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Recently, metal and metal oxide nanoparticles have garnered significant scientific interest due to their distinctive properties and promising applications across diverse fields. This study details the successful synthesis and characterization of Fe3O4, Ag, and magnetite/silver core-shell (Fe3O4/Ag) nanocomposites, prepared through chemical reduction and co-precipitation methods. The successful incorporation of Ag into Fe3O4 nanoparticles was confirmed through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. Physical characterization revealed that the synthesized nanoparticles were small in size and highly pure. Their optical and electrical properties, including bandgap and electrical conductivity, were also characterized. The antibacterial activity of the synthesized Fe3O4, Ag, and Fe3O4/Ag nanoparticles was evaluated using Minimum Bactericidal Concentration (MBC) against pathogenic bacterial strains: S. typhimurium, P. aeruginosa, and S. aureus. The results demonstrated that Ag, Fe3O4, and Fe3O4/Ag nanoparticles could inhibit high concentrations of bacteria, indicating an excellent antimicrobial effect. Furthermore, the Fe3O4/Ag nanoparticles were found to be more effective than both Fe3O4 and Ag nanoparticles in inhibiting the selected pathogenic bacteria strains: S. typhimurium, P. aeruginosa, and S. aureus. [ABSTRACT FROM AUTHOR]

Industrial wastewater containing heavy metals, toxic compounds, and dyes poses significant environmental concerns. These substances harm aquatic and terrestrial life, making their removal essential for safeguarding biodiversity, ecosystems, and human health. This study focused on synthesizing Fe3O4 nanoparticles (NPs) and their chitosan-coated composite (CS/Fe3O4 NC) for effective wastewater treatment. The NPs were synthesized using the aqueous leaf extract of Laurus nobilis and then coated with chitosan extracted from shrimp. Characterization analysis confirmed the spherical morphology of both Fe3O4 NPs and CS/Fe3O4 NC, with average sizes of 21.3 nm and 28 nm, respectively. The Fe3O4 NPs and CS/Fe3O4 NC exhibited optical bandgap energies of 2.62 eV and 1.81 eV, respectively, indicating their potential as efficient photocatalysts. Photocatalytic efficiency was evaluated using methylene blue (MB) and ortho-toluidine blue (O-TB) dyes. After 75 min, CS/Fe3O4 NC achieved degradation rates of 99% for MB and 98.4% for O-TB, surpassing the rates of 79% and 60.0% achieved by Fe3O4 NPs alone. This highlights the superior performance of CS/Fe3O4 NC in dye degradation. Moreover, Fe3O4 NPs and CS/Fe3O4 NC were effective in removing heavy metals from petroleum water, achieving a remarkable 100% removal efficiency within 30 min. The removal of oil in water was 86% for Fe3O4 NPs and 90% for CS/Fe3O4 NC, while the reduction in total suspended solids was 71% and 78%, respectively. Overall, the synthesized Fe3O4 NPs and CS/Fe3O4 NC demonstrate promising potential for wastewater treatment by efficiently degrading dyes and removing heavy metals, oil, and suspended solids. [ABSTRACT FROM AUTHOR]

We have carried out a systematic investigation on the impact of Fe3O4 nanoparticles (NPs) and Rhizobium inoculation on nodulation and growth of common bean plants (cv. Red Guama, Phaseolus vulgaris). Three distinct treatments were conducted on the common bean plants: (i) exposure to Fe3O4 NPs; (ii) Rhizobium inoculation; and (iii) a combined treatment involving Fe3O4 NPs + Rhizobium inoculation, with non-treated plants as controls. Temperature and magnetic field dependence of magnetization, M(T, H), measurements were performed on both the soil, and dried organs of the plants including roots, nodules, stems, and leaves. M(T, H) analyses indicated a systematic increase in magnetization across organs of plants treated with Fe3O4 NPs and combined Fe3O4 NPs + Rhizobium. We have found the magnetic contribution, generally related to Fe content in the soil and plant organs, significantly increased in plants exposed to Fe3O4 NPs, further indicating absorption, translocation, and accumulation of Fe3O4 NPs in the areal parts of the plants. Plants treated with Fe3O4 NPs and combined Fe3O4 NPs + Rhizobium exhibited Fe3O4 NPs accumulation in all organs with increasing concentrations of 69.7 to 74.1 NNPs/g in roots, 5.6 to 7.7 NNPs/g in stems, and 3.1 to 5.5 NNPs/g in leaves, respectively. The iron concentration in nodules was found to be close to 65 NNPs/g. No appreciable difference in the absorption index AI of roots between plants treated with Fe3O4 NPs (~ 1.73%) and Fe3O4 NPs + Rhizobium (~ 1.79%) has been observed. The translocation index TI increased by ~ 46% in plants treated with Fe3O4 NPs + Rhizobium (6.9%) compared to Fe3O4 NPs (4.3%). Treated plants showed improved symbiotic performance including nodule leghaemoglobin and iron content, number of active nodules per plant, and nodule dry weight. The best result was obtained using the combined treatment of Fe3O4 NPs + Rhizobium. This study provides evidence that M(T,H) measurements constitute a valuable tool in monitoring the uptake, translocation, and accumulation of Fe3O4 NPs in plant organs of common bean plants. [ABSTRACT FROM AUTHOR]

In this investigation, a novel Fe3O4-enhanced biochar derived from winter melon (Fe3O4@WBC) was synthesised by an innovative ethylene glycol reduction and thermal polymerisation approach for efficiently eliminating U(VI) from contaminated environments. The factors influencing uranium(VI) adsorption by Fe3O4@WBC, including pH, adsorbent dosage, time, temperature, and initial U(VI) concentration were explored. The material's performance was characterised, and the underlying mechanism of U(VI) removal was analysed using various techniques. The results demonstrated that Fe3O4@WBC effectively removed U(VI), achieving a maximum adsorption capacity of 199.84 mg g−1 at a pH of 5.0. These findings provided a theoretical basis for the treatment of wastewater contaminated with U(VI). [ABSTRACT FROM AUTHOR]

The experimental study examined the potential impact of biosynthesized triiron tetraoxide nanoparticles (Fe3O4 NPs) on seed germination and germination indices of finger millet (Eleusine coracana) to advance sustainable and biocompatible nano-agriculture. The successful production of Fe3O4 NPs, which was capped with numerous phytochemicals found in the Colocasia esculenta extract, was determined by the results of several characterization processes like FTIR, UV, XRD, and FE-SEM. The presence of the peak in UV with 325 nm with band gap energy 2.60 eV indicates the synthesized NPs. The vibration mode of the Fe–O bond at 530.95 cm−1 and 459.30 cm−1 was analyzed in FTIR. Utilizing XRD, NPs with a mean crystalline size of 3.6 nm were discovered, and crucial EDS examination proved the iron element's presence. The FE-SEM images displayed a nanorod appearance with an average diameter of 43.7 nm whereas DLS shows 739 nm due to the aggregation of nanoparticles. It was observed that the nanoparticle has a significant antioxidant capability which was expressed using several assays. Additionally, this experiment was conducted to examine the impact of biogenic Fe3O4 NPs on the germination of Eleusine coracana seeds as well as to examine other aspects of plant growth, including root and shoot lengths, seed vigor index germination rates, peak value (PV), and mean daily germination. A total of four different Fe3O4 NP concentrations (25, 50, 75, and 100 μg/mL) were investigated. The Eleusine coracana seeds' ability to germinate and thrive is affected by the Fe3O4 NPs' penetration. Efficient treatment with Fe3O4 NPs resulted in a notable improvement in germination index values for Eleusine coracana seeds compared to untreated seeds. In addition to that, the nanoparticles were also treated with Allium cepa and its roots were examined for the mitotic cycle, and lipid peroxidation and Evans blue test were performed. [ABSTRACT FROM AUTHOR]

As the global climate environment continues to change, the frequency of extreme temperature events is expected to increase. The temperature stress environments of low and high temperatures can directly or indirectly affect the growth of rice (Oryza sativa L.), affecting its normal metabolism, which in turn can have an impact on yields and threaten global food security. Agriculture needs new technologies to mitigate temperature stress and improve grain yield and quality. In this study, two iron (Fe)-based nanoparticles (NPs), Fe2O3 NPs and Fe3O4 NPs, as well as groups of Fe ions corresponding to the Fe concentration, were selected for hydroponic experiments on rice under normal (25°C), low (20°C), and high (38°C) temperature conditions, respectively. It was found that low and high temperature stresses reduced stem length (3 and 7.02%), root length (49.53 and 26.01%), and aboveground (52.49 and 26.04%) and belowground biomass (53.94 and 35.22%) in rice. Both Fe2O3 NPs and Fe3O4 NPs could promote root development by nutrient uptake, transferring to the aboveground to enhance photosynthesis, and promoting the activity of antioxidant enzymes to eliminate oxidative stress to alleviate the stress of low and high temperatures. The Fe3O4 NPs were more stable and had obvious effects at both high and low temperatures. [ABSTRACT FROM AUTHOR]

The rampant hepatitis B virus (HBV) seriously endangers human health, and hepatitis B surface antigen (HBsAg) is its early diagnostic marker. Therefore, it is crucial to construct a fast and highly sensitive HBsAg detection method. Based on high-efficiency magnetic separation technology and fluorescent composite material labelling technology, an accurate, fast and sensitive fluorescent immunosensing system for HBsAg detection was developed. Immunomagnetic beads constructed from carboxyl-functionalized Fe3O4 nanoparticles (Fe3O4-COOH) with excellent magnetic response performance were used as efficient capture carriers for HBsAg. Immunofluorescence composite microspheres constructed based on ultra-stable polystyrene-coated CsPbBr3 perovskite nanocrystals (CPB@PSAA) with high hydrophilic properties, were excellent fluorescent markers for HBsAg. Using this sensitive sandwich fluorescence sensing system a good linear relationship within the range of 0.2–15 ng/mL was established between HBsAg concentration and fluorescence intensity with a limit of detection (LOD) of 0.05 ng/mL. The system obtained satisfactory results when tested on real human serum samples. The magnetic-assisted fluorescence immune-sandwich sensor system has broad application prospects in biomedicine such as rapid and early diagnosis and effective prevention of infectious diseases. [ABSTRACT FROM AUTHOR]

In this study, an amperometric dopamine sensor based on carbon nanofibers (CNF), Fe3O4 nanoparticles (Fe3O4NP), and silver nanoparticles (AgNP) modified glassy carbon electrode (GCE) was developed. In order to determine the optimum surface composition, the effects of CNF amount, Fe3O4 amount and the electrodeposition step of AgNP were investigated. Optimum experimental parameters such as working potential and pH of test solution were also explored. The morphological and electrochemical properties of the AgNP/CNF − Fe3O4NP/GCE were studied using scanning electron microscopy, cyclic voltammetry, and chronoamperometry. The AgNP/CNF − Fe3O4NP/GCE showed linear response to dopamine between 2.0 × 10−7 and 5.5 × 10−4 M with a detection limit of 1.8 × 10−7 M and sensitivity of 37.24 μA mM−1. Analytical performance characteristics such as reproducibility, reusability, and selectivity were also investigated for the presented dopamine sensor. The sensor was successfully applied to the detection of dopamine in dopamine hydrochloride injection samples using the standard addition method and good recoveries were obtained. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC), the fifth most prevalent cancer worldwide, is influenced by a myriad of clinic-pathological factors, including viral infections and genetic abnormalities. This study delineates the synthesis, characterization, and the biological efficacy of iron oxide nanoparticles (Fe3O4) and chitosan-coated iron oxide nanoparticles (Fe3O4-CS) against HCC. Analytical methods confirmed the successful synthesis of both nanoparticles, with Fe3O4-CS demonstrating a smaller, uniform spherical morphology and distinct surface and magnetic properties attributable to its chitosan coating. The prepared materials were analyzed using various techniques, and their potential cytotoxic effects on HepG2 cancer cells line for HCC were investigated. In biological evaluations against HepG2 cells, a notable distinction in cytotoxicity was observed. Fe3O4 showed modest anticancer activity with an IC50 of 383.71 ± 23.9 µg/mL, whereas Fe3O4 exhibited a significantly enhanced cytotoxic effect, with a much lower IC50 of 39.15 ± 39.2 µg/mL. The Comet assay further evidenced Fe3O4-CS potent DNA damaging effect, showcasing its superior ability to induce apoptosis through extensive DNA fragmentation. Biochemical analyses integrated into our results reveal that Fe3O4-CS not only induces significant DNA damage but also markedly alters oxidative stress markers. Compared to control and Fe3O4-treated cells, Fe3O4-CS exposure significantly elevated levels of oxidative stress markers: superoxide dismutase (SOD) increased to 192.07 U/ml, catalase (CAT) decreased to 0.03 U/L, glutathione peroxidase (GPx) rose dramatically to 18.76 U/gT, and malondialdehyde (MDA) levels heightened to 30.33 nmol/gT. These results underscore the potential of Fe3O4-CS nanoparticles not only in inducing significant DNA damage conducive to cancer cell apoptosis but also in altering enzymatic activities and oxidative stress markers, suggesting a dual mechanism of action that may underpin their therapeutic advantage in cancer treatment. Our findings advocate for the further exploration of Fe3O4-CS nanoparticles in the development of anticancer drugs, emphasizing their capability to trigger oxidative stress and enhance antioxidant defense mechanisms. [ABSTRACT FROM AUTHOR]

Radiofrequency ablation is a nominally invasive technique to eradicate cancerous or non-cancerous cells by heating. However, it is still hampered to acquire a successful cell destruction process due to inappropriate RF intensities that will not entirely obliterate tumorous tissues, causing in treatment failure. In this study, we are acquainted with a nanoassisted RF ablation procedure of cardiac tumor to provide better outcomes for long-term survival rate without any recurrences. A three-dimensional thermo-electric energy model is employed to investigate nanothermal field and ablation efficiency into the left atrium tumor. The cell death model is adopted to quantify the degree of tissue injury while injecting the Fe3O4 nanoparticles concentrations up to 20% into the target tissue. The results reveal that when nanothermal field extents as a function of tissue depth (10 mm) from the electrode tip, the increasing thermal rates were approximately 0.54362%, 3.17039%, and 7.27397% for the particle concentration levels of 7%, 10%, and 15% compared with no-particle case. In the 7% Fe3O4 nanoparticles, 100% fractional damage index is achieved after ablation time of 18 s whereas tissue annihilation approach proceeds longer to complete for no-particle case. The outcomes indicate that injecting nanoparticles may lessen ablation time in surgeries and prevent damage to adjacent healthy tissue. [ABSTRACT FROM AUTHOR]

Water contamination caused by hexavalent chromium [Cr(VI)] ions has attracted interest since Cr(VI) ions are highly poisonous and carcinogenic, posing major health risks. We report a simple and efficient approach for preparing Fe3O4 nanoparticles and Fe3O4/NiO composite using the chemical co-precipitation method for Cr(VI) removal. The produced magnetic adsorbents could be readily isolated from the solution using an external magnet and were used for Cr(VI) ion adsorption. The adsorbents were characterized by XRD, VSM, FT-IR, FE-SEM, EDX, and BET analyses. The Langmuir type 1 isotherm provided a good representation of the adsorption data when the Langmuir, Freundlich, Temkin, Harkins–Jura, Hasley, and Redlich-Peterson models were utilized to analyze the adsorption isotherm data. The adsorption capacities of Fe3O4 and Fe3O4/NiO composite calculated from the Langmuir type 1 model were 96.15 mg g−1 and 150 mg g−1, respectively. The saturation magnetization of Fe3O4 and Fe3O4/NiO composite was 60.54 emu/g and 11.09 emu/g, respectively. Both adsorbents may be easily and quickly separated from tainted water by an external magnetic field. According to the findings, both adsorbents are possibly reusable adsorbents for Cr(VI) adsorption. The main advantage of the material is that, due to its magnetic nature, it is easily separated from the adsorbate and may thus be used efficiently in sorption studies. As a result, this magnetic adsorbent provides a viable solution for the successful management of chromium-containing wastewater. [ABSTRACT FROM AUTHOR]

This article described a process for the preparation of a Fe3O4 nanocatalyst modified with Mn(II), Cu(II) and Zn(II) ions immobilised with catalase. The effectiveness of the description of the ion sorption process was compared with four equilibrium models: Langmuir, Freundlich, Redlich–Peterson and Sips. The proposed models allow the description of both single- and multi-component sorption. The results were also verified by DFT analysis. The Langmuir model describing single-component sorption and the extended Langmuir model for multi-component systems with the best fit represented the sorption of metal ions on Fe3O4. The maximum sorption capacity values in the pseudo-second-order kinetic model were 10.76, 12.87 and 10.52 mg/g for Cu(II), Zn(II) and Mn(II) in the single-component systems and 11.79, 8.54 and 2.03 mg/g for Cu(II), Zn(II) and Mn(II) in the multi-component system, respectively. The kinetics parameters were described most accurately by a pseudo-second-order model, which suggested, along with the Extended Langmuir model, the chemical nature of the sorption. After preparation of the Fe3O4/Mn–Zn–Cu material, catalase was immobilised on the surface of the material. The final material was able to decompose hydrogen peroxide with an activity of 7130 units/g of material. Modification of the material with Mn(II), Cu(II) and Zn(II) resulted in an increase in H2O2 removal efficiency exceeding 99.9%. [ABSTRACT FROM AUTHOR]

The waste aqueous solutions containing naphthol are treated by physical and chemical methods. However, naphthols are toxic to environment and human health. So it is very important to simultaneously detect them, will make contributions to both the manufacture and the environment management. Herein we developed a simple, cost effective, electrochemical sensor based on magnetite (Fe3O4 nanoparticles) porous reduced graphene oxide/carbon nanotubes (Fe3O4@prGO-CNT) nanocomposite for simultaneous detection of 1-naphthol and 2-naphthol. Voltammetric responses suggest dramatical improvement of electrocatalytic properties of naphthols by incorporating Fe3O4@prGO-CNT on carbon paste electrode (CPE). Differential pulse voltammetric (DPV) measurement depicts large potential separation of about 200 mV between naphthols, allows their simultaneous determination from binary mixture. Under optimized condition, Fe3O4@prGO-CNT/CPE manifested linear relationships of 1-naphthol and 2-naphthol in the range of 0.5–30 and 0.7–40 μM with detection limit (S/N = 3) of 76 and 82 nM respectively. Moreover, Fe3O4@prGO-CNT/CPE showed satisfactory response towards wastewaters and river waters for determining 1-naphthol and 2-naphthol concentrations. [ABSTRACT FROM AUTHOR]

Cholesterol is a lipid molecule in protein and cell membrane and precursor of bile acids, steroids hormones and vitamin D. Higher level of cholesterol, especially low-density lipoprotein (LDL), becomes a cause of cardiovascular disease (CVD). Adsorbent of LDL from human blood plasma plays crucial role for the treatment of hyperlipidemia. Therefore, a suitable adsorbent material for efficient and selective adsorption of low-density lipoprotein is beneficial. In this work, amino acids assisted iron oxide (Fe3O4) was synthesized by hydrothermal method. The morphology, size, crystallinity, and chemical attachment of Fe3O4 nanoparticles are characterized by SEM, FESEM/EDS, HRTEM, XRD, XPS, FTIR, and Raman spectroscopy. The lysine-assisted Fe3O4 (Fe3O4-L) nanoparticles have successfully absorbed LDL in plasma, which shows a higher selectivity, as well as attain outstanding adsorption capacity as high as 30.19% within 1 h. [ABSTRACT FROM AUTHOR]

This work centered on developing an efficient hairy root induction system to achieving a high production capacity of specialized metabolites in Calotropis procera (Aiton) W.T. Aiton. Accordingly, three strain types of Agrobacterium rhizogenes, two different explants (leaf and internodal stem segment), and inoculation suspension containing ½MS medium with 3 and 6% sucrose were studied. Besides, inoculation methods including injection and immersion with or without wounding as well as two inoculation times (5 and 30 min) were examined. Afterwards, the hairy roots were treated with different concentrations of synthesized Fe3O4 nanoparticles (Fe3O4 NPs) and salicylic acid (SA) to improve growth and productivity. The high frequency of transformation was observed in pre-pricked leaf explants immersed in the suspension consisting A4 strain and half-strength MS with 6% sucrose. Also, the result illustrated that the application of NPs had a positive effect on increasing growth, soluble sugars, total proteins and antioxidant enzymes and reduction H2O2 and MDA levels. This effect was significantly greater in the hairy roots treated with both Fe3O4 NPs and SA compared to those exposed to these elicitors individually. In addition, the comparison between the essential oil components of intact plant and the transformed hairy root of C. procera confirmed that hairy root culture, especially supplemented with Fe3O4 NPs and SA, has potential ability to greater production of essential oil. This study suggests that Fe3O4 NPs and SA together can be used as powerful elicitors to improve growth and yield in hairy roots. Key message: This study demonstrates a valuable method in hairy root induction system for Calotropis procera and improvement of their growth and physiological characteristics by Fe3O4 nanoparticles and salicylic acid. [ABSTRACT FROM AUTHOR]

In the present work, carbon paste electrode was modified by reduced graphene oxide–graphene quantum dots–Fe3O4 (RGO/GQDs/Fe3O4) nanocomposite and employed for dopamine detection. The characterization of the RGO nano-sheets, RGO/GQDs and RGO/GQDs/Fe3O4 nanocomposites was performed by field emission scanning electron microscopy–energy dispersive spectroscopy (FESEM/EDX) and transmission electron microscopy (TEM). The electrochemical behavior of the electrodes was investigated by cyclic voltammetry that the results showed a significant increase in peak current for RGO/GQDs/Fe3O4/CPE. Under the optimized empirical conditions, efficiency of the RGO/GQDs/Fe3O4/CPE sensor for dopamine determination was examined using cyclic voltammetry and differential pulse voltammetry methods. A linear relationship between dopamine concentration and the peak current was discovered for modified electrode over a wide range from 5 to 150 μM with the limit of detection of 3.43 μM and 5–160 μM with the limit of detection of 1.43 μM in CV and DPV methods, respectively. Based on chronoamperometry studies, it was determined that the oxidation process of dopamine on the surface of the modified electrode is controlled by its diffusion from inside the solution to the surface of the electrode. The obtained values of diffusion coefficient and rate constant for dopamine using the chronoamperometry method were 1.3 × 10–8 cm2 s−1 and 22.9 × 108 cm3 mol−1 s−1, respectively. The good applicability of the proposed sensor for dopamine analysis in real samples was reported by obtaining suitable recovery values in the range of 96.5–103%. [ABSTRACT FROM AUTHOR]

In this research, a type of magnetic ionic liquid-based nanoparticles (MNPs@PIL) was designed and prepared via free radical polymerization. The structure of MNPs@PIL was characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, and Fourier-transform infrared spectroscopy. MNPs@PIL were successfully applied as a selective adsorbent for the extraction of ciprofloxacin and levofloxacin in water and human urine samples by using the magnetic solid-phase extraction method. The effects of different factors such as pH of sample solution, adsorbent amount, sample volumes, adsorption and desorption time, temperature, and ion strength were studied. Under the optimum experimental conditions, the limits of detection of the proposed method for ciprofloxacin and levofloxacin were obtained as 0.05 and 0.03 ppm, respectively. The reusability experiments showed that about 95% of the initial adsorption was obtained after ten cycles. [ABSTRACT FROM AUTHOR]

Fe3O4@L-Arginine and Fe3O4@L-Histidine nanoparticles (NPs) are synthesized and explored as catalysts for the sequential Knoevenagel condensation and Michael addition reactions (KMS). The reaction parameters like the amount of catalyst, temperature, and solvent systems are optimized for both of the catalysts for the Knoevenagel condensation reaction. It was observed that the developed catalyst systems work well under solvent-free conditions at 80 °C. Excellent to high yield was achieved in the corresponding Knoevenagel adducts (up to 97%), in turn, delivered good yield in Michael products (up to 70%). Surprisingly, Fe3O4@L-Hist NPs did not show any catalytic activity for the sequential Michael addition. The probable reasons for the high activities of Fe3O4@L-Arg NPs for KMS have been discussed. The catalyst was also recovered and reused for 5 cycles with equal performance in terms of activity and selectivity. The optimized protocol for sequential Knoevenagel condensation and Michael addition reaction can result in high isolated yields with saving in the cost of solvent and falls under the domain of green chemistry. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles are prominently used in wastewater treatment for the removal of a range of contaminants. However, the usage of toxic and costly chemicals for their synthesis greatly limits their applications. Herein, we developed a cheap and sustainable process to synthesize magnetite nanoparticles (SS–Fe3O4NPs) by employing the extract of Sargassum spp.—an abundantly available marine macroalgae along the Western coastal region of India. The morphological and structural features of SS–Fe3O4NPs were analyzed using various methods. Agglomerated spherical particles were witnessed in FESEM and TEM images and the elemental Fe and O were noticed in the EDS analysis. The crystalline nature was confirmed from SAED and XRD analyses. The lattice parameter value of 8.3545 Å obtained using XRD data confirmed the standard crystal structure of magnetite. XPS study corroborated the oxidation states of Fe and O, which are specific for magnetite. The presence and the role of the biomolecules in the synthesis of SS–Fe3O4NPs was ascertained from FTIR and XPS studies. In addition, the EDS, XRD, and XPS analyses revealed the purity of the SS–Fe3O4NPs. The high magnetic saturation value of 65.85 emu/g portrayed the magnetic nature of the synthesized SS–Fe3O4NPs. The magnetite nanoparticles were thermally stable until 800 °C with an overall weight loss of 6.21%. Raman spectrum showed the signature peak of magnetite at 668 cm−1. The BET specific surface area was 45.11 m2/g, marginally higher than the commercial counterpart. The synthesized magnetite nanoparticles exhibited remarkable catalytic efficiency to degrade methylene blue dye, showing 98% degradation in 25 min, establishing the rapidness of the process. Therefore, the SS–Fe3O4NPs synthesized herein, could play a significant part in the management of dye-laden industrial wastewater effectively. [ABSTRACT FROM AUTHOR]

This work aims to control the random laser performance using magnetic-plasmonic nanoparticles including Fe3O4 and Au nanoparticles mixed with the active laser media R6G dye. For this purpose, Au nanoparticles were produced via the electrical exploding wire method and mixed with the Fe3O4 nanoparticles in the dye medium. After characterizing the samples through the transmission electron microscopy and the florescence spectra in the visible region, they were pumped by the second harmonic generation of the Nd: YAG laser where the random lasing action was detected by a spectrometer. These measurements were performed with and without external magnetic field at 35 mT. The results revealed a nice full width at half maximum of random laser efficiency in the samples exposed to the external magnetic field. In addition, using the external magnetic field, the coherency percentage of the random lasing action diminished because of the fixed direction of the magnetic field which was collinear to the cell direction that can affect the coherency loop due to nanoparticles' arrangement direction in the dye medium. [ABSTRACT FROM AUTHOR]

A novel, simplistic approach for the synthesis of bio-mediated magnetite nanoparticles has been reported by employing an aqueous leaf extract of Elaeocarpus Sylvestris plant as a green source. The synthesized Elaeocarpus Sylvestris capped MNPs (ESMNPs) were investigated by different spectroscopic, electronic microscopic and thermal analysis techniques. The ESMNPs exhibited a strong absorption peak at 352 nm, FTIR studies confirmed the Fe–O bond, XRD patterns ascertained the crystalline nature & average crystallite size of 8.3 nm, EDAX studies evaluated 69.52% of iron and 30.48% of oxygen. ESMNPs were spherical in morphology, polydisperse in nature, with a size range of 6–80 nm and agglomeration of some particles, as determined by SEM and TEM techniques. The superparamagnetic nature was proved by the VSM technique, and it was brought to good attention in the isolation of ESMNPs. The thermal stability was revealed by TGA analysis. The results of all characterizations agreed that the synthesised particles were ESMNPs. The ESMNPs were tested for their antimicrobial and antioxidant activity. It is proved that ESMNPs showed antibacterial activity against gram-negative E. coli & gram-positive Staphylococcus aureus and antifungal activity against Aspergillus niger. Further, antioxidant efficiency with ascorbic acid against the DPPH assay method was performed. The current study shows a path for a futuristic wave for synthesizing MNPs with a wide range of applications. [ABSTRACT FROM AUTHOR]

The effect of polydopamine (PDA) modification on aminated Fe3O4 nanoparticles (Fe3O4-NH2)/graphite oxide (GO)/β-cyclodextrin polymer cross-linked by citric acid (CDP-CA) composites were studied for the removal of a cationic dye (methylene blue, MB) and an anionic dye (Congo red, CR) from waters. The micro-structural and magnetic characterizations confirmed the successful preparation of Fe3O4-NH2/GO/CDP-CA and PDA/Fe3O4-NH2/GO/CDP-CA composites. The maximum MB and CR adsorption capacities of Fe3O4-NH2/GO/CDP-CA were 75 mg/g and 104 mg/g, respectively, while the corresponding amounts for PDA/Fe3O4-NH2/GO/CDP-CA composite were 195 mg/g and 64 mg/g, respectively. The dye sorption behaviors of these two composites were explained by their corresponding surface-charged properties according to the measured zeta potential results. Moreover, the high saturation magnetizations and the stable dye removal rate in the adsorption–desorption cycles indicated the good recyclability and reusability of the fabricated composites. [ABSTRACT FROM AUTHOR]

The preparation and characterization of ultrafine superparamagnetic Fe3O4 (magnetite) nanoparticles and their composites with the PMMA polymer matrix are described. The cubic structure with space group (Fd 3 ¯ m) of the nanofiller particle Fe3O4 is revealed by x-ray diffraction (XRD) studies. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to examine the microstructure and elemental compositions of PMMA-Fe3O4 polymer composites. The interaction of the filler particles with the characteristic functional group of the polymer PMMA was detected using Fourier-transform infrared spectroscopy (FTIR). UV-spectroscopy studies revealed that PMMA-Fe3O4 nanocomposite films have tunable energy band gap properties, with the band gap decreasing as the magnetite filler particles (Fe3O4) in the polymer matrix increased. Magnetic measurements revealed the superparamagnetic nature of the Fe3O4 nanoparticles at room temperature, which was also found to be present in the nanocomposites. These nanocomposites were found to be ferrimagnetic at low temperatures (5 K) similar to that of the nanoparticles (Fe3O4). The blocking temperature (TB) of the nanocomposites was found to increase with the superparamagnetic Fe3O4 nanoparticle content, while the saturation magnetization (Ms) of the polymer nanocomposites decreased consistently. The Ms value was also estimated using TGA data, and the Ms values of different nanoparticles and nanocomposites calculated via TGA correlates with those determined from VSM analysis. [ABSTRACT FROM AUTHOR]

A magnetic graphite-epoxy composite (m-GEC) electrochemical sensor is presented based on magnetic imprinted polymer (mag-MIP) to determine homocysteine (Hcy). Mag-MIP was synthesized via precipitation polymerization, using functionalized magnetic nanoparticles (Fe3O4) together with the template molecule (Hcy), the functional monomer 2-hydroxyethyl methacrylate (HEMA), and the structural monomer trimethylolpropane trimethacrylate (TRIM). For mag-NIP (magnetic non-imprinted polymer), the procedure was the same in the absence of Hcy. Morphological and structural properties of the resultant mag-MIP and mag-NIP were examined using TEM, FT-IR, and Vibrating Sample Magnetometer. Under optimized conditions, the m-GEC/mag-MIP sensor showed a linear range of 0.1–2 µmol L−1, with a limit of detection (LOD) of 0.030 µmol L−1. In addition, the proposed sensor responded selectively to Hcy compared to several interferents present in biological samples. The recovery values determined by differential pulse voltammetry (DPV) were close to 100% for natural and synthetic samples, indicating good method accuracy. The developed electrochemical sensor proves to be a suitable device for determining Hcy, with advantages related to magnetic separation and electrochemical analysis. Highlights: • A novel mag-MIP with specific recognition sites for selective detection of homocysteine (Hcy) was prepared • The prepared platform allowed successful recovery percentages of Hcy in different matrices • Differential pulse voltammetry (DPV) was applied in urine and synthetic plasma • Selectivity was obtained in the presence of other biothiols • This platform showed advantages related to a combined magnetic separation and an electrochemical analysis • The sustainability of the procedure concerns easier and cheaper pre-treatment and a biomimetic replacement of unstable biomolecules [ABSTRACT FROM AUTHOR]

In the current article, to decline the temperature of heat element, enclosure with the wavy wall has been utilized with incorporating magnetic source. The wire near the inner surface generates the space-dependent Kelvin force. Adding nano-sized powder into H2O creates a new fluid which has a higher capability to absorb heat. Defining vorticity term creates the simpler format of equations and CVFEM was utilized for simulation. To test the correctness of code, the previous published article was considered and a low amount of error percentages illustrates the nice accuracy. The space-dependent Kelvin force affects the nanomaterial and increase the convective flow and strength of eddy increase. As nano-sized material added, Nu enhances around 12.79% owing to augmentation of conductivity. When MnF = 2000 and zero, augment of Ra makes the Nu to augment around 1.04% and 47.94%. When Ra = 1e4, augment of Kelvin force causes Nu to grow around 35. 36%. [ABSTRACT FROM AUTHOR]

Metal oxides, due to their low cost, environmental friendliness and wide sources, have attracted great attention. We chose iron oxide/graphene oxide (Fe3O4/GO) nanohybrids to modify a PU sponge to increase the surface roughness of the sponge without damaging its inherent structural properties. The composite was then treated with octadecane thiol to reduce the surface energy and produce a superhydrophobic and oleophilic absorption material with a water contact angle of 157°. From the absorption experiment with simulated oily water (including diesel oil, lubricating oil, rapeseed oil, chloroform, N,N-dimethyl formamide, tetrahydrofuran, ethanol and acetone), it was found that the Fe3O4/GO-modified PU sponge could absorb up to 80–170 times its own weight while showing outstanding recyclability achieved by squeeze/absorption cycles. Moreover, the composite absorption material exhibited weak magnetic properties, suggesting its recycling practicability. These results provide a quick and simple strategy to deal with oil spills and chemical leakage. [ABSTRACT FROM AUTHOR]

Micromagnetic simulations are applied in order to investigate the effect of shape on the magnetic permeability and loss tangent for Fe3O4 nanoparticles in the frequency range of 0.5 to 20 GHz. Fe3O4 nanoparticles with 6 different shapes and equal volumes are studied in two groups: spherical particles, and prismatic particles with a hexagonal base. Our results show that, generally, elongated particles demonstrate higher microwave magnetic permeability. Moreover, we find that elongation reduces the resonance frequency in prismatic particles, while increases it in spherical ones. These results are important in designing advanced microwave absorbers, as they can be used to predict the effective permeability of a composite medium containing a certain percentage of magnetic nanoparticles. [ABSTRACT FROM AUTHOR]

Magnetic cellulose (MC) is prepared by hydrolysis of iron precursors in an aqueous dispersion of cellulose nanofibers. A thin, flexible film was then prepared by removing the water and drying the sample in a hot press at 110 °C followed by the removal of the water. Structural analysis of MC was performed and correlated with the measurement of electromagnetic properties. The magnetic cellulose showed high magnetic saturation of 68 emu/g with characteristic superparamagnetic behaviour, and conductivity in a range of semiconductors, with an increase of direct current (DC) conductivity with increasing temperature. Modification of cellulose with Fe3O4 has a positive effect on the DC conductivity and lower limit that needs to be exceeded to achieve a stable and sustainable conductivity in the range of ~ 5–20 × 10–9 (Ω cm)−1 @30 °C is 65 wt% of the Fe3O4 for studied MC composites. The surface roughness of the magnetic cellulose shows a dynamic change with increasing temperature, which is closely related to the enhancement of MC conductivity. A theoretical model of the conductivity is calculated based on continuous 2D percolation and shows an interesting agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (Ag NPs) were reduced on the surface of magnetic sporopollenin (Fe3O4@SP) modified with poly-dopamine to enhance the degradation capability for Rhodamine B (RhB). The polydopamine-coated Fe3O4@SP (PDA@ Fe3O4@SP) acts as a self-reducing agent for Ag+ ions to Ag0. The structural properties of the synthesized nanocomposite were determined using Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), and vibrating sample magnetometer (VSM). The systematic study of the degradation process was performed using Response Surface Methodology (RSM) to determine the relationship between the four process variables, namely, initial RhB concentration, NaBH4 amount, catalyst amount, and time. Optimum points were determined for these four parameters using both matrix and numerical optimization methods. Under optimum conditions, RhB was decolorized with a yield of 98.11%. The apparent activation energy (Ea) and rate constant (k) for the degradation were 24.13 kJ/mol and 0.77 min−1, respectively. The reusability studies of the Ag@PDA@Fe3O4@SP exhibited more than 85% degradation ability of the dye even after five cycles. As a result, Ag@PDA@Fe3O4@SP possessed high catalytic activity, fast reduction rate, good reusability, easy separation, and simple preparation, endowing this catalyst to be used as a promising catalyst for the decolorization of dyes in aqueous solutions. [ABSTRACT FROM AUTHOR]

Calotropis procera (Aiton) W.T.Aiton presents high levels of medicinally important terpenes and phenolics with antiinflammatory, antimicrobial, and antioxidant properties. The present study aimed to develop a suitable platform for mass production of pharmacological metabolites and improvement of antioxidant activity of C. procera. Motivated by such aim, potential effects of Fe3O4 nanoparticles (Fe3O4 NPs) and salicylic acid (SA) on antioxidant defense response and essential oils in seedlings and hairy roots were investigated. 21-day-old seedlings were treated by five levels of Fe3O4 NPs (0, 50, 100, 150, and 200 mg L−1) and three SA concentrations (0.0, 0.05, 0.1 mM). Moreover, the hairy roots about 2 cm were transferred into MS liquid medium supplemented with the above-mentioned concentrations of Fe3O4 NPs and 0 and 0.01 mM SA. After treatment, total phenolics, flavonoids, flavonol, anthocyanin, activity of polyphenol oxidase and l-phenylalanine ammonia-lyase, ferric-reducing antioxidant power, 2, 2‑diphenyl‑1‑picrylhydrazyl and production of essential oils were analyzed. Results demonstrated that hairy root culture is a powerful alternative for improving and inducing secondary metabolites of C. procera as compared to seedlings. Moreover, it was found that Fe3O4 NPs combined with SA have the more ability than all other treatments to improve antioxidant activity and essential oil in both seedlings and hairy roots. Here, 100 and 200 mg L−1 Fe3O4 NPs combined with 0.01 mM SA had more pronounced impact on induction of pharmacological constituents and antioxidant activity. Results suggest that Fe3O4 NPs and SA in hairy root culture can bring great insights into development in vitro biosynthesis of valuable secondary metabolites. Key message: Synthesized magnetic Fe3O4 nanoparticle combined with the salicylic acid in hairy root culture may be considered as a good alternative approach for the mass production of antioxidant and novel pharmacological metabolites of Calotropis procera. [ABSTRACT FROM AUTHOR]

To control Fe3O4 nanoparticles (Fe3O4 NPs) size, different molar ratio of Fe2+ and Fe3+ as well as ammonium hydroxide (pH) was used to synthesize Fe3O4 NPs through co-precipitation method. The Box–Behnken design was selected to explore the interaction between process parameters (factors) such as Fe2+ molar ion, Fe3+ molar ion and pH on the final size. The interactive effect between the process variables was evaluated by analysis of variance (ANOVA). The quadratic model predicted by the Box–Behnken design was significant with a P value of < 0.0001. The optimum synthesis conditions were predicted by the model indicating optimum size obtained using 1.00 mol Fe2+ ion with 3.00 mol Fe3+ ion with pH at 12.00. From the experiment, the particle size was 10 ± 2 nm at optimum conditions, while the model predicted a particle size of 6.80 nm. The magnetic properties of Fe3O4 NPs were displayed typical ferromagnetic behavior with saturation magnetization value to be 49.729 emu/g. Finally, the optimized Fe3O4 NPs showed about 80% removal of Congo red (CR) dye, which confirms their applicability in adsorption process for future applications. [ABSTRACT FROM AUTHOR]

Raw canola stalk (RCS) and water vapor–activated biochar (B35, B36, B37, ..., B57) adsorbents were utilized to remove lead (Pb) from polluted solutions. The water vapor–activated biochar adsorbents were prepared in three carbonization temperature levels and three activation temperatures. The best water vapor–activated biochar adsorbent (B57) was selected for carrying out adsorption isotherm experiments on the lead at 25 °C. Experiments were then conducted to determine the best pH level and the best adsorbent dosage, which were found equal to 6 (pH), and 0.3 g sorbent per 30 mL of pollutant, respectively. Next, both RCS and B57 were modified to obtain 5%, 10%, and 15% sorbents using magnetic iron oxide nanoparticles (Fe3O4). The lead adsorption isotherm experiments were carried out using the new modified adsorbents. The results indicated that the water vapor–activated biochar adsorbent modified with Fe3O4 (B57 5%) are the best adsorbents for the lead pollutants' removal. The results were compared within a 5% significance level. TEM, BET, VSM, FT-IR, and XRD analyses were undertaken for sample specification. The analyses showed that the Fe3O4 nanoparticles are modified on the adsorbents. [ABSTRACT FROM AUTHOR]

Development of electric branches caused by partial discharge leads to degradation in the performance of epoxy resin insulation materials, which seriously threatens the safe and stable operation of power equipment. In this study, n-tetradecanol (MA)@polystyrene microsphere (PS)@Fe3O4 core–shell phase change microcapsules were designed and prepared. Doping 0.1 wt% phase change microcapsular material into the epoxy resin cured compound inhibited the development of electric branches. SEM and EDS tests showed that the phase-change microcapsules had monodisperse spherical core–shell structures with an MA encapsulation rate of 24.73% and excellent phase-change thermal storage capacity. Electric field simulations revealed that Fe3O4 nanoparticles in the microcapsule shell enhanced the local field strength of the cured epoxy resin and induced the development of electric branches toward the interior of the microcapsule. Moreover, doping of microcapsules into the epoxy resin significantly slowed the rate of temperature rise and thus inhibited further development of electric branches in epoxy resin cured products. In comparison with the epoxy resin cured without microcapsules, it was found that the longitudinal and transverse lengths of electric branches were reduced by 56.6% and 69.1%, respectively, in the epoxy resin cured with 0.1 wt% MA@PS@Fe3O4 microcapsules, and the electric branch initiation field strength was increased from 0.57 to 0.68 kV/mm. This indicated that MA@PS@Fe3O4 microcapsules significantly improved the electrical branch resistance of epoxy resin cured products, and this provides a new approach for extensive applications of epoxy resin insulation materials and safe and stable operation of power equipment. [ABSTRACT FROM AUTHOR]

In this work, a novel water-soluble Salen type Cu(II) Schiff base complex functionalized silica-coated magnetite nanoparticles [Fe3O4@SiO2/Schiff base of Cu(II)] was synthesized and characterized. First, an immobilized water-soluble Schiff base was synthesized from the condensation reaction between 3-amino propyl triethoxy silane (APTES) functionalized silica-coated magnetite nanoparticles and a water-soluble aldehyde (sodium salicylaldehyde-5-sulfonate monohydrate). After that, functionalized Schiff base was converted to functionalized Cu(II) Schiff base complex as the result of reaction with Cu(II) acetate tetrahydrate. The structural and magnetic properties of the prepared compounds were identified by FT-IR, XRD, SEM, EDX, TEM, VSM, and TGA. The catalytic activity of the novel nanocatalyst was investigated for the preparation of 2-amino-4H-chromene derivatives through an one-pot, three-component reaction of dimedone, aromatic aldehydes, and malononitrile, in the presence of catalytic amounts of the Fe3O4@SiO2/Schiff base of Cu(II) nanocatalyst in water and at room temperature. The 2-amino-4H-chromene derivatives were obtained in good to excellent yields. Furthermore, because of the solubility of metal Schiff base complexes in water, the nanocatalyst dispersed in water easily without using ultrasonic or shaker. [ABSTRACT FROM AUTHOR]

In this study, nanocomposite hydrogels based on chitosan/magnetic nanoparticles (Fe3O4 NPs) and Mg–Al double-layered hydroxides (LDH) were prepared as pH-sensitive drug delivery systems for loading and controlled release of diclofenac. The effect of using Fe3O4 NPs in nanocomposites was compared with chitosan and chitosan/LDH hydrogel beads. Sodium tripolyphosphate was used as physical crosslinker agent. The prepared nanocomposites were characterized by Fourier transform infrared spectroscopy, vibrating sample magnetometry (VSM), X-ray diffraction patterns, and scanning electron microscope analyses. The drug release and swelling behavior of these hydrogels have been investigated in aqueous solutions at different pH and under applying the external magnetic field (EMF). The results indicate that swelling and drug release of chit/LDH/Fe3O4 nanocomposites were affected by pH and EMF. The maximum equilibrium swelling of the nanocomposites contains 0.05, 0.10, and 0.15 wt% of Fe3O4 NPs at pH value of 1.2 are 634, 594, and 578% and at pH value of 7.4 are 99, 95, and 90% and at pH value of 9.3 are 57, 53, and 51%, respectively. By increasing of the Fe3O4 NPs content in nanocomposites, the rate of diclofenac release was slower than to control samples and so can concluded that drug release has become more targeted. The percent of drug release for chit/LDH/Fe3O4 nanocomposites under EMF value 0.5 T at pH = 1.2 and 7.4 and 9.3 was at the range of 58.3–76.4% and 20.0–25.1 and 18.3–16.2%, respectively. [ABSTRACT FROM AUTHOR]

In this study, Fe3O4 nanoparticles and chitosan along with silver nanoparticles was synthesized to apply for the rapid and simple removal of amoxicillin (AMX) from aqueous environment. The characterization of fabricated adsorbent was carried out using scanning electron microscope, Energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction analysis. Four experimental variables, including pH, contact time, adsorbent dosage, and initial AMX concentration were optimized using response surface methodology based on the central composite design. The maximum removal efficiency was obtained 89.17% with pH of 4, contact time of 40 min, adsorbent dosage of 0.4 g L−1, and initial concentration of 20 mg L−1. The effect of parameters on the removal performance was assessed using analysis of variance via the second-order polynomial model. The adsorption of AMX onto the synthesized adsorbent was more consistent with the Langmuir model with a coefficient of determination (R2) equal to 0.9991 than with the Freundlich model (R2 = 0.9165). The maximum adsorption capacity of the adsorbent was obtained 43.10 mg g−1. The pseudo-second-order kinetic model represents the most adequate correlation of empirical data compared to the pseudo-first-order (R2 = 1). The proposed adsorbent could be considered as an effective and low-cost adsorbent for the AMX removal from aqueous media. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles (MNPs) and nanocomposites can be used in different applications including catalysis reactions and applications. Magnetic nanocomposites can be reused and magnetically filtrated after catalysis reaction. For this purpose, Fe3O4 MNPs were produced using the co-precipitation technique. Fe3O4 MNPs were coated with SiO2 shell, APTES and G2 PAMAM dendrimers and lastly doped with Au and Ag nanoparticles (Fe3O4@G2/Au/Ag) which has been examined for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 as a model reaction. Physical structures of the nanocomposites were characterized using SEM and TEM which illustrate that nanoparticles were in composite form. Chemical composition of nanostructures was confirmed using EDX and FTIR. Magnetic characteristics were checked using VSM. Dendrimerization and Au and Ag nanoparticle doping on catalytic and magnetic properties were deeply assessed. PAMAM dendrimer coating on Fe3O4 nanoparticles results in a slightly decreased magnetic saturation value and in the reaction rate of 4-NP reduction. Au and Ag embedding in PAMAM dendrimers slightly increases the reaction rate while reducing the overall magnetic saturation values of nanocomposites. [ABSTRACT FROM AUTHOR]

A one-pot synthesis method of polymer–metal–carbon nanomaterials in the interfacial process was developed. Ternary nanocomposites are single-walled carbon nanotubes (SWCNT) with immobilized magnetite nanoparticles, coated with polydiphenylamine-2-carboxylic acid (PDPAC). The chemical structure and morphology of the obtained hybrid Fe3O4/SWCNT/PDPAC nanocomposites were investigated by FTIR spectroscopy, X-ray diffraction, transmission electron microscopy and field emission (FE-SEM) scanning electron microscopy. The size of Fe3O4 nanoparticles is within the range of 2 < d < 14 nm. Multifunctional nanocomposite materials exhibit thermal, electrical and magnetic properties. Fe3O4/SWCNT/PDPAC nanocomposites were used for preparation of stable magnetic fluids in water and ethyl alcohol. [ABSTRACT FROM AUTHOR]

In the present study, an adsorbent with a synergistic effect was developed from chitosan (CS) and Fe3O4 nanoparticles (Fe3O4 Nps) to remove Cr(VI) from aqueous solutions. The Fe3O4 Nps were synthesized by co-precipitation and were characterized by TEM. The CS/NPs composites were prepared by electrospinning technique and analyzed by SEM, FT-IR, DSC, and TGA. In the batch system, the influence of Fe3O4 Nps content, pH, contact time, Cr(VI) initial concentration, adsorbent dosage, and the temperature was investigated; the Cr(VI) concentration was determined using a colorimetric method by UV–Vis spectroscopy. The Fe3O4 Nps presented a quasi-spherical shape and an average size of 18 nm, with a low particle distribution. The SEM analysis reveals the presence of highly porous, interconnected micrometric structures. The optimal adsorption conditions were 1% load of Fe3O4 Nps by weight of CS, pH 3, 25 °C, and equilibrium was reached at just 9 min. Besides, the adsorption is favored by increasing Cr(VI) initial concentration and adsorbent dosage. The studies of reaction kinetics and adsorption equilibrium showed that the experimental data were better fitted to the Pseudo-second-order and Langmuir isotherm models, establishing monolayer formation and chemisorption. The maximum adsorption capacity of CS/Fe3O4 Nps was 440.75 mg/g, which indicates a high affinity of the adsorbent for Cr(VI). Finally, a kinetic diffusion study established that intraparticle diffusion, and in particular surface diffusion, are important resistances in the transport of Cr(VI) from the liquid phase to the active site. [ABSTRACT FROM AUTHOR]

Herein, we report a simple, efficient, and cost-effective solid-phase extraction method using magnetic coffee residue as adsorbent for extraction and determination of titanium dioxide nanoparticles (TiO2 NPs) from environmental water samples. The adsorbent was prepared by modifying spent coffee residue using magnetite nanoparticles as magnetic medium through modified chemical precipitation technique, and the TiO2 NPs were synthesized by a sol–gel method. The prepared materials were characterized by X-ray diffractometry, scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. Factors affecting the extraction conditions were optimized, including effect of pH (4), sample volume (25 mL), amount of adsorbent (0.075 g), vortexing time (3 min), initial concentration (70 mg L–1) and the desorption conditions. Under optimum conditions, the developed method exhibited high extraction efficiency (94%), a wide linear range (100–500 μg L–1) and a limit of detection (LOD) of 12 µg L–1. Moreover, the method showed excellent intra- and inter-day precision, with relative standard deviations (% RSD) of 3.47% and 4.58%, respectively. More importantly, the current method demonstrated great potential for the extraction and quantification of TiO2 NPs in river, lake and effluent water samples and exhibited good percentage recovery. Therefore, the developed method can be used for monitoring level of TiO2 NPs in different sample matrices. [ABSTRACT FROM AUTHOR]

Cost-effective simultaneous determination of mercury, copper and cadmium ions was performed by differential pulse anodic stripping voltammetry (DPASV) using a pencil graphite electrode (PGE) modified with poly-L-cysteine (P-L-Cys) and Fe3O4 nanoparticles. Electropolymerization of L-cysteine was performed by cyclic voltammetry (CV) through applying different cycles. Also, Fe3O4 was deposited in a single step by applying a constant potential on the electrode surface in the presence of ferric nitrate. To enhance the sensitivity of measurement, several parameters such as monomer concentration, scan rate, number of cycles in electropolymerization, ferric nitrate concentration, Fe3O4 electrodeposition potential and time, and pH of the sample solution were optimized. The surface morphology of the modified electrode was examined by SEM and FTIR. Electrochemical impedance spectroscopy was conducted to investigate the impedance of the electrode surface. The linear ranges for cadmium, copper and mercury were 0.001‒2500, 0.0002‒3600 and 0.0001‒2500 nM with detection limits of 6.4 × 10–13, 1.0 × 10–13 and 9.0 × 10–14 M, respectively. The stability and reproducibility of the electrode were investigated. Finally, the modified electrode was applied to determine mercury, copper and cadmium in real samples such as the groundwater, Caspian Sea and Tajan River water. [ABSTRACT FROM AUTHOR]

A novel molecularly imprinted electrochemical sensor based on ferric oxide nanoparticles modified glassy carbon electrode (GCE) was fabricated for detection of human growth hormone (HGH). The stable proteins molecularly imprinted polymer (MIP) films were made by electro-polymerization using aniline as functional monomer and HGH as the template. Electropolymerization was done in a range of − 0.3 to + 0.9 V at a scan rate of 0.1 V s−1 for 15 cycles. The accuracy of MIP/Fe3O4/GCE formation was confirmed using the square wave voltammetry technique from − 0.2 to + 0.6 V, in 5 mM solution of [Fe(CN)6]3−/4− with 0.1 M KCl. According to the results, the sensor showed a linear range from 1.0 × 10−10 to 1.0 × 10−7 g/cm3 of HGH (R2 = 0.9588) under optimal conditions with a detection limit of 0.6 × 10−10 g/cm3. The calibration curve showed a 95.8% correlation of the data. The human plasma sample analysis confirmed the applicability of the MIP/Fe3O4/GCE sensor to the assay of the HGH molecules. In conclusion, the sensor has sensitivity, high stability, and good repeatability. [ABSTRACT FROM AUTHOR]

Carbohydrate polymers were widely used in pharmaceuticals and drug delivery systems due to their biodegradability and biocompatibility. Among them, chitosan (Cs) has been considered in many new drug delivery systems. Poly(ethylene glycol) as a hydrophilic polymer can increase the solubility and stealth functions of nanocarriers. The Fe3O4 nanoparticles functionalized with polymers act as non-toxic drug vehicles for tumor targeting under external magnetic fields. In present study, the Fe3O4/SiO2-NH2 nanoparticles were prepared and then functionalized with methoxy-PEGylated chitosan (Cs-g-mPEG2000) and the hydroxyurea (HU) was loaded on this nanoparticles. The structure, crystallinity, and morphology of HU/Fe3O4/SiO2/Cs-g-mPEG2000 were determined using spectroscopic and electron microscopy analysis. Encapsulation efficiency of HU and the percentage of loading and release rate at different pH values at 37 °C were examined. Maximum drug release was observed at pH = 7.4. According to TEM results, the nanoparticle sizes were between 18 and 157 nm. The cytotoxicity effect of HU-loaded nanoparticles against MCF-7 human breast cancer cell was evaluated using MTT assay and cell cycle arrest analysis. The inhibitory concentration (IC50) values were 249 and 85 μg/mL on the MCF-7 cell line compared to the control group in 24 h and 96 h, respectively. In addition, the expression of p53 and lincRNA-P21 genes in treated cells and control group was assessed using real-time PCR, and the results showed that the ratio of p53 expression to lincRNA-P21 in MCF-7 cells was significantly increased (P < 0.05). The cell cycle arrested in the S-phase and the population of cells increased 1.3-fold compared to the control group. [ABSTRACT FROM AUTHOR]

In this report, portable, quantitative, and sequential monitoring of copper ions and pyrophosphate (PPi) with a single sensor based on a DNAzyme-Fe3O4 system and glucometer readout was performed. Initially, streptavidin was functionalized on the surface of magnetic Fe3O4 spheres through glutaraldehyde. Then, an invertase-modified DNA Cu substrate was connected to the magnetic Fe3O4 spheres by a specific reaction between streptavidin and biotin. The sensing system was formed by a hybridization reaction between the Cu substrate and Cu enzyme. In the presence of Cu2+, Cu2+ will recognize the Cu DNA substrate and form an "off-on" signal switch, thereby resulting in the separation of invertase from the Fe3O4 nanospheres. PPi recognizes Cu2+ to form a Cu2+-PPi complex, resulting in an "on-off" signal switch. Under optimized conditions, linear detection ranges for Cu2+ and PPi of 0.01–5 and 0.5–10 μM, and detection limits for Cu2+ and PPi of 10 nM and 500 nM, respectively, were obtained. Good selectivity was achieved for the analysis of Cu2+ and PPi. Satisfactory results were achieved for this biosensor during the determination of Cu2+ in real tap samples and PPi in human urine samples. This verified that the sensor is portable and low cost, and can be applied to the sequential monitoring of multiple analytes with a single point-of-care biosensor. [ABSTRACT FROM AUTHOR]

Small glucose-modified liposomes (GMLs) were loaded with magnetic Fe3O4 nanoparticles (MNPs) and fluorescein using a standard thin layer preparation procedure and a varying lipid/MNPs ratio. The liposomes were characterized with TEM and DLS measurements, and MNPs encapsulation rate was determined using ICP-OES. Prepared liposomes were stored at 5 °C for 30 days and subsequently exposed to an external magnetic field (20 mT) with varying exposure times (2‒20 min), at room temperature. The release of fluorescein from GMLs induced by the magnetic field exposures was quantified, showing a high release rate (25‒85%) depending on the concentration of MNPs in GMLs. EPR measurements were conducted during the liposomes storage period in order to provide semi-quantitative information of possible MNPs oxidation from Fe3O4 to Fe2O3 inside the liposomes, impacting MNPs magnetic properties. In contrast to the MNPs water dispersion, no significant change in the EPR signal of MNPs encapsulated inside GMLs was detected over the course of 30 days. The data presented in this study indicate that GMLs loaded with MNPs maintain a high stability for prolonged periods of time and that this delivery system may be used for magnetically assisted controlled drug release. [ABSTRACT FROM AUTHOR]

liquid marbles are liquid droplets that encapsulated with hydrophobic micro-nano sized particles. These liquid soft solids, as a promising digital microfluidic systems, offer a simple alternative to conventional discrete microfluidic systems and may have wide applications in biomedical, biochemistry and nanotechnology. In this experimental and numerical study, first, for production of magnetic liquid marbles, Fe3O4 magnetic nanoparticles were synthesized and hydrophobized with paraffin wax. Second, by slight rolling of water droplet on Fe3O4@Isoleucine-P wax nanoparticles, the formation of our magnetic liquid marble is achieved. Third by modeling our liquid marble by a droplet with an elastic shell, the effect of gravity on marble shape simulated and verified with experimental results. The results obtained from the simulation analysis fit well to the experimental data describing the shape of liquid marble under the force of gravity. [ABSTRACT FROM AUTHOR]

In the present work, the adsorption performance of powdered activated carbon magnetized by iron(III) oxide magnetic nanoparticles (PAC@Fe3O4-MN) for the removal of ciprofloxacin (CIP) was extensively studied using batch experiments. First, PAC@Fe3O4-MN was synthesized and prepared by co-precipitation method, then it was subjected to characterization study using advanced techniques. Then, the adsorption ability of PAC@Fe3O4-MN for CIP was determined at different initial CIP concentration (10–100 mg/L), pH (3–11), PAC@Fe3O4-MN dose (0.1–0.6 g/L), shaking speed (50–300 rpm), contact time (0–120 min) and temperature (283–328 K). Results showed that PAC@Fe3O4-MN possessed excellent adsorptive properties and had a high practical utility. It was found that PAC particles were partially covered during the magnetization by Fe3O4-MN whereas the surface and morphological properties of both were detected in the characterization analysis of PAC@Fe3O4-MN. Values of the thermodynamic and isotherm parameters (negative Δ G o ; positive Δ H o , and values of KF and B) indicated that CIP adsorption process onto PAC@Fe3O4-MN was favorable, spontaneous and endothermic. Kinetic and isotherm studies manifested that the interaction of CIP with PAC@Fe3O4-MN occurs via both chemical and physical reactions onto a single and homogeneous layer of active sites of PAC@Fe3O4-MN. Furthermore, the rate-controlling step of the kinetic reaction is dominated and controlled by film diffusion for all CIP concentrations that studied. PAC@Fe3O4-MN possessed an excellent adsorption capacity for CIP (109.833 mg/g at pH 7, PAC@Fe3O4-MN dose = 1 g/L, shaking speed = 200 rpm, initial CIP concentration = 100 mg/L, contact time = 60 min, and temperature = 298 K). Finally, the used adsorbent appeared to be sustainable and cost-effective for treatment of CIP laden wastewater, as it can be successfully recycled up to eight consecutive adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

In this study, a colloidal gel of magnetic Fe3O4 nanoparticles was used in the development of a simple and accurate dispersive solid phase extraction method for the extraction/preconcentration of trace levels of cobalt ions in urine samples. The eluted cobalt ions were determined by slotted quartz tube-flame atomic absorption spectrophotometry (SQT-FAAS). The effects of the type and volume of buffer solution, volume of magnetic colloidal gel, type and period of mixing, concentration and volume of the eluent were investigated and optimized to obtain the best experimental outputs. Under the optimum conditions, the limits of detection and quantification were found as 4.6 and 15 ng mL−1, respectively. The developed method provided a 61.5 folds enhancement in the detection power of the flame atomic absorption spectrophotometry. Method validation was performed by spiking experiments using matrix matching method. The percent recoveries were found to be close to 100% for the spiked samples, which validate the accuracy and the applicability of the developed method to the urine samples. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles (Fe3O4 NPs) have received considerable attention in various biomedical applications due to their fascinating properties and multiple functionalities. In this multidisciplinary study, Fe3O4 NPs were produced by an inexpensive co-precipitation technique and using four different weight percentages of Punica granatum fruit peel extract as a green stabilizer. From the image of transmission electron microscopy, the NPs showed spherical shapes with an average size of 14.38 nm. Results of UV–VIS spectroscopy and bandgap indicated successful preparation of the Fe3O4 NPs stabilized with the extract. Adding the stabilizer concentration improved the particle zeta potential from −29.24 to −35.62 mV. Thermoresponsive performance of the Fe3O4 nanofluids with the green extract could render a remarkable heating capability under the hyperthermia condition. Magnetic resonance imaging (MRI) analysis presented that the samples possessed acceptable MRI signals. An anticancer drug 5-fluorouracil was successfully loaded onto the Fe3O4 NPs containing 2 weight percentage of the extract, which indicated a maximum release of 79% in a media with pH 7.4. In cytotoxicity assays, the drug-loaded Fe3O4 NPs at 15.62 and 31.25 µg.ml−1 concentration eliminated 29% and 35% of HCT116 colorectal cancer cells, respectively. This study, therefore, introduced that the green-synthesized Fe3O4 NPs can be a promising candidate for magnetic hyperthermia therapy, MRI nanoagents and drug delivery in colorectal cancer. [ABSTRACT FROM AUTHOR]