Magnetometric study of gadolinium solubility in magnetite nanocrystals

Gadolinium ions have been demonstrated experimentally to be incorporated into magnetite nanoparticles. Increasing the percentage of gadolinium considerably reduces the magnetic moment of the magnetite nanoparticles (by two orders of magnitude). This effect is discussed in terms of known models for the effect of nanocrystal size (the number of dopant atoms) on the dopant solubility in nanocrystals. Experimental data obtained for a system of gadolinium-doped iron oxide nanoparticles by magnetometry are in qualitative agreement with the models.     

Luminescence properties of Mn and Ni doped ZnS nanoparticles synthesized by capping agent

ZnS and transition metal (Mn and Ni) doped ZnS were synthesized by a simple chemical method using alkyl hydroxyl ethyl dimethyl ammonium chloride (HY) as capping agent. The structural and optical properties were studied using various techniques. FTIR and X-ray diffraction (XRD) can be used to identify the chemical bonding and crystal structure. The XRD analysis show that the particles are in cubic structure. The mean size of the nanoparticles calculated through Scherrer equation is in the range of 5–2.5 nm. Elemental dispersive analysis of doped samples reveals the presence of doping ions. The transmission electron microscopic studies show that the synthesized particles are in spherical shape. Optical characterization of both undoped and doped samples was carried out by ultraviolet–visible and photoluminescence spectroscopy. The absorption spectra of all the samples are blue shifted from the bulk ZnS.     

Facile preparation of magnetic sodium alginate/carboxymethyl cellulose composite hydrogel for removal of heavy metal ions from aqueous solution

A novel magnetic polysaccharide composite hydrogel was successfully constructed by using sodium alginate (SA) and carboxymethyl cellulose (CMC) as the backbone and filled with in situ Fe₃O₄ nanoparticles, which was then employed for removal of heavy metal ion from aqueous solution. The obtained magnetic SA/CMC composite hydrogel was characterized by Fourier transform infrared spectroscopy, fluorescence microscope, thermogravimetric and vibrating sample magnetometer. Effect of contact time, pH and adsorbent dosage on the adsorption of heavy metal ions by the magnetic SA/CMC hydrogel have also been studied. The results show that the prepared magnetic SA/CMC hydrogel can be effectively utilized in the removal of heavy metal ions from aqueous solution. The maximal adsorption capacity of Mn(II), Pb(II), and Cu(II) as calculated from the Langmuir model were 71.83, 89.49, and 105.93 mg/g, respectively. The adsorption process of the magnetic SA/CMC hydrogel on the heavy metal ions can be attributed to ion exchange and chemical adsorption. What’s more, the magnetic hydrogel exhibited high efficiency after four cycles, which indicating it offers great potential for practical application in the removal of heavy metal ions from aqueous solution.

     

Preparation of manganese-based perovskite nanoparticles using a reverse microemulsion method: biomedical applications

In this study, La_0.7Sr_0.3Mn_0.98Ti_0.02O₃ (LSMTO) nanoparticles with a perovskite structure and an average particle size of 23.5 nm were synthesized using a reverse microemulsion method. In this method, cetyltrimethylammonium bromide (CTAB) was used as a surfactant, 1-butanol as a co-surfactant, n-hexane as a continuous oil phase, and an aqueous solution containing metal cations or precipitating agent as a dispersed aqueous phase. The aqueous nanodroplets of microemulsions were used for the formation of perovskite precursor. The obtained precursor was then calcined at 700 ^° C for 4 h to convert the precursor to the perovskite phase. In addition, the heating ability of the LSMTO nanoparticles was evaluated under a safe alternating magnetic field used in magnetic hyperthermia therapy. The results showed the fast magneto-temperature response of the prepared sample with sufficient heat loss at the therapeutic temperature range, indicating the LSMTO nanoparticles can be used as a self-regulated heating agent in the magnetic hyperthermia therapy.     

Structure and optical properties of capped and uncapped CdS nanoparticles prepared in aqueous medium

We have prepared the hexagonal structure of CdS nanoparticles in an aqueous solution with different sizes and varied surface compositions by using fixed molar ratio of the starting precursors in the presence of capping molecules. In addition, we have prepared uncapped CdS nanoparticles by cadmium chloride and thiourea at low temperature. We showed that the environmental conditions and the type of the aqueous medium are the effective parameters for the exchange of the nanoparticle size. The prepared nanoparticles have sizes in the range from 25 to 100 Å. We have compared the experimentally determined size of CdS nanoparticles with that determined by theoretical calculations. The comparison showed that the size determined by Scherrer’s equation is fitted well with the empirical tight binding calculations, and that the effective mass approximation yields size values is in good agreement with the size estimated by high resolution transmission electron microscopy. Photoluminescence spectroscopy revealed that the nanoparticles with stoichiometries composition S/Cd ~ 1 have a high intensity band edge emission in the blue region for the capped nanoparticles and green emission for the uncapped nanoparticles.     

Tailoring silver nanoparticle construction using dendrimer templated silica networks

We have examined the role of the internal environment of dendrimer templated silica networks in tailoring the construction of silver nanoparticle assemblies. Silica networks from which 3,5-dihydroxybenzyl alcohol based dendrimer templates have been completely removed, slowly wet with an aqueous solution of silver acetate. The latter then reacts with internal silica silanol groups, leading to chemisorption of silver ions, followed by the growth of silver oxide nanoparticles. Silica network constructed using generation 4 dendrimer contains residual dendrimer template, and mixes with aqueous silver acetate solution easily. Upon chemisorption, silver ions get photolytically reduced to silver metal under a stabilizing dendrimer environment, leading to the formation of silver metal nanoparticles.     

Magnetic and Structural Study of FeNi3 Nanoparticles: Effect of Calcination Temperature

Bimetallic Fe–Ni alloy nanoparticles (NPs) with molar ratio of Fe to Ni 1:3 were synthesized via chemical reduction using hydrazine in aqueous solution and then calcined at different temperatures. The prepared NPs have been characterized utilizing X-ray diffraction (XRD), energy-dispersive X-ray (EDS) spectroscopy, and vibrating sample magnetometer (VSM). XRD results show that FeNi₃ NPs with face-centered cubic (FCC) crystalline structure were formed. FeNi₃ phase completely disappeared and pure NiO and NiFe₂O₄ phases observed on further heating at 550° C. VSM results reveal a superparamagnetic characteristic for the synthesized NPs when calcined at 50° C. An increased coercivity and decreased saturation magnetization has been observed with increasing calcination temperature up to 550° C.     

Comparative study of synthesized silver and gold nanoparticles using leaves extract of <Emphasis Type="Italic">Bauhinia tomentosa</Emphasis> Linn and their anticancer efficacy

Nanotechnology is an emerging field in science and technology, which can be applied to synthesize new materials at the nanoscale level. The present investigation aimed at comparing the synthesis, characterization and in vitro anticancer efficacy of synthesized silver and gold nanoparticles using leaves extract of Bauhinia tomentosa Linn. Silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized using aqueous extract of leaves with solution of silver nitrate (AgNO₃, 1 mM) and chloroauric acid (HAuCl₄?3H₂O, 1 mM), respectively. The synthesized nanoparticles were characterized using UV–visible spectrophotometry, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive analysis of X-rays, X-ray diffraction, thermogravimetric analysis and cyclic voltammetry, which confirmed the reduction of Ag⁺ ions to Ag⁰ and Au³⁺ ions to Au ⁰ . The in vitro anticancer efficacy of AgNPs, AuNPs and aqueous extract of leaves confirmed by MTT assay exhibited IC₅₀ concentrations of 28.125, 46.875 and 50 μg ml^?1 for lung A-549 cells, 103.125, 34.375 and 53.125 μg ml^?1 for HEp-2 cells and 62.5, 23.4 and 13.26 μg ml^?1 for MCF-7 cells, respectively. The concentrations indicate that both silver and gold nanoparticles as well as aqueous extract of leaves exhibited high anticancer efficacy.     

Electrospun green fibres from lignin and chitosan: a novel polycomplexation process for the production of lignin-based fibres

Novel lignin-chitosan polyelectrolyte fibres were produced through a reactive electrospinning process. Polyelectrolyte formation between the anionic lignin and cationic chitosan was controlled through the pH of the solution. Through manipulating the polyelectrolyte complex formation, fibres could be effectively produced from two biopolymers, which are normally very difficult to electrospin on their own. Though minimal amounts of the petroleum-derived polyethylene oxide were introduced into the solution to enhance the spinnability of the polyelectrolyte solution, it could be easily removed from the fibres post spinning by washing with water. Thus, pure biopolymer fibres could be produced. The optimum composition of lignin to chitosan was identified through SEM, FTIR and TGA analysis of the electrospun fibres. Fluorescence spectra of the electrospun fibres reveal the homogeneous distribution of lignin and chitosan components throughout the fibre network.     

N-methacryloyl-(l)-histidine methyl ester carrying porous magnetic beads for metal chelate adsorption of cytochrome c

A magnetic metal-chelate adsorbent utilizing N-methacryloyl-(l)-histidine methyl ester (MAH) as a metal-chelating ligand was prepared. MAH was synthesized using methacryloyl chloride and l-histidine methyl ester. Magnetic beads with an average diameter of 50–100 μm were produced by suspension polymerization of ethylene glycol dimethacrylate (EGDMA) and MAH carried out in a dispersion medium. Specific surface area of the magnetic beads was found to be 80 m²/g. Elemental analysis of the magnetic beads for nitrogen was estimated as 70 μmol MAH/g polymer. Magnetic beads were complexed with the Cu²⁺ ions directly via MAH for the adsorption of cytochrome c from aqueous solutions. The cytochrome c adsorption on the mag-poly(EGDMA–MAH) beads was 51 mg/g. Cu²⁺ complexing increased the cytochrome c adsorption significantly. The maximum cytochrome c adsorption capacity of the Cu²⁺-chelated beads (carrying 68 μmol Cu²⁺ per gram of polymer) was found to be 222 mg/g at pH 8.0 in phosphate buffer. Cytochrome c adsorption decreased with increasing temperature. Cytochrome c molecules could be reversibly adsorbed and desorbed ten times with the magnetic adsorbents without noticeable loss in their cytochrome c adsorption capacity. The resulting magnetic chelator beads posses excellent long term storage stability.     

Prussian-blue-modified iron oxide magnetic nanoparticles as effective peroxidase-like catalysts to degrade methylene blue with H2O2

Prussian-blue (PB)-modified γ-Fe(2)O(3) magnetic nanoparticles (PBMNPs) were successfully synthesized based on electric interactions between negatively charged [Fe(CN)(6)](4-) and positively charged γ-Fe(2)O(3) nanoparticles. The in situ PB coating was generated by the coordinating reaction between the adsorbed [Fe(CN)(6)](4-) and the ferric ions on the surface of γ-Fe(2)O(3) NPs. The as-prepared PBMNPs were characterized by FT-IR, XRD, TEM, and used to remove organic pollutants from aqueous solution, namely, using methylene blue (MB) as model compound. The experimental results showed that the target compound could be removed efficiently from solution over a wide pH range from 3 to 10 in the presence of PBMNPs as peroxidase-like catalyst and H(2)O(2) as oxidant. Under optimal conditions, MB could be removed completely after 120 min of reaction at 298 K; the chemical oxygen demand (COD) removal efficiency and the total organic carbon (TOC) abatement efficiency were 53.6% and 35%, respectively. Furthermore, the PBMNPs catalysts showed high magnetization, temperature tolerance, long-term storage and operational stability, and they could be readily separated from solution by applying an external magnetic field. Finally, a possible reaction mechanism for MB degradation was also discussed.     

The in vitro therapeutic activity of betulinic acid nanocomposite on breast cancer cells (MCF-7) and normal fibroblast cell (3T3)

In the present study, magnetic nanoparticles (MNPs) were coated with chitosan (CS) polymer to form CS–MNP nanoparticles. The CS–MNP were loaded with an anticancer drug, betulinic acid (BA) to form a BA–CS–MNP nanocomposite. The prepared nanocomposite was characterized using XRD, FTIR, TGA, VSM, SEM, TEM, and zeta potential techniques. The release behavior of the BA from the nanocomposite was investigated at pH 7.4, and the study found that the release of BA followed a pseudo-second-order kinetic model. The potential cytotoxicity of free BA, MNPs, CS–MNP, and the BA–CS–MNP nanocomposite was evaluated using normal mouse fibroblast cells (3T3) and breast cancer cells (MCF-7). BA and the nanocomposite at concentrations in the range 0.781–50 μg mL^?1 did not affect the viability of normal cells during 72 h of incubation. The BA and BA–CS–MNP nanocomposite exhibited cytotoxicity in MCF-7 cells in a dose-dependent manner with IC₅₀ values of 2 and 3.6 μg mL^?1, respectively.     

Effect of copper nanoparticle addition on the electrical and optical properties of thin films prepared from silver nanoparticles

The fabrication of transparent and conductive silver (Ag) and copper (Cu)-doped Ag films using simple spin-coating method with Ag and Cu nanoparticles (NPs) as starting material is described in this study. The aggregation of Ag NP and the grain formation caused by heat treatment were hindered by the addition of small amount Cu NP, and a continuous film was obtained even though the thickness was in the order of 10 nm. When the total metal concentration of NP solution precursor was 5 wt% with the ratio between Ag and Cu being 95:5, the surface resistivity (ρ _s) of Ag–Cu film was 3.17 Ω/sq; and when the concentration was reduced to 3.5 wt%, the ρ _s was 16.3 Ω/sq. The transmission of latter was more than 60 % with the maximum value 82.1 % at 328 nm in the near-UV region (300–400 nm), however, decreased to about 38 % in the visible region (400–700 nm) and near-IR region. The inhomogeneity of the film increased leading to the decrease of the conductivity with the time extension during the heat treatment.     

Structural, Optical and Magnetic Properties of Mn-doped CdS Diluted Magnetic Semiconductor Nanoparticles

Diluted magnetic CdS:Mn nanoparticles were synthesized by the aqueous solution method with different manganese (Mn²⁺) concentrations (x=7?C10?atom?%) at room temperature in nitrogen atmosphere and capped with Thiogelycerol. The X-ray diffraction patterns of CdS nanoparticles with different Mn doping concentration indicated that samples have hexagonal structure at room temperature. Energy dispersive X-ray spectroscopy confirmed incorporative of Mn ions in CdS nanoparticles. UV-Visible spectroscopy is used to investigate optical absorption of Mn-doped CdS. From photoluminescence measurement it was found that the intensity of the luminescence spectra decreases by increasing Mn²⁺ dopant ions at high precursor concentration. Also, the room temperature ferromagnetic behavior of Mn-doped CdS nanoparticles is discussed by using hysteresis measurement results.     

Fast removal of copper ions by gum arabic modified magnetic nano-adsorbent

A novel magnetic nano-adsorbent was developed by treating Fe(3)O(4) nanoparticles with gum arabic to remove copper ions from aqueous solutions. Gum arabic was attached to Fe(3)O(4) via the interaction between the carboxylic groups of gum arabic and the surface hydroxyl groups of Fe(3)O(4). The surface modification did not result in the phase change of Fe(3)O(4), while led to the formation of secondary particles with diameter in the range of 13-67nm and the shift of isoelectric point from 6.78 to 3.6. The amount of gum arabic in the final product was about 5.1wt%. Both the naked magnetic nanoparticles (MNP) and gum arabic modified magnetic nanoparticles (GA-MNP) could be used for the adsorption of copper ions via the complexation with the surface hydroxyl groups of Fe(3)O(4) and the complexation with the amine groups of gum arabic, respectively. The adsorption rate was so fast that the equilibrium was achieved within 2min due to the absence of internal diffusion resistance and the adsorption capacities for both MNP and GA-MNP increased with increasing the solution pH. However, the latter was significantly higher than the former. Also, both the adsorption data obeyed the Langmuir isotherm equation. The maximum adsorption capacities were 17.6 and 38.5mg/g for MNP and GA-MNP, respectively, and the Langmuir adsorption constants were 0.013 and 0.012L/mg for MNP and GA-MNP, respectively. Furthermore, both the adsorption processes were endothermic due to the dehydration of hydrated metal ions. The enthalpy changes were 11.5 and 9.1kJ/mol for MNP and GA-MNP, respectively. In addition, the copper ions could desorb from GA-MNP by using acid solution and the GA-MNP exhibited good reusability.     

Synthesis and Characterization of Pure Single Phase BiFeO3 Nanoparticles by the Glyoxylate Precursor Method

Perovskite-type BiFeO ₃ nanoparticles have been synthesized by thermal decomposition of glyoxylate precursor. The effects of different thermal decomposition temperatures (300–600 °C) on the phase evolution, morphology, and physical properties were investigated by thermal analysis, infrared spectroscopy, X-ray diffraction, electron microscopy, vibrating sample magnetometry, and UV–Vis spectroscopy methods. The high purity bismuth ferrite nanoparticles synthesized at 600 °C showed the weak ferromagnetism behavior, due to the size confinement effect. Furthermore, the BiFeO ₃ nanoparticles also exhibited strong absorption in the visible region with the lowest band gap of about 2.08 eV.     

Synthesis and characterization of metal ion-imprinted polymers

In this study, ion-imprinted polymeric materials from an aqueous solution were prepared to remove metal ions \((\hbox {M}^{2+})\) like \(\hbox {Ni}^{2+}\), \(\hbox {Co}^{2+}\), etc. To prepare ion-imprinted polymers (IIPs), acrylic acid derivatives (XA) like acrylamide (AAm), methacrylic acid and itaconic acid were chosen as monomers. Metal ions formed binary chelate complexes with the help of 8-hydroxyquinoline (8-HQ). The solution containing functional monomers and the binary complex were polymerized with the help of various cross-linkers [ethylene glycol dimethylacrylate (EGDMA) or trimethylpropane trimethacrylate (TMPTMA)] and the target ion was removed from this polymer through an applicable method to produce IIPs. Furthermore, the control polymers (CPs) were synthesized through the same method without using metal ion. Characterization of the polymeric materials was investigated through spectroscopic (FTIR/ATR), thermal (TGA, DSC) and surface (SEM and XRD) analyses. Functional monomers, cross-linkers and the target ion’s species were changed during preparation of IIPs to observe their effect on imprinting of the target ion. Adsorption of the target ion to the prepared IIPs and the factors affecting the adsorption like concentration, pH, temperature, mass, etc. were studied.     

Synthesis and characterization of magnetic adsorbent prepared by magnetite nanoparticles and zeolite from coal fly ash

Magnetite nanoparticles were prepared by partial oxidation of Fe(II) ions of an aqueous suspension of hydroxysulfate green rust which was obtained by precipitation of Fe(II) ions. This magnetite was mixed with zeolite synthesized from coal fly ash to obtain the magnetic adsorbent and the final product characterization was made. By analysis of scanning electron microscopy and X-ray diffraction, images of clusters of magnetite nanoparticles were observed and crystallite sizes of 17 nm were determined, respectively. In thermal analysis, the weight ratio of 1:3 for magnetite-zeolite in the magnetic adsorbent was measured and a non-magnetic product at 974 °C was found in both magnetite and magnetic adsorbent. Magnetization measurements described small hysteresis from the clusters of magnetite nanoparticles. Fourier Transform Infrared spectroscopy analysis indicated that the synthesized zeolite is a hydroxy sodalite and evidences of formation of the magnetic adsorbent were observed. The performance of magnetic separation technique was evaluated and it was comparable to the centrifugation process. The magnetic adsorbent indicated a potential application for adsorption of dye Reactive Orange 16 from aqueous solution.     

Preparation of chitosan/magnetite composite beads and their application for removal of Pb(II) and Ni(II) from aqueous solution

A simple and effective process has been proposed to prepare chitosan/magnetite nanocomposite beads with saturation magnetization value as high as uncoated Fe₃O₄ nanoparticles (ca. 54 emu/g). The reason was that the coating chitosan layer was so thin that it did not affect magnetic properties of these composite beads. Especially, chitosan on the surface of the magnetic Fe₃O₄ nanoparticles is available for coordinating with heavy metal ions, making those ions removed with the assistance of external magnets. Maximum adsorption capacities for Pb(II) and Ni(II), occurred at pH 6 and under room temperature were as high as 63.33 and 52.55 mg/g respectively, according to Langmuir isotherm model. These results permitted to conclude that chitosan/magnetite nanocomposite beads could serve as a promising adsorbent not only for Pb(II) and Ni(II) (pH = 4–6) but also for other heavy metal ions in wastewater treatment technology.     

A Chemometric Study of the Adsorption of Zr(IV) Ions from Aqueous Solutions onto TBP-Surface-Modified Magnetic Fe3O4 Nanoparticles as a New Adsorbent

Radiochemistry - Chemometric experimental design methods were used to optimize the adsorption of Zr(IV) ions from an aqueous solution. Tributyl phosphate functionalized magnetic nanoparticles...