Acid-coated Fe3O4 Nanoparticles Research Articles

PAMAM-modified citric acid-coated magnetic nanoparticles as pH sensitive biocompatible carrier against human breast cancer cells

Denderimer-modified magnetic nanoparticles are a promising drug delivery nanosystem which can improve the therapeutic efficacy of chemotherapy drugs and can also be beneficial as magnetic resonance (MR) images contrast agent. The present study introduces the preparation and characterization of the potential therapeutic efficiency of curcumin (CUR)-loaded denderimer-modified citric acid coated Fe3O4 NPs. Polyamidoamine (PAMAM, generation G5) was used to encapsulate citric acid coated Fe3O4 nanoparticles. The successful preparation of CUR-loaded nanocarriers were confirmed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM) techniques. The loading capacity and encapsulation efficiency of CUR molecules were 12 ± 0.03% and 45.58 ± 0.41%, respectively. The anticancer effect of void CUR and CUR-loaded nanocarriers were compared to each other by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on treated MCF-7 cell line. It can be concluded that application of nanoparticles can be more effective strategy for controlled and slow release of CUR in human breast cancer treatment.

Ferrofluid synthesis using oleic acid coated Fe3O4 nanoparticles dispersed in mineral oil for heat transfer applications

Ferrofluids are stable dispersion of iron oxide nanoparticles in a carrier fluid which find potential applications in heat transfer. Fe3O4 nanoparticles of mean size in the range of 5–10 nm were synthesized using conventional co-precipitation method. This work deals with the synthesis of ferrofluids using mineral oil as a carrier fluid and oleic acid coated Fe3O4 nanoparticles as dispersed phase. Morphology (shape and size) and crystallinity of the synthesized nanoparticle is captured using TEM and XRD. Oleic acid coating on nanoparticle is probed using FTIR for confirming the stability of ferrofluid. Thermal properties of mineral oil based ferrofluid with varying concentration of nanoparticles are evaluated in terms of thermal conductivity. It was found that the thermal conductivity of ferrofluid increases upto 2.5% (w/v) nanoparticle loading, where a maximum enhancement of ∼51% in thermal conductivity was recorded as compared to the base fluid.

Silica Sulfuric Acid-coated Fe3O4 Nanoparticles as a Highly Efficient and Reusable Solid Acid Catalyst for the Green Synthesis of 2,3- Dihydroquinazolin-4(1H)-ones under Solvent-free Conditions

Silica Sulfuric Acid-coated Fe3O4 Nanoparticles as a Highly Efficient and Reusable Solid Acid Catalyst for the Green Synthesis of 2,3- Dihydroquinazolin-4(1H)-ones under Solvent-free Conditions

Rapid extraction of uranium from sea water using Fe3O4 and humic acid coated Fe3O4 nanoparticles

Uranium is one of the most toxic elements present in the environment and a number of methods have been developed for its extraction. Herein we have demonstrated a new method using magnetic nanoparticles (NPs) that can be used for uranium extraction from water and sea water matrix. Fe3O4 and humic acid (HA) coated Fe3O4 NPs with different amount of HA coating were synthesized and uranium sorption from water and sea water matrix was demonstrated. It was observed that sorption increases with increase in amount of HA coating. NPs settlement in presence of magnetic field was monitored where only bare Fe3O4 and Fe3O4/HA 1 NPs settles while no settlement was observed for Fe3O4/HA 2 and Fe3O4/HA 3 NPs. Considering both sorption and particle separation from the matrix Fe3O4/HA 1 NPs are the best among synthesized ones with maximum sorption capacity of 10.5mg of U/g of NPs. The results presented here reveal the exceptional potential of magnetic NPs and functionalized magnetic NPs for environmental remediation of uranium and to extract uranium from sea water on which to the best of our knowledge no report is available till now.

Ionic liquid enhanced magnetic solid-phase extraction of phthalate esters in food samples with oleic acid coated-Fe3O4 nanoparticles prior to HPLC

ABSTRACTA novel method based on ionic liquid enhanced magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography (HPLC) for the separation/analysis of phthalate esters (PAEs) in food samples was established. 1-hexyl-3-methylimidazoliu-hexafluorophosphate ([C6MIM][PF6]) was used to coat oleic acid Fe3O4 nanoparticles with core–shell structures to prepare MSPE agents (Fe3O4@OA@IL). The main parameters affecting the extraction efficiency of PAEs were studied. Under the optimal conditions, the calibration curves were linear in the range of 5–5000 ng mL−1 (R2 = 0.9972–0.9998) of four PAEs. The limit of detections (LODs) and relative standard deviations (RSDs, n = 5) of the method were 1.27–2.95 ng mL−1 and 3.9–5.3%, respectively.

Large-Scale, Facile Transfer of Oleic Acid-Stabilized Iron Oxide Nanoparticles to the Aqueous Phase for Biological Applications.

Fe3O4 nanoparticles synthesized via thermal decomposition in the organic phase have attracted tremendous research interest because of their unique morphology, size dispersion, and crystallinity. However, their poor water dispersibility strongly limited their development in biomedical applications. Therefore, a phase-transfer strategy through which hydrophobic nanoparticles with good performance in the aqueous phase can be obtained is an extremely critical issue. Herein, we present a large-scale, facile, highly efficient strategy for the phase transfer of oleic acid-coated Fe3O4 nanoparticles via a reverse-micelle-based oxidative reaction. The reverse micelle system improves the efficiency of the interface oxidative reaction and prevents the aggregation of nanoparticles during the reaction, facilitating the transfer of Fe3O4 nanoparticles from the organic phase to the aqueous phase. The transferred Fe3O4 nanoparticles are used as a T2 contrast agent to perform magnetic resonance imaging of CNE2 cells (nasopharyngeal carcinoma cell line). In addition, the free carboxyl groups on the surface of transferred nanoparticles can also be programmed to permit the conjugation of other molecules, in turn allowing nanoparticles to be extended in biological targeting or biological recognition applications. Therefore, this strategy offers a promising platform for the large-scale, highly efficient phase transfer of oleic acid-capped nanoparticles and may become a new paradigm to promote the development of diverse nanoparticles for widespread biomedical applications.

Nonanoic Acid-Coated Magnetite Nanoparticles for Separation and Preconcentration of Lead and Copper in Tobacco Samples prior to Flame Atomic Absorption Spectrometry Determination

A new method using nonanoic acid-coated magnetic Fe3O4 nanoparticles as adsorbent has been developed for the single-step extraction and preconcentration of lead and copper in tobacco samples. Transmission electron microscopy and X-ray diffraction spectrometry were used to characterize the adsorbent. The experimental parameters affecting extraction efficiency, including amount of nanoparticles, volume of chelating reagents, sample pH, ultrasonic time and desorption conditions were investigated. The analytes desorbed from nanoparticles were determined by flame atomic absorption spectrometry. Under the optimum conditions, good linearity was obtained in the range of 2-400 µg L-1 for copper and 5-800 µg L-1 for lead (r > 0.998, p < 0.05). The limits of detection for copper and lead were 0.2 and 0.5 µg L-1, with enrichment factors of 45 and 52, respectively. The method was successfully employed to tobacco sample analysis and got excellent recoveries between 89.2 and 100.7% with relative standard deviations (n = 6) of 4.5-5.9%.

Chitosan- and dehydroascorbic acid-coated Fe3O4 nanoparticles: preparation, characterization and their potential as draw solute in forward osmosis process

Forward osmosis (FO) is a natural osmosis process that has attracted a significant attention due to its many advantages. However, the development of FO process depends on the development of proper draw solutions. In this work, chitosan (CS)-coated Fe3O4 nanoparticles and dehydroascorbic acid (DHAA)-coated Fe3O4 nanoparticles were successfully synthesized by co-precipitation method and their performance as draw solutes was investigated for application in FO systems. CS and DHAA could improve the surface hydrophilicity of the Fe3O4 nanoparticles. The synthesized nanoparticles were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM) which the results presented a small size, crystalline morphology and high magnetization value for their structure as well as a good dispersion in water. Cellulose triacetate/cellulose acetate (CTA/CA)-based membranes were also prepared by immersion precipitation and used as FO membranes. The synthesized FO membranes were characterized by FESEM. The performance evaluation of synthesized nanoparticles revealed that the water flux of Fe3O4 nanoparticles capped with DHAA was higher than that of the chitosan-coated Fe3O4 nanoparticles. At the end of the process, the Fe3O4 nanoparticles were easily separated from the diluted draw solution by applying the magnetic field.

Recyclable magnetic-Pickering emulsion liquid membrane for extracting phenol compounds from wastewater

A Pickering emulsion liquid membrane (PELM) stabilized by oleic acid-coated Fe3O4 nanoparticles has been prepared and used to extract phenolic compound from wastewater. Compared to traditional emulsion liquid membrane (ELM), nano-Fe3O4 particle-stabilized PELM can be easily demulsified after extraction under magnetic field, which could greatly improve the reutilization of oil phase and reduce the energy consumption of ELM operation. Practically, our PELM contains tri-n-butyl phosphate as a carrier, corn oil as a liquid membrane, and sodium hydroxide as a stripping agent. The stability of Pickering emulsion was investigated under different homogenization speeds and characterized by centrifugal stability method. Reutilization of emulsifier and oil phase exhibited comparable extraction efficiency after three cycles of remediation, and no significant change on the particle property was observed.

Magnetic boron specific chelating microsphere by dispersion polymerisation for boron adsorption

Magnetic poly(glycidylmethacrylate) microspheres were prepared by dispersion polymerisation in the presence of oleic acid coated Fe3O4 nanoparticles and modified by N-methyl-D-glucamine for the fabrication of magnetic boron specific chelating microspheres. The structure and properties of obtained microspheres were analysed by scanning electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The utility efficiency of monomer reached 60% under an optimum dropwise feeding process. The magnetic microspheres are ∼1 μm in size, and superparamagnetic nanoparticles have a saturation magnetisation of 17.1 emu g− 1 and a Fe3O4 content of 28 wt.%. The resultant boron specific chelating sorbent presents an adsorption capacity of 0.43 mmol g− 1 in the optimum conditions. Fast separation by magnetic field makes the prepared microspheres useful for the purification of boron contaminated water. These microspheres will exhibit strong potential in the treatment of boron contaminated water by rapid cost efficient separation under external magnetic field.

Copper Ferrocyanide-Functionalized Magnetic Adsorbents Using Polyethyleneimine Coated Fe3O4 Nanoparticles for the Removal of Radioactive Cesium.

Copper ferrocyanide-functionalized magnetic nano-adsorbents were successfully synthesized by electrostatic coating of citric acid coated Fe3O4 nanoparticles with polyethyleneimine, and immobilizing copper and ferrocyanide on the surfaces of polyethyleneimine-coated nanoparticles. Radioactive cesium (Cs) adsorption tests were conducted to investigate the effectiveness of the copper ferrocyanide-functionalized magnetic nano-adsorbents toward the removal of radioactive Cs.

Polymer-coated magnetic nanospheres for preconcentration of organochlorine and pyrethroid pesticides prior to their determination by gas chromatography with electron capture detection

Magnetic polymer nanospheres were prepared and used as adsorbents for the extraction of organochlorine and pyrethroid pesticides from water samples. The adsorbents were synthesized by miniemulsion polymerization of N-vinylimidazole and divinylbenzene and simultaneous encapsulation of oleic acid-coated Fe3O4 nanoparticles. Following desorption with ethyl acetate, the target analytes β-hexachlorocyclohexane, δ-hexachlorocyclohexane, p,p’-DDE, heptachlor, trans-chlordan, cis-chlordan, bifenthrin, β-cypermethrin, δ-methrin, λ-cyhalothrin and esfenvalerate were determined by gas chromatography with electron capture detection. Desorption conditions, extraction times and sample volume were screened by Plackett-Burman design and optimized by Box-Behnken design. Under the optimum conditions, the organochlorines can be quantified in the 20 to 400 ng L−1 concentration range, and the pyrethroids in the 400 to 4000 ng L−1 concentration range. The recoveries of organochlorines and pyrethroids from spiked real water samples are between 77.6 and 97.3 %, with relative standard deviations between 0.9 and 10.0 %. The method for magnetic solid phase extraction described here is fast, simple and friendly to the environment.

Silica sulfuric acid-coated Fe3O4 nanoparticles as high reusable nanocatalyst for the oxidation of sulfides into sulfoxides, protection and deprotection of hydroxyl groups using HMDS and Ac2O

Oxidation of sulfides, acetylation of alcohols and phenols and selective trimethylsilylation of primary and secondary benzyl alcohols are carried out using silica sulfuric acid-coated Fe3O4 magnetic nanoparticles (SSA@MNPs) as a stable, efficient and magnetically recoverable nanocatalyst. Also, deprotection of silyl ethers was reported in ethanol at room temperature in the presence of SSA@MNPs as a magnetic nanocatalyst. The magnetic nanocatalyst was characterized by FT-IR spectroscopy, TGA, XRD and SEM techniques. The catalyst was easily separated with the assistance of an external magnetic field from the reaction mixture and reused for several consecutive runs without significant loss of its catalytic efficiency.

Imaging and Chemotherapeutic Comparisons of Iron Oxide Nanoparticles Chemically and Physically Coated with Poly(ethylene glycol)-&lt;I&gt;b&lt;/I&gt;-Poly(&lt;I&gt;ε&lt;/I&gt;-caprolactone)-&lt;I&gt;g&lt;/I&gt;-Poly(acrylic acid)

We designed a new copolymer, poly(ethylene glycol)-block-poly(ε-caprolactone)-graft-poly(acrylic acid) (PAA-PEC), which could be chemically and physically coated onto iron oxide (Fe3O4) nanoparticles for theranostic applications. The chemically PAA-PEC-coated Fe3O4 nanoparticles (PAA-PEC-IO) were prepared using the carboxylic groups of PAA-PEC to bind the Fe3O4 nanoparticles during a co-precipitation reaction. Because of the amphiphilic properties of PAA-PEC, the compound self-assembled into a core-shell structure. The hydrophobic oleic acid-coated Fe3O4 nanoparticles could then be physically encapsulated inside the hydrophobic core of PAA-PEC (PAA-PEC-OA-IO) using an emulsion technique. A similar amount of iron content was controlled in both the PAA-PEC-IO and PAA-PEC-OA-IO (-23%). The particle diameters, morphologies, superparamagnetism, drug loading efficiency, and transversal relaxivity (r2) were studied and compared between the two magnetic nanoparticles. All results displayed the chemically-synthesized PAA-PEC-IO nanoparticles had higher potential than did the physically-synthesized PAA-PEC-OA-IO as an MRI contrast agent and a drug delivery carrier. Rodamine123-linked PAA-PEC-IO (PAA-PEC-IO-Rh123) was used as a molecular probe. Flow cytometric diagrams indicated that cellular internalization of PAA-PEC-IO occurred primarily through clathrin-mediated endocytosis.

Magnetic polar post-cross-linked resin and its adsorption towards salicylic acid from aqueous solution

A novel magnetic polar post-cross-linked resin M-PMD-P-A was prepared, characterized and evaluated for its adsorption towards salicylic acid from aqueous solution. M-PMD-P-A was prepared using suspension polymerization of methyl acrylate (MA) and divinylbenzene (DVB) with addition of oleic acid-coated Fe3O4 nanoparticles, followed by a Friedel–Crafts reaction and an amination reaction. The results indicated that M-PMD-P-A had a large equilibrium capacity towards salicylic acid, and both of the Langmuir and Freundlich models were appropriate for fitting the equilibrium data. The breakthrough capacity at C/C0=0.05 and saturated capacity at C/C0=0.95 of salicylic acid on M-PMD-P-A were measured to be 45.65 and 62.25mg/mL wet resin, respectively. A mixture desorption solvent containing 0.01mol/L of NaOH (w/v) and 20% of ethanol (v/v) could regenerate the resins completely and the resins exhibited good reusability.

Temperature dependent light transmission in ferrofluids

We investigate the influence of temperature on the magnetic field induced light transmission in a kerosene based ferrofluid containing oleic acid coated Fe3O4 nanoparticles, where the direction of propagation of light is parallel to the direction of the external magnetic field. At a fixed temperature the transmitted light intensity is found to monotonically increase with incident wavelength due to reduced extinction efficiency at higher wavelength. The transmitted intensity decreases with external magnetic field due to enhanced scattering from the field induced linear chain like structures along the direction of the external magnetic field and due to the build-up of standing waves inside the scattering medium. The extinction of the field induced transmitted light intensity is found to occur at a lower external field as the sample temperature is lowered. The rate of extinction of normalized transmitted light intensity decreased linearly with increasing sample temperature due to slower field induced aggregation kinetics because of an increased Brownian motion of the suspended nanoparticles and a reduced coupling constant. The observed temperature dependent magneto-optical properties of magnetic nanofluids can be exploited for applications in optical devices.

Phosphatidylcholine-coated iron oxide nanomicelles for in vivo prolonged circulation time with an antibiofouling protein corona.

We report the synthesis of micellar phosphatidylcholine-coated superparamagnetic iron oxide nanoparticles as a new long circulation contrast agents for magnetic resonance imaging. Oleic acid-coated Fe3 O4 nanoparticles were first prepared through thermal degradation and then encapsulated into small clusters with a phosphatidylcholine coating to obtain hydrophilic nanomicelles. A thorough characterization confirmed the chemical nature of the coating and the excellent colloidal stability of these nanomicelles in aqueous media. Magnetization and relaxivity properties proved their suitability as magnetic resonance imaging (MRI) contrast agent and in vitro cell viability data showed low toxicity. Vascular lifetime and elimination kinetics in the liver were assessed by blood relaxometry and by in vivo MRI in rats and compared with "control" particles prepared with a polyethylene glycol derivative. These micellar particles had a lifetime in blood of more than 10 h, much longer than the control nanoparticles (≈2 h), which is remarkable considering that the coating molecule is a small biocompatible zwitterionic phospholipid. The protein corona was characterized after incubation with rat serum at different times by high-throughput proteomics, showing a higher proportion of bound apolipoproteins and other dysopsonins for the phosphatidylcholine particles. The antibiofouling properties of this corona and its resistance to the adsorption of proteins corroborate the observed enhanced stability and prolonged systemic circulation.

Controllable synthesis and characterization of Fe3O4/Au composite nanoparticles

Abstract Fe3O4/Au composite nanoparticles (GoldMag NPs) have received considerable attention because of their advantageous properties arisen from both individual Au and Fe3O4 nanoparticles. Many efforts have been devoted to the synthesis of these composite nanoparticles. Herein, GoldMag NPs were reported to be synthesized by two-step method. Fe3O4 nanoparticles were prepared by co-precipitation and modified by the citric acid, and then citric acid-coated Fe3O4 nanoparticles were used as seeds in sodium citrate solution to reduce the HAuCl4. The size of obtained nanoparticles was geared from 25 to 300 nm by controlling the concentration of reactants. The GoldMag NPs were characterized by UV–vis spectrometer, dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The GoldMag NPs showed good superparamagnetism at room temperature and were well dispersed in water with surface plasmon resonance absorption peak varied from 538 nm to 570 nm.

Preparation and Characterization of Magnetic Microspheres with an Epoxy Group Coating and Their Applications for Lipase Immobilization

Magnetic microspheres coated with epoxy groups (Ep) were prepared by suspension polymerization of glycidyl methacrylate (GMA) and styrene (St) in the presence of oleic acid-coated Fe3O4 (OA-Fe3O4) nanoparticles, using ethylene glycol dimethacrylate (EGDMA) as a cross-link reagent. The resulting magnetic microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). It was verified that the magnetic microspheres had small diameters of 10–30 μm, as well as having super paramagnetism with a saturation magnetization of 10.5 emu/g. Porcine pancreas lipase (PPL) was selected as a model enzyme to be covalently immobilized (IPPL) on the magnetic microspheres via the reactive Ep; they had an activity yield up to 58.6%, when the protein loading reached 55.4 mg/g supports. In addition, the resulting immobilized lipases exhibited a better thermal stability, temperature and pH endurance than that of the free ones. In particular, an excellent reusability of IPPL, which could meet industrial requirements, was achieved.

One pot synthesis of water-dispersible dehydroascorbic acid coated Fe3O4 nanoparticles under atmospheric air: Blood cell compatibility and enhanced magnetic resonance imaging

Water dispersible and biologically important molecule dehydroascorbic acid (DHA, capable to cross the blood brain barrier) coated Fe3O4 superparamagnetic nanoparticles having an average size of ∼6nm were synthesized through one pot aqueous coprecipitation method under atmospheric air. An antioxidant ascorbic acid (AA) used in the synthesis oxidized itself to dehydroascorbic acid (DHA) to consume dissolved or available oxygen in reaction mixture which died away the oxidative impact of atmospheric air and formed DHA encapsulated the Fe3O4 nanoparticles which stabilized the Fe3O4 nanoparticles and significantly enhanced their colloidal solubility in water. Fe3O4 phase, superparamagnetic property, DHA coating and stable colloidal solubility in water were confirmed by means of XPS, VSM, IR and zeta potential analysis respectively. T1, T2 and T2∗ weighted magnetic resonance imaging (MRI) and corresponding relaxivity (r1=0.416, r2=50.28 and r2∗=123.65mM−1 and r2/r1=120.86, r2∗r1=297.23) of colloidally dispersed DHA-coated nanoparticle water phantom revealed a strong contrast enhancement in T2 and T2∗ weighted images. The compatibility of DHA-coated Fe3O4 nanoparticles toward human blood cells was examined by means of cell counting and cell morphological analysis with the use of optical microscope and scanning electron microscope imaging.