Vibrating Sample Magnetometry Research Articles

Degradation of malachite green by g-C3N4-modified magnetic attapulgite composites under visible-light conditions.

Water resources are seriously threatened by dye wastewater, and the removal of the dye molecules from the wastewater has garnered considerable interest. People have favored photocatalytic technology in recent years for the treatment of dye wastewater. In this work, attapulgite (ATP) was used as a carrier, Fe3O4 and g-C3N4 were grafted onto ATP, and the surface was then modified with polyethyleneimine (PEI) to produce photocatalyst ATP-Fe3O4-g-C3N4-PEI, which was used in Malachite green (MG) dye wastewater. The structure and surface properties of the composites were analyzed and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray spectrum (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Uv-vis spectrum analysis, zeta potential measurement, and vibrating-sample magnetometry (VSM) analysis. The removal performance of ATP-Fe3O4-gC3N4-PEI for MG was studied, and the removal mechanism was explored and revealed. It has been shown that the heterojunction formed by Fe3O4 and g-C3N4 can inhibit the compounding of photogenerated electrons and holes, effectively improving the performance of the ATP-Fe3O4-g-C3N4-PEI. Electron paramagnetic resonance (EPR) analysis confirmed that ATP-Fe3O4-g-C3N4-PEI could generate hydroxyl radicals (·OH) and superoxide radicals (·O2-) to degrade the MG. It was believed that ATP-Fe3O4-g-C3N4-PEI could generate hydroxyl radicals (·OH) through the photocatalysis and the Fenton reaction of the composite materials. Under the action of H+, ·O2-, and ·OH, the removal rate of MG by ATP-Fe3O4-g-C3N4-PEI exceeded 98 % at an optimal condition. The intermediate products and degradation pathways of MG degradation were also inferred by LC-MS analysis. These results showed that the prepared photocatalyst has excellent degradation performance for MG and could be used in dye wastewater treatment.

Copper ferrite immobilized on chitosan: A suitable photocatalyst for the removal of ciprofloxacin, ampicillin and erythromycin in aqueous solution

Copper ferrite (CuFe2O4) was immobilized on chitosan to produce CuFe2O4@Chitosan for the removal of ciprofloxacin (CIP), ampicillin (AMP), and erythromycin (ERY) in water. Characterization of CuFe2O4@Chitosan by X-ray diffraction revealed the crystallite size of 18.12 nm. The Brunauer-Emmett-Teller surface area is 9.95 m2 g−1. The vibrating sample magnetometry revealed a saturation magnetization of 37.69 emu g−1. The degradation efficiency by CuFe2O4@Chitosan towards CIP (94.6 ± 0.50%), AMP (92 ± 1.00%) and ERY (90.30 ± 0.50) presents it as a promising photocatalyst for the removal of antibiotics in aqueous solutions. Regeneration capacity showed CuFe2O4@Chitosan to be a promising photocatalyst for removal of antibiotics in water.

Magnetic properties of layered Ni/Cu nanowires

In this paper, the structural and magnetic properties of layered nanowires (NWs) made of alternating layers of nickel and copper were investigated. NW arrays were obtained by matrix synthesis. The nickel layers had a fixed thickness of 400 nm, and the thickness of the copper layers varied from 25 to 300 nm. The magnetic characteristics of such NWs were studied in two states: in a matrix (integral magnetic characteristics determined using vibrating sample magnetometry) and for individual NW (local magnetization visualized using MFM). For NWs in the matrix, the hysteresis loops measured for the two directions of the magnetic field become identical when the thickness of the Cu layer increases to 300 nm, which is due to the weakening of the dipole interaction between the Ni layers. The coercive force (190 Oe) and the residual magnetization (0.32 Ms) in the parallel direction of the field are maximal for the thickness of the Cu layer equal to 100 nm, which corresponds to the diameter of NWs and the distance between them. The MFM method was used to study samples with Cu layer thicknesses of 300 nm. It is demonstrated step by step how the application of an external magnetic field leads to remagnetization. An intermediate antiparallel distribution of magnetization in neighboring layers is revealed. The magnitude of the coercive force for an agglomerate of two or three NWs varies between 40-50 Oe, but the magnetization switching field turns out to be about 160 Oe, which is comparable to the coercive force for an array of NWs of this type (180-190 Oe). This demonstrates the role of the NWs' dipole interaction in the matrix.

Sulfonated magnetic graphite carbon nitride solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry for screening malachite green and leucomalachite green in freshwater fish

Malachite green (MG) and its metabolite, leucomalachite green (LMG), exert toxic effects on the human body. The use of these dyes is illegal, but they are still detected in aquatic products. Freshwater fish are aquatic products with the high non-qualified rates. Therefore, the sensitive screening of MG and LMG in freshwater fish is of great importance to ensure the safety of aquatic products. Owing to the low contents of MG and LMG in fish and the complex matrix of actual samples, sample preparation is required before detection to purify impurities and enrich the target compounds. Graphite carbon nitride (GCN), a polymer material composed of C, N, and H, has good chemical and thermal stability, a large specific surface area, and a large number of active sites. It has a wide range of application prospects in adsorption and can be used in food safety testing when compounded with Fe3O4 to form magnetic graphite carbon nitride (MGCN). In this study, sulfonated magnetic graphite carbon nitride (S-MGCN) was prepared by further functionalizing MGCN with sulfonic acid. After characterization by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometry (VSM), a magnetic solid-phase extraction (MSPE) method based on S-MGCN was established to extract MG and LMG from freshwater fish. The targets were screened using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Following sulfonic acid functionalization, S-MGCN showed increased electrostatic interactions based on the MGCN adsorption mechanism, which includes hydrogen bonds and π-π interactions; thus, its adsorption efficiency was significantly improved. The matrix effects were -42.21% and -33.77% before functionalization, -11.40% and -7.84% after functionalization, thus confirming that S-MGCN has significant matrix removal ability. Given that S-MGCN demonstrated excellent efficiency as an MSPE adsorbent, the adsorption conditions for S-MGCN were optimized. The optimal conditions were as follows: adsorbent dosage, 15 mg; adsorption time, 2 min; solution pH, 5; and ionic strength, not adjusted. Under these conditions, the adsorption efficiency of S-MGCN could reach 94.2%. Different organic solvents were used to elute adsorbed MG and LMG, and the desorption efficiency peaked when 1%(v/v) ammonia acetonitrile was used as the elution solvent. The elution volume was also optimized, and a maximum desorption efficiency of 93.2% was obtained when 1 mL of 1%(v/v) ammonia acetonitrile was added to S-MGCN. The limits of detection (LODs) and quantification (LOQs) of the two targets were determined at signal-to-noise ratios (S/N) of 3 and 10, respectively. The LODs and LOQs were 0.075 μg/kg and 0.25 μg/kg, respectively. The linear ranges of the two target compounds were 0.25-20.0 μg/kg with correlation coefficients (r) greater than 0.998. To assess accuracy and precision, we prepared spiked samples at three levels (low, medium, and high) with six parallel samples per level (n=6). The recoveries ranged from 88.8% to 105.9%. The intra- and inter-day relative standard deviations were 5.4%-13.7% (n=6) and 3.3%-11.1% (n=3), respectively. Compared with the national standard method, the proposed method features simpler sample pretreatment procedures, less use of organic reagents (5 mL), and a shorter extraction time (2 min); moreover, the method does not require complicated elution steps, and the eluent can be directly analyzed by UPLC-MS/MS. The test results of actual samples were consistent with those obtained via the national standard method, thus confirming the practical feasibility of the developed method. The proposed MSPE method based on S-MGCN is an efficient and environmentally friendly method that could provide a new methodological reference for the sensitive screening of MG and LMG in actual samples.

Magnetic, dielectric and local electromechanical responses of BiFeO3 nanoparticles prepared by hydroxycarbonate coprecipitation

The results of the BiFeO3 nanoparticles, magnetic, dielectric and local electromechanical responses investigation, obtained by hydroxocarbonate coprecipitation are presented. The weak ferromagnetic response was demonstrated by both vibrating sample magnetometry and magnetic force microscopy. The measurements of the local electromechanical response of the individual nanoparticles demonstrate a presence of the hysteresis loops, which indicate its ferroelectric state.

Magnetic properties of iron-filled hydrogel clusters: a model system for quantitative susceptibility mapping with MRI

Quantitative approaches in clinical Magnetic Resonance Imaging (MRI) benefit from the availability of adequate phantoms. Ideally, the phantom material should reflect the complexity of signals encountered in vivo. In the present study we validate and characterize clusters consisting of sodium-polyacrylate embedded in an alginate matrix that are unloaded or loaded with iron for Quantitative Susceptibility Mapping (QSM), yielding a non-uniform iron distribution and tissue-mimicking MRI properties. Vibrating sample magnetometry (VSM) was used to characterize the phantom material and verify the accuracy of previous MRI-based observations of the QSM-based molar susceptibility (χM). MRI at 14.1 T with high resolution acquisitions was used to determine the size of hydrogel clusters and to further investigate the suitability of the phantom material as a model system for QSM at high field. VSM demonstrated that the iron-solution used for manufacturing the phantoms consisted of ferric iron. The χM of clusters with a constant iron-to-polyacrylate-ratio (8.3 μg/mg) observed with VSM was 50.7 ± 8.0 ppb mM−1 but showed a tendency towards saturation at total iron concentrations >1 mM. On unwrapped and background corrected phase-images obtained with gradient-echo MRI and an isotropic voxel size of 37 μm at 14.1T, the iron-free clusters had a roundish shape and blurry border with an equivalent sphere diameter of 276 ± 230 µm and a QSM of 7 ± 7 ppb. Iron-loading led to strong phase wrapping, necessitating the use of short echo times, or short inter-echo delays below 10 ms at 14.1 T. The equivalent sphere diameter of the iron-loaded clusters was estimated to 400–500 µm as verified using different MRI modalities (spin-echo, inversion recovery, and gradient echo MRI). With a constant iron-to-polyacrylate ratio, the cluster density was 10 mm−3 mM−1 iron. In agreement with previous observations, χM of samples with a constant amount of polyacrylate was 50.6 ± 11.4 ppb mM−1 at 3 T while samples containing clusters with a constant iron-to-polyacrylate-ratio yielded χM = 56.1 ± 6.3 ppb mM−1 at 3T and 55.6 ± 0.7 ppb mM−1 at 14.1 T. In conclusion we found that the molar susceptibility of the proposed model system corresponds to that predicted for ferritin in vivo loaded with 3000 iron atoms. The reproducibility was within 12% across MR scanners, batches, and phantom types and compared well with results obtained with vibrating sample magnetometry.

An efficient and sustainable Pd‐nanomagnetic heterogeneous catalyst for the reduction of nitroarene and environmental pollutant

This study reports the synthesis and characterization of an environmentally friendly, cost‐effective, and sustainable Pd‐heterogeneous catalyst anchored on superparamagnetic silica‐coated iron oxide. The synthesized Pd‐SB/MNP nanomagnetic catalyst was extensively characterized using Fourier transform infrared (FTIR), inductively coupled plasma optical emission spectroscopy (ICP‐OES), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), energy‐dispersive spectrometry (EDS), vibrating sample magnetometry (VSM), field emission scanning electron microscopy (FE‐SEM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and high‐resolution transmission electron microscopy (HR‐TEM). The Pd‐SB/MNP catalyst showed remarkable efficiency in catalyzing the reduction of nitroarene and Cr(VI) under mild reaction conditions using an eco‐friendly solvent. The catalyst exhibits facile recovery through external magnetization, enabling its efficient recycling and reutilization for at least 10 cycles while demonstrating minimal Pd loss, as confirmed by rigorous hot filtration testing and ICP‐OES analysis. These results comply with the industry's prescribed thresholds for permissible levels of residual metallic content. The results suggest that the synthesized Pd‐SB/MNP catalyst holds great potential for various industrial applications.

Magnetic saturation enhancement of gold-capped nickel nanorods

Nickel nanorods (NRs) capped with gold (Au/Ni) were grown into porous anodic aluminum oxide templates and subsequently transferred onto Au/Si (100) substrates. A high dense 2D array of Ni and Au/Ni nanorods was analyzed by vibrating sample magnetometry; it was found that an increase in 14.8% of the magnetic moment following the deposition of Au caps. In order to further investigate this phenomenon, the magnetic distribution of Au/Ni nanorods was studied by off-axis electron holography. The magnetization and induction strengths were evaluated to be 4.7 × 105 A/m and 0.62 T, respectively, which is equivalent to magnetometry measurements of the Ni NR arrays. Remarkably, a vortex state configuration was imaged in the Au segment by the retrieved magnetic phase of the electron holograms under free lens conditions of the transmission electron microscope column. It was concluded that the magnetic distribution in the Au segment is associated with a ferromagnetic coupling with Ni and correlated with the magnetometry measurements.

Designed ultrafine polymer-coated manganese-cobalt ferrite nanoparticles loaded with anticancer drug: efficacy enhancement through host:guest complexation on the polymer surface

Magnetic nanomaterials of different compositions have been examined, focusing on the magnetic field-directed transport of drugs. The size, shape, surface modification and composition variations make every magnetic nanostructure a unique nanocarrier. In this work, we carry out a hydrothermal synthesis of novel manganese-cobalt co-incorporated magnetic ferrite nanoparticles. The particles are characterized using x-ray diffraction, transmission electron microscopy, thermogravimetry and x-ray photoelectron spectroscopy. The size of the nanoparticles is below 10 nm, and they are found to fall under the face-centered cubic system. The nanoparticles are coated with the β-cyclodextrin and folate co-tethered polyethylene glycol. Vibrating sample magnetometry reveals the soft ferromagnetic nature of the nanoparticles with a saturation magnetization value of 28.11 emu g−1 for the coated nanoparticles. The polymer on the nanoparticles allows the loading of the drug feasible, and the encapsulation efficiency is ∼93%. The in vitro release of the drug is monitored and it is observed that the release occurs over 130 h. The cytotoxicity of the free- and camptothecin-loaded manganese-ferrite nanocarrier on breast cancer cell lines is investigated. The IC50 value of the drug-loaded nanocarrier is 2.22 µg mL−1 which is significantly lower than that of the free drug. The drug-encapsulated nanocarrier releases the cargo slowly and continuously and shows increased efficacy, which represents the significance of the nanocarrier. The results present the designed nanomaterial as a suitable anticancer drug vehicle.

Enhanced photocatalytic activity of magnetically recyclable spherical Fe3O4/Cu2O S-scheme heterojunction

ABSTRACT In this study, magnetically recyclable spherical Fe3O4/Cu2O particles comprising S-scheme heterojunctions were prepared by a simple hydrothermal approach using n-type semiconductor Fe3O4 as precursor and p-type semiconductor Cu2O. A Fenton-like system was thus constructed via the addition to Fe3O4/Cu2O of hydrogen peroxide. A rhodamine B (RhB) solution was used to simulate polluted wastewater, and photocatalytic RhB removal experiments were conducted under visible light irradiation. Powder X-ray diffractometry, vibrating-sample magnetometry, nitrogen adsorption–desorption, transmission electron microscopy, and X-ray photoelectron spectroscopy experiments were conducted to characterise Fe3O4 and Fe3O4/Cu2O composite. The band gap of Fe3O4/Cu2O was 1.76 eV, narrower than that of Fe3O4 (2.14 eV). The effects of the pH, sample dosage, hydrogen peroxide concentration, and RhB initial concentration on RhB removal were investigated. According to evidence, under the optimum reaction conditions, the RhB removal rate was 99.4%. The Fe3O4/Cu2O composite exhibited good photocatalytic efficacy even after four cycles of testing. Based on the results of free radical capture experiments, hydroxyl radicals and holes cooperated as main reactive species in the photocatalytic system. The Fe3O4/Cu2O photocatalyst can be easily removed based on magnetism, and it has been proven to be very effective for the degradation of RhB under both UV and visible light irradiation.

Magnetic properties of Cr-doped VO2 thin films in tetragonal phase of rutile and their synchrotron-based electronic structures

The present study is focused on the investigation at 400 K of the tetragonal-rutile phase of Cr-doped VO2 (CVO) thin films grown by pulsed laser deposition. Synchrotron-based x-ray measurements of both the surface-sensitive total electron yield (TEY) and bulk-sensitive total fluorescence yield (TFY) modes were used to investigate the pristine and Cr-doped VO2 (5%, 10%, 20%, and 30% of atomic weight). The structural analysis and purity of the crystalline phase of the as-deposited films are manifested via grazing incidence x-ray diffraction patterns, which confirm the tetragonal-rutile phase. The purity of the phase is also confirmed by the presence of Eg-mode phonons in the Raman spectra and its deconvolution reflects on the oxygen-mediated electronic/vibrational transitional effect. A clear hysteretic behavior obtained through vibrating sample magnetometry strongly suggests the ferromagnetic interaction in the thin films of CVO. The local-electronic property of the samples is examined using x-ray absorption spectroscopy (XAS) in TEY and TFY modes where the difference in the configured helicity photons resulted in the fine spectra of x-ray magnetic circular dichroism (XMCD). XAS and XMCD measurements performed at V L2,3 and Cr L2,3 edges explicitly demonstrate the ferromagnetism in the thin films of CVO. The strong hybridization between V 3d and Cr 3d states with O 2p states is evident from the spectra of the O K-edge, resulting in the onset of the cation-pair formation V5+–Cr3+, which is ferromagnetic by means of double-exchange interaction. The theoretical calculation of density functional theory made upon Vienna ab initio simulation package suggests that CVO is in a mixed state of a ferromagnetic-insulator and a half-metallic ferromagnet.

Immobilization of Ag nanoparticles on NiFe2O4@TiO2@PDA: Multifunctional catalytic action toward the reduction of 4-Nitrophenol and photodegradation of methylene blue and ciprofloxacin

Freshwater, an essential commodity of life, is under threat by the presence of pernicious chemicals, such as 4-nitrophenol (4-NP), organic azo dyes, and colorless antibiotic pollutants, leading to water pollution. It is an absolute necessity to transform these pernicious chemicals into benign compounds to mitigate water pollution and safeguard life on Earth. One such effort in the current work is the development of a recyclable, multifunctional, and heterogeneous NiFe2O4@TiO2@PDA-Ag magnetic nanocatalyst for the reduction of 4-NP to 4-aminophenol (4-AP) and the photocatalytic degradation of methylene blue (MB) (an organic azo dye) and ciprofloxacin (CIP) (a colorless antibiotic pollutant) under irradiation with direct sunlight. Characterization of the developed catalyst was achieved using various spectroscopic and analytical methods (XRD, FTIR & UV–Vis spectroscopy, SEM, TEM, and XPS). The visible light active nature of the catalyst was confirmed by our UV–Vis spectroscopic data. The reduction of 4-NP to 4-AP with 97% conversion was achieved using the catalyst at room temperature in an aqueous medium in the presence of sodium borohydride (NaBH4) at a rate constant of 0.462 min−1. The photocatalytic degradation of MB and CIP was achieved using the catalyst under irradiation with direct sunlight, in which 96.5 and 68% degradation was observed with a degradation rate constant of 0.0483 and 0.0750 min−1 respectively. The presence of a magnetic NiFe2O4 core in the catalyst enables its recovery with the aid of the external magnet, its reusability was assessed and exhibited good efficacy up to five cycles. The magnetic nature of the catalyst was confirmed using vibrating sample magnetometry (VSM). The synthesis of a sole reusable magnetic catalyst suitable for the removal of three toxic pollutants under normal conditions adopting a facile methodology with excellent activity up to five cycles is rare and thus, the findings from the present work provide helpful information in wastewater treatment.

Coprecipitation Methodology Synthesis of Cobalt-Oxide Nanomaterials Influenced by pH Conditions: Opportunities in Optoelectronic Applications

The cobalt oxide (Co3O4) nanomaterials were prepared by coprecipitation synthesis technique by maintaining the pH of the mother solution at 7, 8, and 9. The prepared nanomaterials were subjected to structural and optical characterizations, and the results were examined. The optical absorption spectral studies reveal that the two absorption bands indicate ligand–metal coordination. The photoluminescence spectra contain emission peak at 488 and 745 nm due to size and shape of the synthesized materials. The magnetic nature of the samples was identified from the hysteresis loop traced by vibrating sample magnetometry (VSM). The Fourier transform infrared (FT-IR) spectrum of Co3O4 nanomaterials reveals two sharp bands absorbed in 584 and 666 cm-1. This ascribes to the Co-O and O-Co-O stretching, respectively. As the pH of the solution varied from 7 to 10, the SEM image authenticates the transformation of Co3O4 nanomaterials morphology from spherical to cubic to agglomerated shape. From the UV-Vis spectra, two absorption bands around 473 nm and 762 nm are observed for the materials prepared at pH 7 and 8. But at pH 9, these two peaks were shifted towards higher wavelengths 515 nm and 777 nm. The observed ferromagnetic nature of Co3O4 nanomaterials clearly show the role of surface spins and surface morphology on the magnetic properties of Co3O4 nanomaterials. The cyclic voltammetry (CV) curves show the rectangular type of voltammogram. This is an indication of good charge propagation with the electrodes. The Nyquist plots of Co3O4 nanomaterials have a semicircle in the high frequency region and a vertical line in the low frequency region. The results suggest that Co3O4 is found to be a promising material for the fabrication of light-emitting diodes, solar cells, and optoelectronic devices.

Synthesis, structural and magnetic study of BaFe12O19/CoFe2O4@CoFe2 nanocomposites

Cooperative effects in hybrid nanocomposites are an interesting field of research. The behavior of magnetic nanocomposites is the result of spatial arrangements of phases and their magnetic correlations through exchange and dipolar forces. Understanding these influences is an important task in order to produce magnetic composites with improved properties. In this work, we present a study on the structural and magnetic properties of nanocomposites made of barium hexaferrite (BaFe12O19) coated either with cobalt ferrite spinel (CoFe2O4) or core-shell CoFe2O4@CoFe2 nanoparticles, i.e. BaFe12O19/CoFe2O4 or BaFe12O19/CoFe2O4@CoFe2. The BaFe12O19 (BFO) phase was produced using the ionic coordination reaction technique and then coated with CoFe2O4 (CFO) nanoparticles synthesized by the polyol method. Several concentrations of the BFO and CFO phases were considered. The BFO/CFO samples were reduced in hydrogen gas, where partial reductions of cobalt ferrite give rise to the alloy CoFe2 (CF). Thus, we produced a new nanocomposite of the type BFO/CFO@CF. These samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM) and Mössbauer spectroscopy (ME). The XRD and ME analyzes revealed the presence of the phases BFO and CFO, for the non-reduced nanocomposites, and for the partially reduced nanocomposites we found three phases BFO, CFO and CF. TEM images showed that these phases are structurally coupled. Isothermal remanent magnetization (IRM) and direct current remanent demagnetization (DCD) measurements were done and the analyzes through the Henkel and δm plots were performed, providing information about the nature of the interactions among the phases and their magnetic behavior. The samples BFO/CFO and BFO/CFO@CF with the lowest percentage of BFO (∼7 wt%) showed exchange coupling between the phases while the other samples exhibited predominantly magnetic dipolar interactions.

Magnetic molecularly-imprinted microspheres with a core-shell structure for the extraction of catalpol from both Rehmannia glutinosa Libosch and biological samples

We report on the successful development of a magnetic molecularly imprinted polymer (MMIP) for the separation and detection of catalpol in Rehmannia glutinosa extract and biological samples. Catalpol was used as the template molecule for the MMIPs, which were synthesized using the reverse prediction approach and differential UV–visible spectra to optimize the synthesis conditions. The resulting MMIPs were characterized using techniques including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry, which confirmed their excellent nuclear shell construction and simple rapid magnetic separation.Static and dynamic adsorption experiments were performed to assess the sensitivity, repeatability, and adsorption capacity of the MMIPs. Adsorption capacity was found to be high (59.09 µg/mg). The MMIPs also exhibited strong identification specificity for catalpol analogs (IF = 2.41). Magnetic solid phase extraction (MSPE) was optimized to establish an MSPE-HPLC approach based on the MMIPs. Under ideal conditions, the new method showed excellent determination coefficient (R2 > 0.99) in the ranges of 0.1–1.0 mg/mL and 0.03–0.18 mg/mL for R. glutinosa extract and biological material, respectively, with limits of detection of 5.4 ng/mL and 1.7 ng/mL.The novelty of this research lies in the preparation of magnetic surface MMIPs using a magnetic carrier. These MMIPs exhibit excellent magnetic properties and possess specific adsorption capability for catalpol, enabling rapid separation. They offer advantages such as low cost, high specificity, chemical stability, physical robustness, and recyclability (97.09%–106.53%, 91.32%–100.99%). The application of these polymers in the pretreatment method for determining the catalpol content in R. glutinosa extract and biological samples enhances the extraction efficiency and detection accuracy for catalpol. It eliminates interference and influences from other components in catalpol determination while exhibiting high sensitivity, good enrichment effects, excellent reusability, and a high recovery rate.

Structural, magnetic, and antibacterial activity of the pure, Zn-doped, and Zn-doped/sugar-assisted coprecipitation synthesized semicrystalline Co3O4 compound

Undoped, Zn-doped, and Zn-doped/sugar-assisted semi-crystalline structures of Co3O4 were made by introducing a facile precipitation approach. The synthesized compounds were tested for surface characteristics, magnetic properties, and antibacterial activity. Powder X-ray diffraction (XRD) analysis confirmed semi-crystalline behavior and spinel structure formation in all synthesized compounds. Using scanning electron microscopy (SEM) characterization, microstructure formation along with the large agglomeration of spherical particles, uniform distribution of spherical particles, and spherical-flake-like particle structures were noticed for the pure, Zn-doped, and Zn-doped/sugar-assisted Co3O4 samples, respectively. From the vibration sample magnetometry (VSM), Zn-doped/sugar-assisted Co3O4 was found to have relatively lower saturation magnetization when compared to pure Co3O4 and Zn-doped Co3O4 material. The antibacterial performance of the synthesized compounds against the bacteria Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus) has been tested. The above-mentioned germicidal responses showed a relatively larger inhibition zone for the Zn-doped and Zn-doped/sugar-assisted Co3O4 compared to the undoped Co3O4 sample. The obtained diameter inhibition zone values of all synthesised compounds are comparable to the standard positive and negative control.

Usnic Acid-Loaded Magnetite Nanoparticles-A Comparative Study between Synthesis Methods.

Since cancer is a continuously increasing concern for the general population, more efficient treatment alternatives ought to be developed. In this regard, a promising direction is represented by the use of magnetite nanoparticles (MNPs) to act both as a nanocarrier for the targeted release of antitumoral drugs and as hyperthermia agents. Thus, the present study focused on improving the control upon the outcome properties of MNPs by using two synthesis methods, namely the co-precipitation and microwave-assisted hydrothermal method, for the incorporation of usnic acid (UA), a natural lichen-derived metabolite with proven anticancer activity. The obtained UA-loaded MNPs were thoroughly characterized regarding their morpho-structural and physicochemical properties through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS) and zeta potential, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). Results demonstrated the formation of magnetite as the unique mineralogical phase through both types of synthesis, with increased uniformity regarding the drug loading efficiency, size, stability, and magnetic properties obtained through the microwave-assisted hydrothermal method. Furthermore, the cytotoxicity of the nanostructures against the HEK 293T cell line was investigated through the XTT assay, which further proved their potential for anticancer treatment applications.

Cobalt Ferrite Nanoparticles Capped with Perchloric Acid for Life-Science Application

Among the modern oncological therapies, one of the most promising is based on tumor hyperthermia with magnetic nanoparticles resulting from the crystallization of iron and cobalt oxides. We synthesized core–shell magnetic nanoparticles of perchlorate-CoxFe3−xO4 (x = 0; 0.5; 1.0) via the co-precipitation method and stabilized them in aqueous suspensions. Fine granulation of the dispersed ferrophase was revealed by Transmission Electron Microscopy and Dynamical Light Scattering, with FTIR data detailing the surface-interaction phenomena. X-ray diffractometry revealed specific crystallization features of inverse spinel lattice, providing crystallite size and lattice parameters dependent on the cobalt content. The results of the Vibrating Sample Magnetometry investigations indicated that cobalt doping has reduced the magnetic core size and increased the nanoparticle dimension, which could be the result of crystallization defects at the nanoparticle surface related to the presence of cobalt ions. A mathematical model was applied with a focus on the quantitative description of the temperature distribution around magnetic nanoparticles. Further development of our research will consider new cobalt ferrite nanoparticles with new cobalt contents and different organic coatings to contribute to their biocompatibility and stability in aqueous suspensions, as required by administration in living organisms.

SO3H-Functionalized Epoxy-Immobilized Fe3O4 Core-Shell Magnetic Nanoparticles as an Efficient, Reusable, and Eco-Friendly Catalyst for the Sustainable and Green Synthesis of Pyran and Pyrrolidinone Derivatives.

A SO3H-functionalized epoxy-immobilized Fe3O4 core-shell magnetic nanocatalyst was prepared through a simple three-step procedure, and it was identified by various analyses such as Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential thermal gravity (DTG), Brunauer-Emmett-Teller (BET) analysis, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM), and powder X-ray diffraction (PXRD). BET analysis showed that the as-prepared nanocatalyst was synthesized with a mesoporous structure and high specific area (35.45 m2 g-1). The TEM image clearly showed that the particle size distribution was in the range of 47-65 nm. The designed magnetic nanocatalyst was used successfully in the synthesis of pyran derivatives via the reaction of dimedone, malononitrile, and various aromatic aldehydes and synthesis of pyrrolidinone derivatives via the reaction of various aromatic aldehydes, aniline, and diethyl acetylenedicarboxylate. The nanocatalyst was simply isolated from the reaction mixture utilizing an external magnet and reused several times according to the model reactions without significant loss in its efficiency.

Impact of cobalt doping on magnetic and structural properties in Ce1−xCoxO2 (x = 0.1, 0.2 and 0.3) ceramics synthesized by combustion method

In this investigation, cobalt doped ceria nanopowders, Ce1-xCoxO2 (x = 0.1, 0.2 and 0.3mol.%) were synthesized by citrate–nitrate auto-combustion method at 500 °C in an open furnace. The prominent X-ray diffraction pattern peaks corresponding to the crystallographic planes (1 1 1), (2 0 0), (2 2 0), (3 1 1), (2 2 2), (4 0 0) and the cell parameters confirm the cubic fluorite crystal structure of the ceria with the help of powder diffraction standard (JCPDS card No.00-034-0394). The UV–Visible absorption due to the charge transfer of O2− → Ce2+ and other functional groups were studied by UV–Visible and FT-IR spectroscopic analyses. The visible light emission (wavelength of 420 nm and 520 nm are corresponding to the defect levels of the O 2p and Ce 4f bands) due to oxygen and other vacancies were confirmed by photoluminescence spectroscopy. Energy band gap (Eg) of the Ce0.9Co0.1O2, Ce0.8Co0.2O2 and Ce0.7Co0.3O2 was found to be 1.423 eV, 1.375 eV and 1.332 eV, respectively. The porosity, agglomeration, particles size, shape and distribution of the synthesized nanoparticles were analyzed by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM). The energy dispersive X-ray spectroscopy (EDX) confirms the presence of constituent elements of Ce1-xCoxO2 such as Ce, Co, and O. The existence of weak ferromagnetism and its variation due to cobalt concentration were studied by vibrating sample magnetometry (VSM) at room temperature.