Greensynthesis of Nanoparticles
Green Synthesis Of Copper Nanoparticles
Application of Magnetic Nanoparticles in Water Purification
The effect of particle size on the adsorption of dissolved heavy metals to iron oxide and titanium dioxide nanoparticles is a matter laboratory-scale experiments.
The crystalline phases were studied by X-raydiffractometry (XRD) operating at a scanning rate of 10°/min from10° to 85° (D/max2550VB3; Rigaku International Corporation, Tokyo,Japan). Identification of the synthesized iron-oxide was based onthe position of characteristic peaks in the diffractograms usingthe Joint Committee on Powder Diffraction Standards (JCPDS)database. The XRD patterns were evaluated to determine the latticespacing (d values) with the Bragg equation and theMiller (hkl) indices corresponding to the crystalline phases in thesamples. The particle size and morphology of the naked and modifiedparticles were examined with a transmission electron microscope(TEM; FTIR, HYPERION2000, Bruker, Ettlingen, Germany). The Fouriertransform infrared (FTIR) spectrum (500–4,000 cm) fromthe KBr pellet containing the PEI-coated magnetic nanoparticles wasrecorded on a FTIR spectrometer. The samples were also examined byX-ray photoelectron spectroscopy (XPS; Kratos, Tokyo, Japan). Themagnetic properties were measured with a vibrating samplemagnetometer (VSM; Lakeshore Cryotronics, Westerville, OH, USA) atroom temperature in magnetic fields of up to 20 kOe.
Size-controlled synthesis of SnO2 nanoparticles by sol-gel method.
A ZnS nanoparticle doped with Mn2+ is synthesized in aqueous media and PVA using chemical co-precipitation method. This colloid was analyzed using uv-vis spectrophotometry. It is observed that the absorption peak blue shifts as compared to the bulk absorption of ZnS suggesting the nanoparticle formation. The energy gaps of these nanoparticles were calculated from the uv-vis spectra. The average particle size analysis is carried out using XRD. Photoluminescence of PVA/ ZnS:Mn2+ is studied. It is observed that the composite sample exhibits an orange emission peak as is reported for pure ZnS: Mn2+.
The PEI-coated nanoparticles were uniformlydispersed in aqueous solution in the absence of a magnetic field. Asuspension of PEI-coated FeO magneticnanoparticles is deep brown. When a magnet was placed under theglass vial, the particles accumulated on the bottom of the vialnear the magnet within a few minutes. After removal of the externalmagnetic field, the aggregates were rapidly redispersed by gentlestirring. The magnetization hysteresis loops of PEI-coated andnaked FeO nanoparticles were measured byVSM at room temperature ().The magnetic data are described by the Langevin equation (), which indicates that the magneticnanoparticles are single-domain, while the samples exhibitsuperparamagnetic behavior at room temperature, as expected by thenanoscale dimension of the particles [the critical size forsuperparamagnetic behavior of magnetite is ~20 nm ()]. The saturation magnetization valuesfor naked and PEI-coated magnetic nanoparticles are lower than thereported saturation magnetization of their bulk counterparts(magnetite, 92–100 emu/g at 300 K). This result is consistent withthat observed for magnetic iron oxide nanoparticles coated withpoly(methacrylicacid) (). Thisphenomenon has been attributed to the presence of nonmagnetic or‘dead’ surface layers resulting from the chemical reaction betweenthe stabilizing surfactant and the ferrite particles (). Such dead surface layers make themagnetic diameter of the particles smaller than its physicaldiameter. Nanoparticles coated with PEI showed an even lower valueof saturation magnetization (Ms, 53.4 emu/g). Davies et al() suggested that particlescontaining sufficient concentrations of functional groups allowspin pinning of the iron oxide surfaces, which gives rise to anon-collinear spin structure and is known to produce reducedmagnetic moments for the particles (,).
Facile synthesis of highly ethanol-sensitive SnO2 nanoparticles.
FANG Li-Mei;LI Zhi-Jie;LIU Chun-Ming;ZU Xiao-Tao. Synthesis of Fe3+-modified SnO2 Nanoparticles by Hydrothermal Method. , 2006, 22(10): 1212-1216.
The surface specificity of XPS renders it a usefulanalytical technique for the direct characterization of iron oxidenanoparticles (,). The observed position of themagnetites is consistent with reported iron assignments (,).The appearance of a satellite peak of Fe 2p3/2 in the XPS spectrais an important feature for discrimination of magnetite frommaghemite (,). As seen in , the absence of the satellite peakfurther substantiates the formation of magnetite in ourexperiments. In addition, the difference in the binding energies ofthe main peaks dE, was 13.4 eV, that is, very similar to thatreported for FeO (13.5 eV) (). It is notable that the XPS analysisof N1s detected one peak at 399.8 eV. This has been commonlyinterpreted as the formation of nitrogen-coordinated metalcomplexes (,). Therefore, the peak position of N1sat 399.8 eV indicates that the nitrogen from the amino groups ofPEI coordinates with the magnetic nanocrystals.
Sonochemical Synthesis and Properties of Nanoparticles …
Sonochemical Synthesis and Properties of Nanoparticles of FeSbO 4
Size-controlled synthesis of SnO2 nanoparticles using reverse microemulsion method.
Synthesis of tin and tin oxide nanoparticles of low size ..
Synthesis and characterization of SnO2 nanoparticles by thermal decomposition of new inorganic precursor.
Synthesis of SnO2 Nanoparticles by High Potential Electrolysis ..
Synthesis of SnO2 nanoparticles through the controlled precipitation route.
Sol gel synthesis of nanoparticles - SlideShare
Transmission electron microscope (TEM)photographs of (A) naked and (B) polyethylenimine (PEI)-coated ironoxide (magnetic) nanoparticles. Selected area electronicdiffraction patterns are shown in the enclosed boxes.
Sol gel synthesis of nanoparticles ..
We report the synthesis of novel diphenylalanine/cobalt(II,III) oxide (Co3O4) composite nanowires by peptide self-assembly. Peptide nanowires were prepared by treating amorphous diphenylalanine film with aniline vapor at an elevated temperature. They were hybridized with Co3O4 nanocrystals through the reduction of cobalt ions in an aqueous solution using sodium borohydride (NaBH4) without any complex processes such as heat treatment. The formation of peptide/Co3O4 composite nanowires was characterized using multiple tools, such as electron microscopies and elemental analysis, and their potential application as a negative electrode for Li-ion batteries was explored by constructing Swagelok-type cells with hybrid nanowires as a working electrode and examining their charge/discharge behavior. The present study provides a useful approach for the synthesis of functional metal oxide nanomaterials by demonstrating the feasibility of peptide/Co3O4 hybrid nanowires as an energy storage material.
Green synthesis of SnO2 nanoparticles and its ..
The magnetism of MNPs commonly comes from magneticmetallic elements or compounds, which are nevertheless easy toaggregate. In addition, since the metallic elements or oxides arereactive in a biological context, they are easily etched inpractice. Therefore, inorganic or organic protective coatings,including silica, polyelectrolyte, lipid layers and micelles, havebeen developed for these particles (). Among these, polymer wrapping, thatis, encapsulation of already fabricated magnetic nanoparticles intopolymer micro- or nanoparticles, is widely used. The magnetic coresensure a strong magnetic response and the polymeric shell providesfavorable functional groups and features that are suitable forvarious applications. These particles are stable in aqueoussuspensions and can be easily redispersed after agglomeration inthe presence of a magnetic field. In addition, the structure,stability and physical properties of nanoscale-size materials canexhibit a strong dependence on the particle surface. Numerouspolymers are biocompatible and may be used as MNP coating forbiomedical applications. Polyethylenimine (PEI) is a branchedpolymer with a high-density amine group,(CHCHNH). The ratio of primaryto secondary to tertiary amines is 1:2:1. In each PEI molecule, onenitrogen atom is protonated per two carbon atoms. Due to thedifferent pKa values of the primary, secondary and tertiary aminogroups, PEI has the ability to capture protons at different pHconditions, which is known as the ‘proton sponge’ mechanism. PEIwas developed to condense DNA via the electrostatic interactionbetween its positive and negative charge of the phosphate group ofDNA (). A PEI-modified MALDIplate was successfully used to concentrate DNA and proteindigestion products (). Due to itsunique properties, PEI appears to be one of the most appropriatemolecules for the surface modification of MNPs for biomedicalapplications.
Sonochemical deposition of silver nanoparticles on silica spheres.
In summary, we synthesized the superparamagneticFeO magnetic nanoparticles coated with PEIby a simple precipitation method. The average grain size ofPEI-coated FeO magnetic nanoparticles is~12.7 nm while that of naked nanoparticles is ~10 nm. The PEI layerwas successfully coated on the surface ofFeO magnetic nanoparticles according to XPSand FTIR analyses. Magnetic measurement showed that thenanoparticles are superparamagnetic. The synthesized PEI-coatedFeO magnetic nanocomposites were used forseparation and enrichment of lung cancer cells. Exfoliativecytopathology analysis showed that the percentage of positive cellsincreased from 6.3% (38/600) in untreated sputum samples to 38.5%(231/600) in sputum samples treated with PEI-coatedFeO magnetic nanocomposites. This findingindicates that PEI-coated FeO magneticnanocomposites can be used to efficiently enrich for lung cancercells from sputum for cytopathology analysis.
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