-red (NIR) irradiation. Various techniques, such as, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photo-electron spectroscopy (XPS) and Mössbauer spectroscopy were used to study the structural features and chemical composition of the sample. The photoluminescence spectroscopy (PLS) has further corroborated the efficient heating behaviour of the sample under NIR irradiation. The observed intrinsic loss power value of 5.31 ± 0.079 nH m2 kg−1 is significantly higher than the commercially available ferro-fluids and comparable to previously reported values for iron oxide nano-flowers. A substantial SiHa cells death during photo-thermal treatment was noticed at a concentration of 500 μg/mL of MnFe 2 O 4 nano-flowers after exposure to 808 nm laser of 0.66 W cm-2 power density for only 10 min. However, at the same concentration of nanoflowers (i.e. 500 μg/mL) and exposure time (i.e. 10 min) during MHT with SiHa cells, a significant decrease in cell viability was not observed. [ABSTRACT FROM AUTHOR]

• Hybrids show high ability of AMF, 808 and 1122 nm conversion into heat energy. • Synergic action of external stimuli allows for maximizing temperature effect on hybrids. • Effective conversion of AMF on composites can be used in modern EMI materials. • High hybrid responsiveness for AMF and laser light can be used in biomedical field [Display omitted] Hybrid materials composed of inorganic magnetic cobalt-manganese mixed nanoferrites and PMMA polymeric shell have been fabricated by applying an in-situ polymerization process using pre-prepared inorganic core particles (8–9 nm). The ability of the hybrid heating under action of alternating magnetic field and laser radiation (in a separate and synergy mode) was evaluated and compared with stock nanoparticles. It was found that hybrid materials show a high response to both stimulants and the highest temperature was achieved by using both AMF and laser exposure under synergic mode (twice the value for the AMF alone). The specific absorption rate of composite material was around 30 W/g for the optimized field parameters and both laser wavelengths (808 and 1122 nm). The great response of the hybrid material for contactless action of AMF and NIR radiation makes the proposed material very interesting for future biomedical and EMI shielding applications. [ABSTRACT FROM AUTHOR]

• Synthesis of Fe 3 O 4 nanoparticles and surface modification with CA, DEX and APTES. • The correlation of the SAR with the magnetite surface-modifier intrinsic properties. • Biosensors construction by modification of SPC electrodes with coated magnetite. • The relationship of biosensor efficiency with surface-modifier of SPC electrodes. • Development of the electroanalytical procedure for the determination of dopamine. [Display omitted] The citric acid (CA), dextran (DEX) and (3-aminopropyl)triethoxysilane (APTES) are frequently used ligands for surface modification of magnetite nanoparticles to improve their colloidal stability and biocompatibility for use in biomedicine. Here we report the synthesis, surface modification of magnetite (Fe 3 O 4) nanoparticles and analysis of the influence of coating materials on heating efficiency in magnetic hyperthermia, as well as on electrochemical sensing toward the detection of neurotransmitter dopamine (DOP). Spherical magnetite nanoparticles (~13 nm) were prepared by co-precipitation and surface-modified with CA, APTES and DEX. The hyperthermia tests revealed that Fe 3 O 4 @APTES resulted in the highest specific absorption rate (SAR) of 67.2 W/g. The engineered sensor, by surface modification of screen-printed carbon (SPC) electrodes with Fe 3 O 4 @APTES, showed linear response with DOP in the concentration range of 1−200 μM and a low detection limit of 34.3 nM. Besides, the sensor offered remarkable selectivity, repeatability and reproducibility. Application of SPC-, Fe 3 O 4 -, Fe 3 O 4 @CA- and Fe 3 O 4 @DEX-modified SPC electrode resulted in lower electrocatalytic activity compared with Fe 3 O 4 @APTES/SPC. The obtained results indicate the effects of a surface modifier especially that Fe 3 O 4 @APTES, alone and combining with SPC electrodes, can serve as an agent in various types of biomedical applications, like hyperthermia and electrochemical sensing of biologically active compounds such as DOP. [ABSTRACT FROM AUTHOR]

An attempt has been made to bridge between the influence of surface modification at nanoscale and the biomedical applicability of multifunctional nanocomposite. Fe 3 O 4 synthesized via solvothermal route has been made nanocomposite with Polyethylene glycol (PEG) and Amine functionalized Multiwall Carbon nanotube (MWCNT). Formation of Fe 3 O 4 phase has been confirmed by X-ray diffraction (XRD). Functionalization of MWCNT with PEG and Amine has been recognized by Fourier transform infrared (FTIR) Spectra. Thermogravimetric analysis (TGA) discerned the adhesion of functional groups onto MWCNT and also the loading of functionalized MWCNT in the nanocomposite. Besides the visible evidence of interaction of spherical Fe 3 O 4 onto walls of MWCNT provided by High-resolution transmission electron microscopy (HRTEM), there are other inferences led by the influence of this functionalized group. Crystallographic information from Rietveld analysis of the XRD pattern infers the impact of functionalized MWCNT on cation distribution in the Fe 3 O 4 spinel structure. Vibrating sample magnetometer (VSM) studies revealed near superparamagnetic nature of as-synthesized samples, with 17% rise and 19% fall in the Coercivity of PEG-o-MWCNT/Fe 3 O 4 and Amine-o-MWCNT/Fe 3 O 4 than bare Fe 3 O 4 respectively. A comparison of the Specific absorption rate suggested that under an oscillating magnetic field, nanocomposites are capable as an agent of heat generation as bare Fe 3 O 4 , even better at the higher field amplitude for tuning with magnetic anisotropy. • Oxygen in PEG-o-MWCNT, reduces discrepancy in surface oxygen coordination of Fe 3 O 4 yielding almost ideal inverse structure. • σ-donor in Amine-o-MWCNT leads to high spin state of d5-orbitals of Fe3+ ion, so that octahedral site preference energy becomes higher. • In PEG-o-MWCNT/Fe 3 O 4 HC increases, since π-donation contracts the CFSE. • In Amine-o-MWCNT/Fe 3 O 4 HC decreases, since σ-donation expands the CFSE. • With increase in HA, heating efficiency (SAR) of nanocomposite increases at faster rate than bare Fe 3 O 4. [ABSTRACT FROM AUTHOR]

• MNP-CC@SiO 2 multicore@shell NPs loaded with curcuminoids preparation is showed. • The nanoplatform showed good colloidal stability, dispersibility and magnetic properties. • A good theranostic system for biomedical applications such as fluorescent biomarker and magnetohyperthermia agent. [Display omitted] Theranostic systems have gained much attention due to their widespread biological and technological applications. In this work, we report the synthesis and characterization of a theranostic nanoplatform based on multicore magnetic iron oxide functionalized with curcuminoids (CC) and coated with silica (MNP-CC@SiO 2). The physicochemical and colloidal properties of the unloaded-curcuminoids nanoplatform (MNP@SiO 2) were evaluated by several techniques, including X-ray diffraction, magnetometry measurements, transmission electron microscopy, and zeta potential and dynamic light scattering. The time and maximum loading of curcuminoids onto multicore MNP (MNP-CC) were investigated by adsorption kinetic and isotherm. After the curcuminoids loading, MNP-CC was coated with amorphous silica to prevent pervasion, degradation of the curcuminoids, and providing colloidal stabilization to the system. The resulting MNP-CC@SiO 2 exhibits expressive fluorescence, in addition to interesting magnetic and thermal properties. On the other hand, this device shows a negligible release of curcuminoids in sink conditions. The potential theranostic features of MNP-CC@SiO 2 nanoplatform are attributed to the combination of a multicore magnetic structure with a silica coating. We argue that this should provide a versatile and multifunctional nanoplatform. It is expected to present potential biomedical applications, such as image contrast, magnetic hyperthermia treatment, cell separation, and drug delivery. [ABSTRACT FROM AUTHOR]

• Iron carbide (Fe 5 C 2) nanoparticles show ferromagnetic properties with high saturation magnetization. • Fe 5 C 2 nanoparticles reveal an extended optical absorption property. • We have demonstrated Fe 5 C 2 nanoparticles as a hyperthermia heat probe with dual magneto-photo-thermal therapeutic features. • Fe 5 C 2 nanoparticles suspension displays enhanced SAR values relative to that of Fe 3 O 4 nanoparticles. Localized heat generation using nanoparticles is a promising supplementary technique to the well-established cancer treatments, such as chemotherapy and radiotherapy. Here, we demonstrate that iron carbide (Fe 5 C 2) nanoparticles with a thin carbon shell have the collective magnetothermal and photothermal effects based on the ferromagnetic and photonic properties. When the Fe 5 C 2 nanoparticle suspension is irradiated with a NIR laser (808 nm), it yields unprecedented heating effects. Further, owing to the observed high magnetization and coercivity, the Fe 5 C 2 nanoparticle suspension on exposure to an alternating magnetic field (ACMF) exhibits an enhanced specific absorption rate (SAR) as compared to Fe 3 O 4 nanoparticles of the same size. This significant improvement in the SAR arises from the cooperative contribution from the hysteresis and susceptibility losses. This work also gives quantitative information about the ACMF effects on heating ability as well as provides some guidelines for obtaining enhanced heating activity in nanoparticle suspensions of a given magnetic material. [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]

Ultrasmall magnetic particles are notorious for exhibiting a magnetization increase even at quite intense applied fields, behavior which can be interpreted as a non-saturation of the magnetic disordered shell even if the nanoparticle magnetization is reversible. In this work we study two kinds of ultrasmall core@shell nanoparticles (3 nm) with contrasting core anisotropy, composed of MnFe 2 O 4 and CoFe 2 O 4 cores covered by a thin maghemite layer. In order to investigate the saturation criterion associated to the closure of major loops (in contrast to minor loops), we use several procedures to determine, at moderate fields, if the effective anisotropy energy barrier is overcome or not. Firstly, we carefully evaluate the closure field of the hysteresis loop, interpreted as the effective anisotropy field, correspondent to two different contributions. One, arising from the nanoparticle core, is related to the coercivity and the other one is associated to pinned spins of the nanoparticle shell. Secondly, the ZFC-FC magnetization measurements taken at different fields give us information about both the anisotropy energy barrier distribution and the thermal dependence of effective anisotropy field. Thirdly, forced minor loops are performed, measured after either ZFC or FC processes, to counter-check the effective magnetic anisotropy at low temperature of both samples. Finally, we perform major hysteresis loop calculations in order to better understand the magnetization processes involved. To go further, we propose in this study a procedure to extract information about the two contributions which composes the effective magnetic anisotropy field. • Two kinds of ultrasmall core@shell nanoparticles are synthesized by coprecipitation. • The magnetic saturation criteria are analyzed due the magnetic effects on nanoscale. • The exchange bias effect is also analyzed in terms of saturation magnetization. • By closure field analysis we propose a method to extract the anisotropy constants. • We perform calculations of hysteresis loops based on Stoner & Wohlfarth theory. [ABSTRACT FROM AUTHOR]