Coated Magnetite Nanoparticles Research Articles

Retraction Note: Synthesis and characterization of uncoated and coated magnetite nanoparticles and use of their peroxidase like activity for phenol detection

Retraction Note: Synthesis and characterization of uncoated and coated magnetite nanoparticles and use of their peroxidase like activity for phenol detection

Preparation of berberine magnetic nanoparticles and their inhibition of human gastric cancer BGC-823 cells

A new drug delivery system loaded with the drug berberine on carboxymethyl chitosan-coated magnetic nanoparticles (Fe3O4@CMCS-BBR) was prepared and characterized through x-ray diffraction, Fourier transform-infrared spectroscopy, a vibrating sample magnetometer, and transmission electron microscopy. By comparing the size of the uncoated nanoparticles (39.26 nm) and the size of the coated magnetite nanoparticles (73.75 nm), it was found that with the CMCS coating on the magnetite nanoparticles, the dispersion of the nanoparticle improved. The optimum pH testing showed a higher drug encapsulation of 51.23% and drug loading of 17.10% at a pH of 5.5 because of the better interaction of the NH3+ group with the negative functional groups of the CMCS. Furthermore, 85.89% of the drug was released within 72 h. The CCK-8 test results showed that Fe3O4@CMCS-BBR magnetic nanocomposites had good biocompatibility with gastric cancer BGC-823 cells and that Fe3O4@CMCS-BBR effectively inhibited the proliferation of cancer cells. The magnetic experimental results showed that Fe3O4@CMCS-BBR had good responsiveness to external magnetic fields and aggregated in the presence of a magnetic field. The results of targeting experiments showed that fluorescein isothiocyanate emitted a strong yellowish fluorescence in cells, which became stronger over time, and the killing effect on cancer cells became greater. The apoptosis results showed that the apoptosis rate induced by the magnetic nanodrug was 54.90%, indicating that the drug had a promoting effect on the apoptosis of BGC-823 cells.

RETRACTED ARTICLE: Synthesis and characterization of uncoated and coated magnetite nanoparticles and use of their peroxidase like activity for phenol detection

RETRACTED ARTICLE: Synthesis and characterization of uncoated and coated magnetite nanoparticles and use of their peroxidase like activity for phenol detection

Tuning the heat dissipated by polyacrylic acid (PAA)-coated magnetite nanoparticles under alternating magnetic field for hyperthermia applications

Tuning the heat dissipated by polyacrylic acid (PAA)-coated magnetite nanoparticles under alternating magnetic field for hyperthermia applications

Polyethylene Glycol (PEG) Coated Magnetite Nanoparticles Prepared by Sol-Gel Method for Biotechnology Applications

Polyethylene glycol (PEG) coatings are developed for magnetite nanoparticles (NPs). The magnetic properties of superparamagnetic type, magnetite Fe3O4 nanoparticles are suitable for biosensing applications. Magnetic NPs were prepared by Co-precipitation method and oven dried. Using a Transmission Electron Microscope (TEM) and X-Ray Diffractometer (XRD), nanoparticles size and composition were found, including the presence of Fe3O4 peak. The magnetic properties are influenced by electron environments of the Fe3+ ions within the iron oxide structure. The magnetic properties were measured by Vibrating Sample Magnetometer (VSM), thus, the results of Fe3O4 NPs exhibited a high magnetic saturation (Ms) of 61.31 emu/g. In the case of PEG coated MNPs, confirmed by Fourier Transform Infrared Spectroscopy (FT-IR), a reduced Ms of 40.00 emu/g, which decreased further following surface modification with 3-aminopropyl triethoxysilane (NH2) to 36.77 emu/g. The resulting size range of NPs of pure Fe3O4 NPs was 5-50 nm. In comparison, the PEG coated NPs were larger, 10-100 nm. In the part of protein binding and separation from solutions of bovine serum albumin (BSA) where investigated. This process will be beneficial to developing low cost sensors for biomolecules and biotechnologies in the future.

Heterogenous electro-Fenton degradation of sulfamethoxazole on a polyethylene glycol-coated magnetite nanoparticles catalyst

We report the preparation and application of poly (ethylene) glycol (PEG) coated magnetite nanoparticles (MNPs) catalyst for the heterogeneous electro-Fenton (HEF) degradation of sulfamethoxazole in real wastewater PEG-coated MNPs of four MNP:PEG ratios were synthesised using the co-precipitation method. The synthesised MNP were characterised using FTIR, XRD, EDX, TEM, and CHN elemental analysis. It was observed that the coating of MNP with PEG influences the nanoparticle size, agglomeration tendencies and catalytic efficiency of MNPs properties in the HEF degradation process. A 1:1 optimal MNP:PEG catalyst yielded 91% sulfamethoxazole degradation and 48% total organic carbon removal in 60 min, which is an improvement of 11% over degradation with the uncoated MNP. The PEG-coated MNP showed higher stability in 10 consecutive reaction cycles, reduced leaching, and improved performance at a lower dosage and broader pH range than the uncoated MNPs. These results show that coating MNP with PEG enhances HEF catalytic performance in the degradation of sulfamethoxazole in wastewater.

Stable silicone oil based ferrofluids with well low-temperature fluidity applied to magnetic fluid seal

Stable silicone oil based ferrofluids with high magnetization and low-temperature fluidity have been successfully synthesized. The ferrofluids containing surfactant coated magnetite nano particles with average diameters of 10 nm could maintain stable for more than 2 months. Silicone oil based ferrofluids could reach a saturated magnetization of 24.6 emu/g, which ensures them to be easily controlled by the magnetic fields. Silicone oil based ferrofluids could maintain their fluidity at −40 °C while the LAN15 (engine oil) based ferrofluids could not. The property of low- temperature fluidity is systematically explained by the magneto-rheological experiments. This outstanding property of low-temperature fluidity ensures the silicone oil based ferrofluids a promising candidate material for applications in magnetic fluid seal. Herein, the magnetic rotary sealing performed by different ferrofluids at low temperature are systematically characterized. As result, the silicone oil based ferrofluids have lower starting torque and higher sealing pressure endurance compared to LAN15 based ferrofluids at −40 °C. Based on our experimental results, the theoretical analysis and numerical simulation results systematically explained the advantages silicone oil based ferrofluids have on low-temperature magnetic fluid seal.

Colloidal stability and rheological properties of bio-ferrofluids of polymer-coated single-core and multi-core nanoparticles

The polymethacrylic acid (PMAA)-coated magnetite nanoparticles with single and multi-cores were prepared by the emulsifier-free emulsion polymerization of methacrylic acid (MAA) monomers. X-ray diffraction analysis (XRD), Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM) were used to identify the nanoparticles and the polymer layer. The coated particles have spherical shapes. The single core diameter is 6.6 nm, and the multi-core diameter is 33.8 nm, with the number of cores in a particle of 131. The PMAA layer thickness is around 4 nm for both coated particles. This polymer layer enhances nanoparticles' dispersion ability while retaining their magnetic properties much higher than in other studies. The coated multi-core particles show excellent dispersion stability. The aggregation rate of these particles is hundreds of times lower than that of single-core particles. All the nanofluids exhibit shear-thinning behavior without and with an external magnetic field. The field-dependent viscosity agrees with the theory regarding the interaction parameter λ. However, the magneto-viscous of the magnetic fluids here are much smaller than comparable bio-ferrofluids.

Interaction between dirhodium(II) tetraacetate and PAMAM dendrimer grafted onto magnetite nanoparticles: Effects on magnetic properties

In this study, we report on fabrication and characterization of a novel magnetic nanocarrier based on association of magnetite nanoparticles (NPs) with poly(amidoamine) (PAMAM) dendrimers loading dirhodium(II) tetraacetate complex (DiRh(II)). The pristine magnetite NP was coated with ATPS (3-aminopropyltriethoxysilane). The interaction between PAMAM dendrimer and DiRh(II) and its effects on magnetic properties were investigated. The magnetite spinel phase is confirmed via x-ray diffraction (XRD) and Raman spectroscopy data analysis. A mean crystallite size of 9.5 ± 0.3 nm of magnetite particles is assessed from XRD data, which is close to the values obtained via dynamic light scattering (DLS) and transmission electron microscopy micrographs. Our findings strongly suggest that the Rh(II) ions interact with lone electron pairs of nitrogen atoms in amide-II and primary amines of PAMAM surface-terminated moieties. The onset of an absorption peak at 283 nm in DiRh(II) containing sample, assigned to σRh-L→σ∗Rh-Rh electronic transition, revealed a direct interaction between Rh(II) ions and L moieties of PAMAM dendrimer. Magnetization results indicate that the presence of DiRh(II) attached to PAMAM dendrimer leads to the strong weakening of magnetic dipole–dipole interactions in ATPS- and ATPS + PAMAM coated magnetite nanoparticles.

Effecting pattern study of SO2 on Hg0 removal over α-MnO2 in-situ supported magnetic composite

α-MnO2 was in-situ supported onto silica coated magnetite nanoparticles (MagS-Mn) to study the adsorption and oxidation of Hg0 as well as the effecting patterns of SO2 and O2 on Hg0 removal. MagS-Mn showed Hg0 removal capacity of 1122.6 μg/g at 150 °C with the presence of SO2. Hg0 adsorption and oxidation efficiencies were 2.4% and 90.6%, respectively. Hg0 removal capability deteriorated at elevated temperatures. Surface oxygen and manganese chemistry analysis indicated that SO2 inhibited the Hg0 removal through consumption of adsorbed oxygen and reduction of high valence manganese. This inhibiting effect was observed to be counteracted by O2 at lower temperatures. O2 tended to compete with SO2 for active sites and further create additional adsorbed oxygen sites for Hg0 surface reaction via surface dissociative adsorption rather than replenish the active sites consumed by SO2. The high valence manganese was also preserved by O2 which was essential to Hg0 oxidation. The intervention of O2 in the inhibition of SO2 on Hg0 removal was weakened at temperatures higher than 250 °C. Aa a result, Hg0 tends to be catalytic oxidized in the condition of low reaction temperatures and with the presence of O2 over α-MnO2 oriented composites.

Comparative study on effects of pH, electrolytes, and humic acid on the stability of acetic and polyacrylic acid coated magnetite nanoparticles

The poor colloidal stability of magnetite nanoparticles (MNPs) limits their mobility and application, so various organic coatings (OCs) were applied to MNPs. Here, a comparative study on the colloidal stability of MNPs coated with acetic (HAc) and polyacrylic acids (PAA) was conducted under varied pH (5.0–9.0) in the presence of different concentrations of cations and anions, as well as humic acid (HA). Comparing the effects of various cations and anions, the stability of both HAc/PAA-MNPs followed the order: Na+ > Ca2+and PO43− > SO42− > Cl−, which could be explained by their adsorption behaviors onto HAc/PAA-MNPs and the resulting surface charge changes. Under all conditions even with more anion adsorption onto HAc-MNPs (0.14–22.56 mg/g) than onto PAA-MNPs (0.04–18.34 mg/g), PAA-MNPs were more negatively charged than HAc-MNPs, as PAA has a lower pHIEP (2.6 ± 0.1) than that of HAc (3.7 ± 0.1). Neither the HAc nor PAA coatings were displaced by phosphate even at considerably high phosphate concentration. Compared with HAc-MNPs, the stability of PAA-MNPs was greatly improved under all studied conditions, which could be due to both stronger electrostatic and additional steric repulsion forces among PAA-MNPs. Besides, under all conditions, Derjaguin-Landau-Verwey-Overbeek (DLVO) explained well the aggregation kinetic of HAc-MNPs; while extended DLVO (EDLVO) successfully predict that of PAA-MNPs, indicating steric forces among PAA-MNPs. The aggregation of HAc/PAA-MNPs was all inhibited in varied electrolyte solutions by HA (2 mg C/L) addition. This study suggested that carboxyl coatings with higher molecular weights and pKa values could stabilize MNPs better due to stronger electrostatic and additional steric repulsion. However, in the presence of HA, these two forces were mainly controlled by adsorbed HA instead of the organic pre-coatings on MNPs.

Dye Elimination by Surface-Functionalized Magnetite Nanoparticles: Kinetic and Isotherm Studies

In the present manuscript, uncoated and citric acid-coated magnetic nanoparticles were synthesized and characterized using various techniques. The manuscript mainly focuses on the adsorption study of the citric acid-modified magnetic nanoparticles for dye adsorption from the solution. The effect of several factors, including adsorbent amount, adsorption time, and dye solution concentration, were examined. Additionally, kinetic and isotherm studies confirmed that the adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm model. The desorption study was also scrutinized. The coated magnetite nanoparticles show better adsorption capacity than uncoated magnetite nanoparticles.

Development of novel Core–shell impregnated polyuronate composite beads for an eco-efficient removal of arsenic

Arsenic (As) can geogenically and anthropogenically contaminate the potable water resources and undoubtedly reduces its availability for human consumption. To circumvent this predicament, present study focuses on the development of a novel biosorbent by impregnating calcium cross-linked polyuronate (alginate) beads (CABs) with bilayer–oleic coated magnetite nanoparticles (CAB@BOFe) for As(V) removal. Initially, the system parameters (i.e., adsorbents dose (0.1– 3.0 g L–1), pH (4.0–13), reaction times (0–180 min) and sorbate concentrations (10–150 µg L–1)) were optimized to establish adsorbent at the lab-scale. CAB@BOFe had higher monolayer (ad)sorption capacity (∼62.5 µg g−1, 120 min) than CABs (∼17.9 µg g−1, 180 min). Electrostatic/Ion-dipole interactions and surface-complexation mechanisms mediated As(V) sorption onto CAB@BOFe mainly obeyed Langmuir isotherm (R2 ∼ 0.9) and well described by intraparticle diffusion process. Furthermore, it demonstrated an excellent arsenate removal performance from the single/multiple anionic contaminants simulated water samples which supported its prospective field applicability.

A flexible visual detection of calcium peroxide in flour employing enhanced catalytic activity of heterogeneous catalysts binary copper trapped silica-layered magnetite nanozyme

Herein, a novel heterogeneous nanozyme with peroxidase (POD)-like activity was conducted to achieve ultrasensitive visual detection of calcium peroxide (CaO2) in flour by the assembly of binary copper-trapped mesoporous silica layer coated magnetite nanoparticles (Fe3O4 @SiO2 @CuO NPs). The prepared nanozymes were characterized using HRTEM, SEM, FT-IR, XRD, DLS, and EIS, which displayed a dispersed core-shell structure with a uniform diameter of approximately 100 nm. The nanozymes exhibited remarkable and stable POD-like activity in a wide range of pH values, incubation temperature, and reaction time, and the optimum catalytic activity was obtained at pH 3.6, 37 °C, and 10 min. The quantification range of CaO2 of this method is 0.1–5 mM with a limit as low as 5.6 × 10−3 mM, and it is not affected by multiple interferences. In conclusion, this detection method is sensitive, stable, low-cost, and simple to operate, so it has broad application prospects in the detection of food additives such as CaO2.

Synthesis and Characterization of Silica Coated Magnetite Nanoparticle Clusters for Viral RNA Extraction

Magnetite nanoparticles or iron oxide nanoparticles are the most explored magnetic nanoparticles till recent times, particularly due to their attractive properties for biomedical applications such as viral RNA extraction. The physical and chemical properties of magnetite nanoparticles and their clusters largely depend on the synthesis method and chemical structure. Co-precipitation method was used to synthesize magnetite nanoparticles at varying process parameters. The nanoparticles were coated with silicon-oxide using Stober method at different deposition durations. These particles were characterized by X-Ray Diffraction, Scanning Electron Microscopy, vibrating sample Magnetometer and PCR testing to study the phases formed, morphology, size, magnetic properties and RNA extraction efficiency. The synthesized magnetite nanoparticles were in the range of 10 to 100 nm; suitable for super-para-magnetic behavior. The maximum saturation magnetization achieved for synthesized paramagnetic beads was 56 emu and RNA extraction efficiency was more than 80% as compared to commercial beads.

Substituted Poly(Vinylphosphonate) Coatings of Magnetite Nanoparticles and Clusters

Magnetite nanoparticles and clusters of nanoparticles have been of Increasing scientific interest in the past decades. In order to prepare nanoparticles and clusters that are stable in suspension, different coatings have been used. Phosphates and phosphonates are a preferred anchoring group for the coating of magnetite nanomaterials. However, poly(vinylphosphonates) have rarely been used as a coating agent for any nanoparticles. Here, poly(methylvinylphosphonate) and other substituted polyvinylphosphonates are described as new coatings for magnetite nanoparticles and clusters. They show great stability in aqueous suspension. This is also the first time phosphonate-coated magnetite clusters have been synthesized in a one-pot polyol reaction. The coated magnetite nanoparticles and clusters have been characterized by TEM, EDX, FTIR, magnetization measurement, XRD as well as XPS. It has been shown that substituted vinylphosphonates can be easily synthesized in one-step procedures and as a polymeric coating can imbue important properties such as stability in suspension, tight binding to the particle surface, the ability to be further functionalized or to tightly adsorb metal ions. For the synthesis of magnetite clusters the cluster formation, polymerization and coating are done in a one-pot reaction and the resulting magnetite clusters show a higher amount of phosphonate coating than with a three-step procedure including a ligand exchange.

A nanocomposite of silica coated magnetite nanoparticles and aniline-anthranilic acid co-polymeric nanorods with improved stability and selectivity for fluoroquinolones dispersive micro solid phase extraction

Adsorbents composed of polyaniline nanostructures or their derivatives immobilized on magnetic nanoparticles had gained increasing interest for application in dispersive micro-solid phase extraction. However, reproducible binding between polymeric PANI nanopaterials and magnetic nanomaterials are still a challenging task. Furthermore, other challenges are the enhancement of physical and chemical stability of adsorbent magnetic nanoparticles as well as improvement of polymeric PANI nanoparticles selectivity towards target analytes. This work described the reproducible preparation of a nanocomposite of aniline-anthranilic acid co-polymeric nanorods with silica coated magnetite nanoparticles by physical mixing of its basic components. The prepared nanocomposite had proven stability against chemical and atmospheric attack. The formed nanocomposite in this work had advantages regarding stability and selectivity towards fluoroquinolones as compared with analogues prepared from polyaniline polymers and/or uncoated magnetite nanoparticles. The selectivity of the formed adsorbent was further optimized for microextraction of four fluoroquinolone antibacterial agents. The application of the prepared nanocomposite was exemplified in microextraction of the studied fluoroquinolones from spiked milk samples to enable their detection down to their stated maximum residue limits.

Synthesis of magnetite nanoparticles coated with polyvinyl alcohol for hyperthermia application

One of the main challenges in hyperthermia treatment is how to improve the heating performance of nanoparticles with high specific loss power (SLP). To tackle this challenge, magnetite nanoparticles (MNPs) and coated magnetite nanoparticles with polyvinyl alcohol (PVA@MNPs) were fabricated via ultrasonic-assisted coprecipitation technique. The obtained nanoparticles were characterized by using FT-IR, TEM, TGA, XRD, ICP-OES, DLS, zeta potential, VSM and UV–Vis spectroscopy. The self-heating properties of the MNPs and PVA@MNPs were studied under alternating magnetic strength, frequency and induction time. MNPs and PVA@MNPs showed that the nanoparticles have a nearly spherical shape ranging between 12.3 ± 3.2 and 10 ± 2.5 nm, respectively. The higher value of zeta potentials of PVA@MNPs (− 11.49 mV) implies that the nanoparticle may show good stability in aqueous solutions. The magnetization saturation values were 41.98 and 45.08 emu g−1 for MNPs and PVA@MNPs, respectively. The prepared nanoparticles showed small coercivity and a remanence magnetization due to the soft magnetic nature of the prepared nanoparticles. The highest SLP value was 163.81 W g−1 for PVA@MNPs, while the lowest SLP value was 4.84 W g−1 for MNPs under the same magnetic field condition. The presence of PVA shell improved the particle stability and the magnetization for PVA@ MNPs. This successfully caused an improvement in the heating performance and magnetic hyperthermia as well. These features make the prepared PVA@MNPs in this study applicable as hyperthermic agents for biomedical applications.

Transport and Retention of Poly(Acrylic Acid-co-Maleic Acid) Coated Magnetite Nanoparticles in Porous Media: Effect of Input Concentration, Ionic Strength and Grain Size.

Understanding the physicochemical factors affecting nanoparticle transport in porous media is critical for their environmental application. Water-saturated column experiments were conducted to investigate the effects of input concentration (Co), ionic strength (IS), and sand grain size on the transport of poly(acrylic acid-co-maleic acid) coated magnetite nanoparticles (PAM@MNP). Mass recoveries in the column effluent ranged from 45.2 to 99.3%. The highest relative retention of PAM@MNP was observed for the lowest Co. Smaller Co also resulted in higher relative retention (39.8%) when IS increased to 10 mM. However, relative retention became much less sensitive to solution IS as Co increased. The high mobility is attributed to the PAM coating provoking steric stability of PAM@MNP against homoaggregation. PAM@MNP retention was about 10-fold higher for smaller grain sizes, i.e., 240 µm and 350 µm versus 607 µm. The simulated maximum retained concentration on the solid phase (Smax) and retention rate coefficient (k1) increased with decreasing Co and grain sizes, reflecting higher retention rates at these parameters. The study revealed under various IS for the first time the high mobility premise of polymer-coated magnetite nanoparticles at realistic (<10 mg L−1) environmental concentrations, thereby highlighting an untapped potential for novel environmental PAM@MNP application usage.

Aggregation of varied organic coated magnetite nanoparticles: Adsorbed mass and thickness of coatings and interactions with natural organic matter

Magnetite nanoparticles (MNPs) with varied organic coatings (OCs) which improved their stability have broad environmental applications. However, the adsorbed amounts and layer thickness of varied OCs onto MNPs during the synthesis were generally not or poorly characterized, and their interactions with natural organic matter (NOM) were still in progress. In this study, acetic (HAc), citric (CA), and polyacrylic acid (PAA) were selected as model OCs, the adsorption behaviors of OCs on MNPs were characterized under varied aqueous C/Fe ratios, and the aggregation behaviors of MNPs with varied OCs (OC-MNPs) at neutral pH (7.0 ± 0.2) with NaCl (5–800 mM) in the presence/absence of NOM were systematically investigated. Under low aqueous C/Fe ratio, the adsorbed amounts of model OCs as –COOH/Fe ratio followed the order: CA ≈ PAA > > HAc. With high aqueous C/Fe ratio, the maximum adsorbed masses of OC-MNPs were similar. The adsorbed layer thicknesses of OC-MNPs were thoroughly characterized using three different methods, all showing that the adsorbed layer of PAA was thicker than that of CA and HAc. Derjaguin–Landau–Verwey–Overbeek (DLVO) and extended DLVO (EDLVO) calculations showed that electrostatic and van der Waals forces were dominant for CA-MNPs and HAc-MNPs stabilization; while steric repulsion played major roles in stabilizing PAA-MNPs, probably due to a thicker PAA layer. In the presence of NOM, stability behaviors of all OC-MNPs were similar, ascribing to the much greater amounts of NOM adsorbed than the OCs, causing greater steric repulsion. This study provides new mechanistic insights which could help better understand the effects of varied OCs on MNPs' colloidal stability.