Synthesis and characterization of lanthanide-doped sodium holmium fluoride nanoparticles for potential application in photothermal therapy

Upconversion nanoparticles (UC NPs) in combination with plasmonic materials have great potential for cancer photothermal therapy. Recently, sodium holmium fluoride (NaHoF₄) is being investigated for luminescence and magnetic resonance imaging (MRI) contrast agent. Here, we present successful synthesis of excellent quality doped NaHoF₄ NPs for possible UC luminescence application and coated for possible photothermal therapy application. Synthesized NaHoF₄ nanocrystals were doped with Yb/Er and coated with gold, gold/silica, silver and polypyrrole (PPy). XRD, XPS and TEM were used to determine structure and morphology of the NPs. Strong UC photoluminescence (PL) emission spectra were obtained from the NPs when excited by near-infrared (NIR) light at 980 nm. Cell viability and toxicity of the NPs were characterized using pancreatic and ovarian cancer cells with results showing that gold/silica coating produced least toxicity followed by gold coating.     

Covalently linked Au nanoparticles to a viral vector: potential for combined photothermal and gene cancer therapy

Hyperthermia can be produced by near-infrared laser irradiation of gold nanoparticles present in tumors and thus induce tumor cell killing via a bystander effect. To be clinically relevant, however, several problems still need to be resolved. In particular, selective delivery and physical targeting of gold nanoparticles to tumor cells are necessary to improve therapeutic selectivity. Considerable progress has been made with respect to retargeting adenoviral vectors for cancer gene therapy. We therefore hypothesized that covalent coupling of gold nanoparticles to retargeted adenoviral vectors would allow selective delivery of the nanoparticles to tumor cells, thus feasibilizing hyperthermia and gene therapy as a combinatorial therapeutic approach. For this, sulfo-N-hydroxysuccinimide labeled gold nanoparticles were reacted to adenoviral vectors encoding a luciferase reporter gene driven by the cytomegalovirus promoter (AdCMVLuc). We herein demonstrate that covalent coupling could be achieved, while retaining virus infectivity and ability to retarget tumor-associated antigens. These results indicate the possibility of using adenoviral vectors as carriers for gold nanoparticles.     

Facile synthesis of hydrophilic polypyrrole nanoparticles for photothermal cancer therapy

PPY nanoparticles, as one of the important organic photothermal agents has been attracted great attention due to their good biocompatibility, high photothermal efficiency, and low cost. In order to further evaluate the size-dependent photothermal effect, PPY nanoparticles with two different sizes have been prepared with a facile method. The near infrared absorption and photothermal effect of the two size PPY nanoparticles were compared. The PPY nanoparticle with small size shows better photothermal effect at the same condition. The photostability, stability, and cytotoxicity in biologic system have also been investigated. In addition, the PPY nanoparticles with small size can kill the cancer cells effectively under the irradiation of 808 nm laser with a low-power density. These findings may provide better information for the application of the PPY nanoparticles on the photothermal ablation of cancer cells.     

Synthesis and characterization of Fe–B nanoparticles for potential magnetic applications

The crystallization and structure of Fe–B nanoparticles (NPs) of different sizes formed in a single process by gas aggregation from Fe₈₀B₂₀ targets were analyzed by transmission electron microscopy. It is concluded that all NPs are covered by an amorphous Fe–B shell while the crystal structure of the NPs core depends on their size. Large NPs with diameters ≥30 nm are monocrystalline tetragonal Fe₃B, small diameter NPs (≤20 nm) are completely amorphous whereas in middle size NPs, with diameters between 20 and 30 nm, difference Fe–B phases (tetragonal Fe₃B and orthorhombic FeB) together with defaulted areas are observed. This work opens new possibilities to produce Fe–B NPs tailoring their magnetic properties by controlling their size and composition.     

Synthesis and characterization of PEG-iron oxide core-shell composite nanoparticles for thermal therapy

In this study, core-shell nanoparticles were developed to achieve thermal therapy that can ablate cancer cells in a remotely controlled manner. The core-shell nanoparticles were prepared using atomic transfer radical polymerization (ATRP) to coat iron oxide (Fe₃O₄) nanoparticles with a poly(ethylene glycol) (PEG) based polymer shell. The iron oxide core allows for the remote heating of the particles in an alternating magnetic field (AMF). The coating of iron oxide with PEG was verified through Fourier transform infrared spectroscopy and thermal gravimetric analysis. A thermoablation (55 °C) study was performed on A549 lung carcinoma cells exposed to nanoparticles and over a 10 min AMF exposure. The successful thermoablation of A549 demonstrates the potential use of polymer coated particles for thermal therapy.     

Synthesis and characterization of fluoride xerogels

Using coprecipitation from aqueous solutions, we have synthesized transparent fluoride xerogels with both hexagonal (NdF₃, PrF₃, and CeF₃; tysonite structure) and cubic (Sr_0.6Y_0.4F_2.4, Ba₄Y₃F₁₇:Bi, and Ba₄Y₃F₁₇:Yb; fluorite structure) symmetries. As shown by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy, the transparent xerogels have a hierarchical structural organization: primary nanoparticles 20–30 nm in size form agglomerates about 100 nm in size, which in turn form a “skeleton” with many voids and channels up to hundreds of nanometers in size.     

Temperature modulation of concentration quenching in lanthanide-doped nanoparticles for enhanced upconversion luminescence

Nano Research - The doping concentration of lanthanide ions is important for manipulating the luminescence properties of upconversion nanoparticles (UCNPs). However, the serious concentration...     

Synthesis and characterization of copper nanoparticles

Reduction of copper salt by sodium citrate/SFS and myristic acid/SFS leads to phase pure Cu nanoparticles. However, a similar reaction with hydrazine hydrate (HH) and sodium formaldehyde sulfoxylate (SFS) in polymer afforded only a mixture of Cu₂O and Cu. Copper nanoparticles so-prepared were characterized by UV-Visible spectroscopy, X-ray diffraction measurements (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Freshly prepared solutions showed an absorption band at about 600 nm due to surface plasmon resonance (SPR). XRD analysis revealed all relevant Bragg's reflection for fcc crystal structure of copper metal. The particle size by use of Scherrer's equation is calculated to be about 30 nm. TEM showed nearly uniform distribution of the particles in PVA.     

Synthesis and characterization of CdS nanoparticles

In the present work a chemical reduction method is followed to grow CdS nanoparticles at room temperature with varying the amount of reducing agent sodiumborohydride. The dispersed samples in ethanol are characterized using electron diffraction techniques. Simultaneously optical absorption, photoluminescence and longtime photorelaxation of these samples are studied at room temperature. An increase in band gap is observed in each case as compared to bulk CdS. Also particle size decreases with increased amount of reducing agent. Simultaneously long time relaxation increases with decrease of stoichiometric ratio of reducing agent. An attempt is made to correlate the structural, optical, electrical and opto-electrical properties.     

Synthesis and characterization of sodium alkoxides

Alcohol route is being adopted for cleaning sodium from sodium-wetted small components of coolant circuits of fast reactors. For better understanding of sodium-alcohol reactions and their energetics, the data on thermo-chemical properties such as heats of sodium-alcohol reactions, heats of dissolution, heat capacities, thermal decomposition behaviour, etc of their end products are essential. In order to generate such data, high purity sodium alkoxides, viz. sodium methoxide, sodium ethoxide and sodium n-propoxide, were prepared by reacting sodium metal with respective alcohol. These compounds were characterized using X-ray diffraction technique and IR spectroscopy. The elemental analysis was carried out by CHNS analyser and atomic emission spectroscopy. Normal chain sodium alkoxides were found to exhibit tetragonal crystal structure. Crystal structures of sodium ethoxide and sodium n-propoxide are reported for the first time. The IR spectrum of sodium n-propoxide is also reported for the first time.     

Synthesis and magnetic properties of nickel nanoparticles in magnesium fluoride matrix

A new composite material, comprising a diamagnetic matrix (magnesium fluoride) containing metal nanoparticles (nickel), has been synthesized in a high-vacuum laser-based universal cluster ablation system. The structure and magnetic properties of the composite were studied by transmission electron microscopy (TEM) and ferromagnetic resonance (FMR). According to TEM data, the nickel nanoparticles have a spherical shape and their dimensions are described by a narrow distribution function with an average value of 3.2 nm. An analysis of the FMR spectra reveals strong interaction between nickel nanoparticles in the composite, which accounts for an out-of-plane magnetic anisotropy and suggests the formation of granular magnetic films.     

Hydrothermal synthesis,characterization and luminescent properties of lanthanide-doped NaLaF<Subscript>4</Subscript> nanoparticles

Nanoparticles of sodium lanthanum (III) fluoride-doped and co-doped with Eu³⁺/Tb³⁺ were prepared by the hydrothermal method using citric acid as structure-directing agent. Structural aspects and optical properties of synthesized nanoparticles were studied by powder X-ray diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectra (EDS), particle size by dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectrum and photoluminescence (PL) techniques. Nanoparticles consist of well-crystallized hexagonal phase and the average crystallite size for undoped and doped-NaLaF₄ nanoparticles are in the range of 20–22 nm. TEM images show that nanoparticles have cylindrical shape and crystalline nature of nanoparticles was confirmed by SAED patterns. Down- conversion (DC) luminescent properties of doped NaLaF₄ were also investigated and impact of co-doping has been explored.     

Synthesis and characterization of phospholipid-functionalized silver nanoparticles

Functionalizations of silver nanoparticles (AgNPs) by phospholipids (PLs) have been manifested well by means of covalent connection between AgNPs with PLs. After functionalization, the attached PLs can self-assemble into bilayer structures on the surfaces of AgNPs. TEM displays the images of pure AgNPs and functionalized AgNPs with certain thickness of the phospholipid bilayers, as a result of chemical connection existing in AgNPs-PL conjugates. UV-vis and IR spectra confirm the strong Ag-S interaction between silver and sulfur produced during the reactions. This new modification method for AgNPs offers a good opportunity to functionalize nanoparticles with biological activity.     

Synthesis and characterization of titania-coated silver nanoparticles

Silver particles of 70 +/- 10 nm mean diameter were coated with uniform layers of amorphous titania by the hydrolysis and polycondensation process using titanium(IV) n-butoxide in aqueous solution. Because of the large dielectric function of titania, a shift to the longer wavelengths was observed for the plasmon resonance maximum of coated silver nanoparticles. By changing the alkoxide to particles ratio in the reaction mixture, thickness ranging from 5 to 20 nm was obtained. Hydrothermal treatment performed on coated particles at 350 degrees C for 4 h converted amorphous titania to the anatase crystalline form. The anatase form was confirmed by X-ray powder diffraction. More red shift of the plasmon resonance was observed for the hydrothermally treated samples compared with the particles coated with amorphous titania.     

CdS半导体纳米粒子合成与表征

以羟基化SBS为模板,乙酸镉、硫化钠为反应前驱物,利用盐诱导方式在四氢呋喃-甲醇-水体系中制备得到CdS纳米粒子。通过紫外-可见吸收光谱、荧光光谱及透射电子显微镜对CdS纳米粒子的光学性质及形貌进行了表征。结果表明,利用嵌段聚合物的两亲性质,可以得到稳定的具有明显量子尺寸效应的CdS半导体纳米粒子,透射电子显微镜结果表明所得到的CdS半导体纳米粒子具有冠状复合胶束结构。     

Synthesis and characterization of crystalline FeCo nanoparticles

The monodispersed FeCo nanoparticles were synthesized with borohydride as a reducing agent by coprecipitation method in aqueous solution. The composition and the size of FeCo nanoparticle was controlled by fitting the molar ratio of starting material, the reaction time and the falling rate. To prepare the crystallized nanoparticles, the amorphous FeCo nanoparticles were annealed at the different temperatures for 1 hr, respectively. The size of the crystalline FeCo nanoparticles was controlled in order to maintain the uniform size of 20 nm. The as-annealed FeCo alloy could get the highest Ms value of the powder which has been ever synthesized by coprecipitation or other chemical method. The size- and shape-controlled crystalline FeCo nanoparticles can be applied for spring magnet in order to get exchange coupling effect.     

Synthesis and characterization of lithium aluminate nanoparticles

In this work, we report the synthesis of lithium aluminate nanoparticles using simple coprecipitation method in various aqueous surfactant solutions and microemulsion systems. The particles have also been synthesized by coprecipitation without surfactants and sol–gel methods for comparison purpose. Nanocrystalline powders of lithium aluminate with spherical shape were obtained upon calcination. The resultant powders were characterized by XRD, SEM, TGA and BET techniques. As per the results from X-ray diffraction (XRD), the powder prepared by coprecipitation in the presence of Tween 80 and sol–gel showed purer γ-phase when it was calcined at 950 °C. Scanning electron microscopy (SEM) results show that the type of surfactant used has a distinct effect on the size of the lithium aluminate particles. The sample prepared by microemulsion technique shows smaller average particle size of 30 nm and high surface area (70 m²/g).