Magnetic nanoparticles for application in cancer therapy

Magnetic particles play nowadays an important role in different technological areas with potential applications in fields such as electronics, energy and biomedicine. In this report we will focus on the hyperthermia properties of magnetite nanoparticles and the effect of several chemical/physical parameters on their heating properties. We will discuss about the need of searching new smaller magnetic systems in order to fulfill the required physical properties which allow treating tumoral tissues more efficiently by means of magnetically induced heat. Preliminary results will be shown about the effect of a biocompatible shell of core–shell magnetite NPs on the heating properties by application of a RF magnetic field.     

Synthesis and characterization of Ce doped silica (SiO2) nanoparticles

A series of silica doped with different mol percentages of Ce³⁺ concentration was synthesized using a sol-gel method to determine the dependence of photoluminescence wavelengths and intensity on the concentrations of the dopants. Sol-gel glasses are porous networks that have been densified through chemical processing and heat treatment. Rare-earths (REs) are insoluble in silica; due to this insolubility RE ions in silicate glasses enter as network modifiers and compete for non-bridging oxygen in order to complete their coordination. The morphological, structural, thermal and optical properties of the phosphors were characterized by X-ray diffraction, scanning electron microscopy, UV-vis absorption, photoluminescence, thermogravimetric analyses and differential scanning calorimeter. Silica (SiO₂) gel containing Ce³⁺ ions was sputter coated with Au (gold) in order to monitor surface morphology of the samples. The highest emission intensity was found for the sample with a composition of 0.5 mol% Ce³⁺. Cerium doped silica glasses had broad blue emission corresponding to the ²D_3/2-²F_J transition at 448 nm but exhibited apparent concentration quenching above concentrations of 0.5 mol% Ce³⁺.     

Synthesis and characterization of core-shell europium(III)-silica nanoparticles

Luminescent core-shell europium(III)-silica nanoparticles were prepared using europium(III) chelate core structure and polyvinylpyrrolidone synthesis strategy for silica shell. Europium(III):naphtoyltrifluoroacetone:trioctylphosphineoxide complex was spontaneously agglomerated from organic solvent to water. Polyvinylpyrrolidone was adsorbed onto the core structure and stable silica shell was synthesized using tetraethylorthosilicate. Nanosized particles with a diameter of 71 ± 5 nm and 11 nm shell thickness were obtained with fluorescence decay rate of 517 μs and excitation and emission wavelengths of 334 and 614 nm, respectively.     

Synthesis and characterization of ZnO nanoparticles using polyethylene glycol (PEG)

ZnO nanoparticles and ZnO encapsulated with polyethylene glycol (PEG) was synthesized using zinc acetate as a precursor at low temperature and characterized by different techniques. The influence of the types of solvent, synthesis parameters, and PEG encapsulation on the crystallization, the surface morphology, and the luminescent properties of ZnO nanoparticles prepared by the sol–gel process were investigated. The influence of different addition molar masses of the PEG during the synthesis on the ZnO emission peaks was systematically monitored. The crystallinity, the surface morphology, and the photoluminescence (PL) properties of ZnO depended highly on the synthesis process and PEG encapsulation. X-ray diffraction (XRD) spectra of ZnO nanoparticles show that all the peaks corresponding to the various planes of wurtzite ZnO indicate the formation of a single phase. The absorption edges of these ZnO nanoparticles are shifted by additions of the PEG polymer. The photoluminescence (PL) characterization of the ZnO nanostructures exhibited a broad emission in the visible range with maximum peak at 450 and/or 560 nm.     

Synthesis and characterization of a fatty acid self-assembled monolayer on CeO2 nanoparticles: to explore solution-state property of a SAM

Decanoic acid self-assembled monolayer (SAM) in the quasi-crystalline state was prepared on the surface of the cubic CeO₂ nanoparticles (6.5 ± 1.1 nm) by hydrothermal synthesis. The purification method to obtain quasi-crystalline SAM without residual (free) decanoic acid was developed. The SAM was carefully washed (purified) and characterized carefully by FT-IR, TG, DSC, and NMR. The obtained results showed that good agreement with the property of the dry state SAM. The solution state properties of the SAM were also examined by the CeO₂ nanoparticles. It turned out that the quasi-crystalline SAM could be swollen by its good solvents, cyclohexane, and chloroform; however, the quasi-crystalline SAM showed that a size exclusion effect to the solvent, trans-decalin. In addition, it turned out that the molecular motion of the decanoic acids in the SAM was highly restricted even in the swollen state depending on the distance from the grafting point to the CeO₂ surface. The strong osmosis was also observed. The solvent molecules were not easily released from the SAM even after the solvent molecules outside of the SAM were frozen.     

Synthesis and characterization of indium–tin oxide (ITO) nanoparticles

Synthesis and characterization of ITO nanoparticles were investigated in the present study. To synthesize the ITO nanoparticles flame spray pyrolysis was introduced. The average particle diameter increased with an increase in the molar concentration of the precursor. Raising the maximum flame temperature by controlling the gas flow rates also led to an increase in the average diameter of the particles. The crystalline ITO nanoparticles were synthesized, and their average primary particle diameters ranged from 11 to 20 nm. ITO thin films were prepared with a sol consisted of the ITO nanoparticles and a polymer binder. Effect of average particle diameter of the ITO nanoparticles on the transparency and the surface resistance of the ITO thin films were measured. As the average particle diameter increased, the transparency and the surface resistance decreased from 92 to 83% and from 1.0 × 10⁴ to 0.8 × 10⁴Ω/□, respectively.     

Synthesis and characterization of Rh(PVP) nanoparticles studied by XPS and NEXAFS

Rhodium nanoparticles were synthesized by the reduction of Rh³⁺ ion in ethanol solvent with use of the polyvinylpyrrolidone (PVP) of various molecular weights and the solvent of different volume ratios of water to ethanol. The formed Rh(PVP) nanoparticles have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) techniques. The TEM and AFM results show that the Rh(PVP) nanoparticles are monodispersed and do not agglomerate with each other. The particle size can be controlled by the molecular weight of PVP and/or the water/ethanol ratio of the solvent. The XPS and NEXAFS results indicate that the chlorine derived from RhCl₃(3H₂O) remains in the obtained nanoparticles but can be removed by heating.     

Synthesis and luminescent properties of spindle-like YVO4:Ln3+ (Ln=Eu,Dy) self-assembled of nanoparticles

Large-scale spindle-like YVO₄ particles with an euatorial diameter of 100–150 nm and a length of 300–350 nm were synthesized by utilizing the Y(OH)CO₃ colloid spheres as the precursor and NH₄VO₃ as the vanadium source through a simple solution-based hydrothermal process, for the first time. In the first stage of the reaction, hierarchical flower-like YVO₄ spheres were formed. Then, petals of spindle-like YVO₄ particles were obtained via a following self-abscission process from these flower spheres. The possible formation mechanism has been discussed in detail. Moreover, the photoluminescent properties of spindle-like YVO₄:Ln³⁺ (Ln=Eu, Dy) nanoparticles were investigated. They might have potential application in advanced flat panel display, minioptoelectronic devices, and biological labeling.     

Synthesis, characterization and luminescence properties of novel beta-diketone and Eu(III) ternary complex

The novel beta-diketone 1-(4-bromophenyl)-3-phenylpropane-1, 3-dione (L) was synthesized at room temperature by classical Claisen condensation reaction. With the beta-diketone L as the first ligand and phen as the secondary ligand, and a new rare-earth Eu (III) ternary complex was prepared. The ligand L and ternary complex were characterized by elemental analysis, IR spectra, UV spectra and fluorescence spectra. IR spectra indicated that: the novel ligand L contained the structure of beta-diketone, where the content of enol was high; the Eu3+ ion in the ternary complex was coordinated with six oxygen atoms of three L ligands and two nitrogen atoms of the second ligand phen. UV spectra showed that the main absorption was from the first ligand L in the Eu (III) ternary complex. The excitation and emission spectra of the ternary complex were measured and investigated. Fluorescence spectra demonstrated that the ternary complex could emit characteristic fluorescence of rare earth Eu3+ ion and the strongest emission band was narrow which was attributed to the 5 D0 --> 7 F2 transitions of the 4f electrons of the central Eu3+ ions. So, the new Eu(III) ternary complex is an excellent red-emitter which would be regarded as a valuable material with bright red fluorescence because it presents good monochromaticity.     

Synthesis and characterization of copper oxide (I) nanoparticles produced by pulsed sonoelectrochemistry

Cu(2)O nanopowders have been prepared by ultrasound-assisted electrochemistry with a potentiostatic set-up. Their composition has been determined by X-ray diffraction and energy dispersive X-ray spectroscopy. Transmission electron microscopy and centrifugation analyses indicate that the nanopowders consist of agglomerates of variable nanometric diameter grain. Most of particles have a diameter of 8 nm whatever the electrodeposition potential. The influence of the parameters of electrochemical and ultrasonic pulses on the particle diameter was also studied. The specific surface areas determined by Brunauer-Emmet-Teller (BET) model are very high with a value close to 2000 m(2)g(-1).     

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

A comparative study of amine and silver carboxylate adducts [R₁COOAg-2(R₂NH₂)] (R₁ = 1, 7, 11; R₂ = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, ¹³C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies (¹H and ¹³C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

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Graphical abstract The synthesis of a series (bis)alkylamine silver(I) carboxylate complexes in nonpolar solvents were carried out and fully characterized both in the solid and solution. Carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination. The complexes form layered structures which thermally decompose forming nanoparticles stabilized only by aliphatic carboxylates.

     

Synthesis,characterization and magnetic properties of lightly doped La2−xSrxCuO4 (x = 0.04) nanoparticles

Lightly doped La_2−xSr_xCuO₄ (x = 0.04) nanoparticles with different particle sizes have been successfully prepared by a sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared transmission (IR) spectra and superconducting quantum interference device (SQUID) magnetometer. All samples are single phase and have an orthorhombic unit cell. As the particle size reduces, it is found that the IR band at around 685 cm⁻¹ corresponding to the in-plane Cu–O asymmetrical stretching mode shifts to higher frequency and the magnetization exhibits a large enhancement at low temperature. The magnetic susceptibility of all samples follows a modulated Curie law between ∼20 K and ∼100 K and the Curie constant displays a strong dependence on the particle size. It is suggested that as the particle size decreases surface effects should play an important role in the magnetic properties of the nanoparticles.     

Synthesis,characterization, and cytotoxicity of glutathione-PEG-iron oxide magnetic nanoparticles

Recently, increasing interest is spent on the synthesis of superparamagnetic iron oxide nanoparticles, followed by their characterization and evaluation of cytotoxicity towards tumorigenic cell lines. In this work, magnetite (Fe₃O₄) nanoparticles were synthesized by the polyol method and coated with polyethylene glycol (PEG) and glutathione (GSH), leading to the formation of PEG-Fe₃O₄ and GSH-PEG-Fe₃O₄ nanoparticles. The nanoparticles were characterized by state-of-the-art techniques: dynamic light scattering (DLS), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and superconducting quantum interference device (SQUID) magnetic measurements. PEG-Fe₃O₄ and GSH-PEG-Fe₃O₄ nanoparticles have crystallite sizes of 10 and 5 nm, respectively, indicating compression in crystalline lattice upon addition of GSH on the nanoparticle surface. Both nanoparticles presented superparamagnetic behavior at room temperature, and AFM images revealed the regular spherical shape of the nanomaterials and the absence of particle aggregation. The average hydrodynamic sizes of PEG-Fe₃O₄ and GSH-PEG-Fe₃O₄ nanoparticles were 69 ± 37 and 124 nm ± 75 nm, respectively. The cytotoxicity of both nanoparticles was screened towards human prostatic carcinoma cells (PC-3). The results demonstrated a decrease in PC-3 viability upon treatment with PEG-Fe₃O₄ or GSH-PEG-Fe₃O₄ nanoparticles in a concentration-dependent manner. However, the cytotoxicity was not time-dependent. Due to the superparamagnetic behavior of PEG-Fe₃O₄ or GSH-PEG-Fe₃O₄ nanoparticles, upon the application of an external magnetic field, those nanoparticles can be guided to the target site yielding local toxic effects to tumor cells with minimal side effects to normal tissues, highlighting the promising uses of iron oxide nanoparticles in biomedical applications.     

Synthesis and characterization of silica-gold core-shell (SiO<Subscript>2</Subscript>@Au) nanoparticles

This paper reports a systematic investigation of the growth and attachment of small gold nanoparticles to the functionalized surface of larger silica nanoparticles by three different methods. Nearly monodispersed silica particles and gold nanoparticles were prepared by sol-gel method. The size of the particle could be altered by changing the concentration of reactants, temperature and the time for which they react. The nanocoreshell particles prepared by three different methods were studied using scanning electron microscopy (SEM), UV-vis spectroscopy and Fourier transform infrared spectroscopy. We have found that the third method (c), a combination of the first two methods (a) and (b), has given better results.      

Synthesis and characterization of zinc oxide nanoparticles: application to textiles as UV-absorbers

We report the synthesis and characterization of nanosized zinc oxide particles and their application on cotton and wool fabrics for UV shielding. The nanoparticles were produced in different conditions of temperature (90 or 150 °C) and reacting medium (water or 1,2-ethanediol). A high temperature was necessary to obtain small monodispersed particles. Fourier transformed infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray powder diffractometry (XRD) were used to characterize the nanoparticles composition, their shape, size and crystallinity. The specific surface area of the dry powders was also determined. ZnO nanoparticles were then applied to cotton and wool samples to impart sunscreen activity to the treated textiles. The effectiveness of the treatment was assessed through UV–Vis spectrophotometry and the calculation of the ultraviolet protection factor (UPF). Physical tests (tensile strength and elongation) were performed on the fabrics before and after the treatment with ZnO nanoparticles.     

Synthesis,structural characterization,spectroscopic, thermal,dielectric and Hirshfeld surface analysis of 1-(2-methoxyphenyl)piperazinium chloranilate

The new compound 1-(2-methoxyphenyl)piperazinium chloranilate (MPP.CA) was synthesized and studied by the single crystal X-ray diffraction method. Its structure was confirmed by infrared spectroscopy. The crystal structure consists of ribbons of chloranilate anions and 1-(2-methoxyphenyl)piperazinium cations linked together by NH…O hydrogen bonds. Two protons are transferred from a chloranilic acid molecule to the nitrogen of the piperazine in this structure. Measurements of AC conductivity as a function of frequency at different temperatures indicated the hopping conduction mechanism; in addition, the variation of dielectric constant as a function of T confirmed the transition phase indicated by the differential scanning calorimetry (DSC). The physico-chemical properties, UV-Vis, DSC and dielectric properties are described. Hirshfeld surface analyzes all the intermolecular interactions involved within the structure, which are important to stabilize the structure.     

Synthesis and characterization of boron carbide nanoparticles

Boron carbide nanoparticles were made via a reaction of boron, obtained from thermal decomposition of magnesium diboride, with multiwall carbon nanotubes at 1150 °C for 3 h in vacuum. The size of the nanoparticles is smaller than 100 nm. The bamboo structure of the multiwall carbon nanotubes is the key to the successful synthesis of such nanoparticles. Good crystallinity was demonstrated by scanning electron microscope images and X-ray diffraction patterns. The single-crystal nature of each nanoparticle was evidenced by a high-resolution lattice image obtained using a transmission electron microscope. PACS 61.10.Nz; 61.16.Bg; 81.05.Je; 81.07.Bc; 81.07.Wx     

Synthesis and characterization of Ni-Zn ferrite nanoparticles

Nickel zinc ferrite nanoparticles Ni_xZn_1−xFe₂O₄ (x=0.1, 0.3, 0.5) have been synthesized by a chemical co-precipitation method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, electron paramagnetic resonance, dc magnetization and ac susceptibility measurements. The X-ray diffraction patterns confirm the synthesis of single crystalline Ni_xZn_1−xFe₂O₄ nanoparticles. The lattice parameter decreases with increase in Ni content resulting in a reduction in lattice strain. Similarly crystallite size increases with the concentration of Ni. The magnetic measurements show the superparamagnetic nature of the samples for x=0.1 and 0.3 whereas for x=0.5 the material is ferromagnetic. The saturation magnetization is 23.95 emu/g and increases with increase in Ni content. The superparamagnetic nature of the samples is supported by the EPR and ac susceptibility measurement studies. The blocking temperature increases with Ni concentration. The increase in blocking temperature is explained by the redistribution of the cations on tetrahedral (A) and octahedral (B) sites.     

Synthesis, growth and characterization of novel semiorganic nonlinear optical potassium boro-succinate (KBS) single crystals

Single crystals of novel semiorganic material, potassium boro-succinate (KBS) have been grown from aqueous solution by slow evaporation technique. The lattice parameters for the grown crystals were determined by the single crystal X-ray diffraction analysis. The presence of functional groups was estimated qualitatively by using fourier transform infrared (FTIR) analysis. The optical absorption spectrum shows that the UV cut-off wavelength for the grown crystal is at 240 nm. The thermal stability of the KBS crystal was studied by using TG/DTA analysis. The dielectric constant and loss were studied as a function of frequency. Nonlinear optical properties (NLO) test was performed by using Kurtz powder technique.