In‐situ dispersion of ZrO2 nano‐particles coated with pentacene

Stable suspensions of pentacene functionalised ZrO₂ nano‐particles were synthesised using a microwave plasma process. The particles were dispersed in‐situ in ethylene glycol. The formation of coated particles with small cores and a well defined size in the range of 3–5 nm was shown by X‐ray diffraction. In difference to resublimed pure pentacene, suspensions of the coated nano‐particles remained stable for weeks, as confirmed by the observation of a small aggregate size in dynamic light scattering. Thin films of the particles on Si based substrates were obtained by drop‐casting. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The microstructure and specific properties of La/HAP composite powder and its coating

La/HAP composite powder, a novel bioactive material, was prepared using co-precipitation method. The La/HAP coating was obtained for the first time through the dip-coating method, starting from the sols of La/HAP and TiO₂ particles. The compositions and coating of as-produced La/HAP composite powder sintered at temperatures from 300 to 750 °C were analyzed by means of X-ray diffraction (XRD). The changes of the ion groups in as-prepared La/HAP composite powder were characterized by using Fourier transform infrared (FTIR) spectroscopy. Their surface morphologies were observed by means of scanning electron microscope (SEM). The results show that the La/HAP composite powder has higher thermostability than pure HAP powder and La can refine HAP particle and restrain the decomposition of HAP. Consequently, in coating process the heat-treatment temperature is lower (750 °C) using the synthesized La/HAP powder than that using pure HAP (900 °C). The La/HAP coating mainly contains HAP, TiP or Ti₃P₅ and TiO₂ phases as well as a little CaTiO₃ crystal, a very ideal composition to enhance bioactivity of biomaterials. These unique properties of the La/HAP composite powder are beneficial to enhance the strength and bioactivity of coating when it is used as a starting material in coating process.     

Synthesis of Hexagonal ZnO-PQ7 Nano Disks Conjugated with Folic Acid to Image MCF – 7 Cancer Cells

Surface modified ZnO nanomaterial is widely used in the field of bioimaging worldwide due to its optical properties, electronic characteristics and biocompatibility. Fluorescent enhanced, Polyquaternium-7(PQ7) capped, ZnO hexagonal nano disks (ZnO-PQ7) were synthesised by simple wet chemical method. The structural and optical properties of ZnO-PQ7 hexagonal nano disks were characterized using XRD, UV-Visible, Fluorescence, HRTEM, EDAX and FTIR studies. The size of synthesised ZnO-PQ7 were around 30-45 nm as confirmed by HRTEM studies. Fluorescence emission intensity increased with increase in PQ7 concentration. ZnO-PQ7 was further conjugated with folic acid (FA) to target human breast cancer cell line (MCF-7) via EDC/NHS coupling chemistry. Conjugation of folic acid with ZnO-PQ7 was confirmed by FTIR studies. The cell viability study using Methyl thiazolyltetrazolium(MTT) assay has demonstrated that the ZnO-PQ7 conjugated FA composites (ZnO-PQ7-FA) exhibit low toxicity towards MCF-7 up to a concentration of 125 μg/mL. Confocal laser scanning microscopic images confirmed the uptake of ZnO-PQ7-FA nanoparticles by MCF-7 cells. This study reveals ZnO-PQ7-FA nano disks as a potential imaging agent for detection of cancer cells. The synthesis route reported in this article is simple and easy to follow for the synthesis of ZnO-PQ7-FA in bulk quantities with high purity.     

Sonochemical preparation of hydroxyapatite nanoparticles stabilized by glycosaminoglycans

Stable hydroxyapatite (HAP) nanoparticles system was synthesized from Ca(H(2)PO(4))(2) aqueous solution and saturated Ca(OH)(2) aqueous solution by an improved precipitation method. This method was reformed through using ultrasound irradiation as assistant technology due to its unique chemical reaction effects and adding glycosaminoglycans (GAGs) as regulation additive due to its strong interaction with HAP. The products were characterized by Malvern Zetasizer 3000HS Analysis system, TEM and ED. The size distribution and zeta potential of HAP nanoparticles were influenced by the concentration of GAGs. With the GAGs concentration of 0.35g/L, the better excellent HAP nanoparticle system could be obtained with the number-averaged particle size of 22.2nm in 84.5% area and 54.6nm in 15.5% area between 18.1nm and 117.4nm and the zeta potential of -60.9mV. In the presence of GAGs, the particle size and size distribution are little sensitive to the ultrasound irradiation (UI) time. With the increasing of UI time from 0.5h to 3h and 5h, the particle size increased a little and the crystallinity was improved. GAGs inhibited HAP crystal growth and stabilized HAP nanoparticles. Based on the TEM observation and size distribution determination of HAP nanoparticles, the possible formation mechanism of HAP nanoparticles stabilized by GAGs under UI was discussed.     

A convenient synthesis of bis(indolyl)alkanes under ultra sonic irradiation using silica-supported Preyssler nano particles

Bis(indolyl)alkanes have been synthesised in excellent yields in the presence of catalytic amount of silica-supported Preyssler nano particles as green, reusable and efficient catalyst under ultra sonic irradiation.     

Effects of organic modifiers on the size-controlled synthesis of hydroxyapatite nanorods

Size-controlled synthesis of hydroxyapatite nanorods were carried out by chemical precipitation method using polyethylene glycol (MW 600), Tween 20, trisodium citrate, and d-sorbitol as organic modifiers and starting from calcium nitrate, phosphoric acid, and ammonia solution. The influence of the organic modifiers on the sizes of the resultant HAP nanorods was investigated under different synthesis temperatures. It was found that polyethylene glycol was beneficial to the formation of HAP nanorods with a larger aspect ratio (average length/average diameter) at high synthesis temperature, Tween 20 and trisodium citrate favored the formation of small-sized HAP nanorods, and d-sorbitol helped the formation of HAP nanorods with long length at low synthesis temperatures.     

Effect of pre-annealing on NO32- centers in synthetic hydroxyapatite

Effect of pre-annealing of synthetic hydroxyapatite (HAP) on properties of γ- and UV- induced NO₃^2- centers was studied by electron paramagnetic resonance (EPR). Nitrate-containing hydroxyapatite powders ((N)HAP)) and the powders with an admixture of carbonate and nitrate ions ((C,N)HAP) were annealed in the temperature range T_ann = 20 °C ? 600 °C before irradiation. It was found that pre-annealing of (N)HAP samples changes the parameters of NO₃^2- centers while no changes took place in (C,N)HAP. Moreover, at the pre-annealing temperatures T_ann > 200 °C two new NO₃^2- centers were observed in (N)HAP samples; they are characterized by larger value of A_⊥ (3.67 and 4.41 mT) as compared to the known centers. It was also found that the dependence of NO₃^2- centers amount on T_ann is non-monotonous in both types of samples. Presumably this is caused by the escape of water molecules from HAP during the annealing and essential modification of the defect subsystem of HAP.     

Surface modification of hydroxyapatite with poly(methyl methacrylate) via surface-initiated ATRP

This article describes the fabrication of hydroxyapatite (HAP) nanocomposites grafted with poly(methyl methacrylate) (PMMA). Surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was carried out from hydroxyapatite particles derivatized with ATRP initiators. The structure and properties of the nanocomposites were investigated by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), differential scanning calorimeter (DSC) measurements, and contact angle analyses. TGA was used to estimate the grafting density of ATRP initiators (0.49 initiator/nm²) and the amount of grafted PMMA on the HAP surface. The contact angle analyses indicated that grafting PMMA onto the HAP surface dramatically increased the hydrophobicity of the surface. Moreover, the HAP nanocomposites showed excellent dispersibility in both aqueous solution and organic solvent.     

Effects of hydroxyapatite nanoparticles on proliferation and apoptosis of human breast cancer cells (MCF-7)

The study aimed to correlate cell proliferation inhibition with oxidative stress and p53 protein expression in cancerous cells. Hydroxyapatite (HAP) (Ca₁₀(PO₄)₆(OH)₂) is the essential component of inorganic composition in human bone. It has been found to have obvious inhibitory function on growth of many kinds of tumor cells and its nanoparticle has stronger anti-cancerous effect than macromolecule microparticles. Human breast cancer cells (MCF-7) were cultured and treated with HAP nanoparticles at various concentrations. Cells viability was detected with MTT colorimetric assay. The morphology of the cancerous cells was performed by transmission electron microscopy and the expression of a cell apoptosis related gene (p53) was determined by ELISA assay and flow cytometry (FCM). The intracellular reactive oxygen species (ROS) level in HAP exposed cells was measured by H₂DCFDA staining. DNA damage was measured by single-cell gel electrophoresis assay. The statistical analysis was done by one way ANOVA. The cellular proliferation inhibition rate was significantly (p < 0.05) increasing in a dose-dependent manner of HAP nanoparticles. Cell apoptotic characters were observed after MCF-7 cells were treated by HAP nanoparticles for 48 h. Moreover, ELISA assay and FCM shows a dose-dependent activation of p53 in MCF-7 cells treated with nanoHAP. These causative factors of the above results may be justified by an overproduction of ROS. In this study, a significant (p < 0.05) increase in the level of intracellular ROS in HAP-treated cells was observed. This study shows that HAP inhibits the growth of human breast cancer MCF-7 cells as well as induces cell apoptosis. This study shows that HAP NPs Induce the production of intracellular reactive oxygen species and activate p53, which may be responsible for DNA damage and cell apoptosis.     

乙醇热液合成羟基磷灰石粉末的X射线衍射和拉曼光谱分析

为探索热液条件下羟基磷灰石的结晶特点,以氢氧化钙和磷酸中和反应所获沉淀为前驱物,以乙醇为介质在85、100、140℃进行了醇热反应实验。利用X射线衍射(XRD)和拉曼光谱(Raman)对实验样品进行了表征。结果表明,醇热反应能获得结晶良好的羟基磷灰石纳米晶,升高反应温度和延长反应时间有利于羟基磷灰石HAP晶相的生成和晶粒度长大,其中反应温度对产物的晶体结构影响明显。不同反应条件获得的样品的拉曼光谱差异较大,随着反应温度的提高,拉曼光谱先出现PO4四面体的对称伸缩振动,再出现PO4四面体的反对称伸缩振动,最后出现PO4四面体变角振动。     

Direct nano‐scale patterning of Ag films using hard X‐ray induced oxidation

The morphological change of silver nano‐particles (AgNPs) exposed to an intense synchrotron X‐ray beam was investigated for the purpose of direct nano‐scale patterning of metal thin films. AgNPs irradiated by hard X‐rays in oxygen ambient were oxidized and migrated out of the illuminated region. The observed X‐ray induced oxidation was utilized to fabricate nano‐scale metal line patterns using sectioned WSi₂/Si multilayers as masks. Lines with a width as small as 21 nm were successfully fabricated on Ag films on silicon nitride. Au/Ag nano‐lines were also fabricated using the proposed method.     

Effect of the temperature on the synthesis of (K,Na)NbO<Subscript>3</Subscript>-modified nanoparticles by a solid state reaction route

(Na_0.5K_0.5)NbO₃ (KNN)-modified nano-particulated powders, based on variations of sodium–potassium niobate, were synthesised by solid state reaction from carbonate starting materials. The nanoparticles were attained by an optimization of the raw materials particle size and particle refinement of the carbonates during their decomposition. Particle sizes between 50 and 200 nm have been obtained as a function of calcination (decomposition) temperature. The obtained powders showed a co-existence between a tetragonal phase and an orthorhombic phase. The optimization of the raw materials particle size and the particle refinement of the carbonates during their decomposition play a key role in the formation of the KNN-modified nano particles. The developed method is well suited for the production of KNN-modified nano powders at low cost for mass production.     

Improved mechanical properties of hydroxyapatite/poly(?-caprolactone) scaffolds by surface modification of hydroxyapatite

Scaffolds comprising hydroxyapatite (HAP) or poly(?-caprolactone)-grafted hydroxyapatite (g-HAP) and poly(?-caprolactone) (PCL) were prepared using the thermally induced phase separation/salt leaching technique. The g-HAP nanoparticles were evaluated by Fourier Transformation Infrared Spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Power X-ray Diffraction (XRD) patterns confirmed the successful grafting on the surface of HAP. The effects on mechanical strength, porosity and thermal property of scaffolds by the introduction of nanoparticles were extensively investigated. The compressive modulus of the scaffold was greatly improved by the addition of g-HAP nanoparticles. Especially the compressive modulus of the g-HAP/PCL scaffold containing 20 wt% of g-HAP was 59.4% higher than that of the corresponding HAP/PCL scaffold.     

Characterization and evaluation of cytotoxicity of biphasic calcium phosphate synthesized by a solid state reaction route

Calcium phosphate compounds have been widely studied for biomedical applications because of their chemical and structural similarity to the mineral phase constituting bone and teeth. In this work, biphasic calcium phosphate ceramics (HAP/β-TCP), with tunable phase composition ratio, were synthesized by a solid state reaction process. The effect of varying the heat treatment temperature (700, 800, 900, 1000, and 1100 °C) on the formation of the ceramic materials and their related cytotoxicity were examined. The phase composition and morphology of the prepared ceramic powders were characterized by X-ray diffraction and scanning electron microscopy, and the functional groups were analyzed using Fourier transform infrared spectroscopy and Raman spectroscopy. Cell culture experiments, using murine macrophages, showed that the synthesized HAP/β-TCP materials did not exhibit cytotoxicity regardless of the doses assayed or the differences in composition ratio of HAP/β-TCP, suggesting the potential of HAP/β-TCP for biological applications.     

Hydroxyapatite coating on porous silicon substrate obtained by precipitation process

Hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ (HAP) is known as a bioactive and biocompatible material, HAP coatings were used to improve the biocompatible of substrate by many researcher, In this work, HAP thin films on porous silicon (PS) substrates have been prepared by aqueous precipitation method with rapid thermal annealing (RTA) processes. The HAP films had been prepared under the annealing temperature ranging from 300 to 1000 °C. By the measurement of X-ray diffraction (XRD), it was found that for the crystallinity optimization, the heat-treatment at 850–950 °C for 1 h would be favorable. Atomic force microscopy (AFM) and scanning electron microscope (SEM) measurements reveal a dense and smooth surface of the HAP film, and tightly adherence of the coating on porous silicon substrate after sintered. Thus, by this method, porous silicon could be increased its bioactivity and so that could be used in the biomedical area.     

一维棒状纳米纤维素及光谱性质

采用稀酸预处理纤维素浆粕,结合高压均质的物理方法,制备出一维棒状纳米纤维素.通过傅里叶红外光谱(FTIR),X射线衍射(XRD),热重分析(TGA),原子力显微镜(AFM)和透射电镜(TEM)等方法对纳米纤维素光谱性能和形貌结构进行了表征.结果表明,制得的纳米纤维素与纤维素浆粕具有相同的红外特征官能闭,但分子内氢键缔合作用被部分破坏.纳米纤维素与纤维素浆粕同属于纤维素I的晶形类型,结品度从59%提高至70%,仍保持结晶区与无定形区共存的状态.纳米纤维素的分解温度为330℃,热稳定性低于纤维素浆粕,失重温度从292℃持续至500℃,有两个明显失重阶段.纳米纤维素长度为数百纳米,宽度为数十纳米的棒状形态,易产生团聚现象.     

Development of a numerical model for the ballistic penetration of Fackler gelatine by small calibre projectiles

Among the different material surrogates used to study the effect of small calibre projectiles on the human body, ballistic gelatine is one of the most commonly used because of its specific material properties. For many applications, numerical simulations of this material could give an important added value to understand the different phenomena observed during ballistic testing. However, the material response of gelatine is highly non-linear and complex. Recent developments in this field are available in the literature. Experimental and numerical data on the impact of rigid steel spheres in gelatine available in the literature were considered as a basis for the selection of the best model for further work. For this a comparison of two models for Fackler gelatine has been made. The selected model is afterwards exploited for a real threat consisting of two types of ammunitions: 9?mm and .44 Magnum calibre projectiles. A high-speed camera and a pressure sensor were used in order to measure the velocity decay of the projectiles and the pressure at a given location in the gelatine during penetration of the projectile. The observed instability of the 9?mm bullets was also studied. Four numerical models were developed and solved with LS-DYNA and compared with the experimental data. Good agreement was obtained between the models and the experiments validating the selected gelatine model for future use.     

Preparation of uniform porous hydroxyapatite biomaterials by a new method

In this paper, a new method of preparation of uniform porous hydroxyapatite biomaterials was reported. In order to obtain uniform porous biomaterials, disk samples were formed by the mixture of hydroxyapatite (HAP) powders and monodispersed polystyrene microspheres, and then HAP uniform porous materials with different diameter and different porosity (diameter: 436 ± 25 nm, 892 ± 20 nm and 1890 ± 20 nm, porosity: 46.5%, 41.3% and 34.7%, respectively) were prepared by sintering these disk samples at 1250 °C for 5 h. The pure phase of HAP powders fabricated by the hydrothermal technology was confirmed by X-ray diffraction (XRD). The surface and size distribution of pores in HAP biomaterials were observed by scanning electron microscopy (SEM), and the pore size distribution in porous HAP biomaterials was tested by mercury intrusion method.     

EPR study of radiation-induced defects in carbonate-containing hydroxyapatite annealed at high temperature

Radiation-induced (γ or UV) paramagnetic defects in carbonate-containing hydroxyapatite (HAP) annealed at high (600–950 °C) temperature were studied by EPR. The complex spectra reveal the presence of different paramagnetic species. Their contributions were found to be strongly dependent on the annealing temperature as well as microwave power, thus, by the adjustment of experimental conditions some of the components can be eliminated that allowed to record EPR spectra caused by no more than two types of paramagnetic defects. All experimental spectra were analyzed using computer simulation. The parameters of the paramagnetic defects detected were determined, and the centers models were discussed. It was found that high-temperature annealing influences essentially the formation of radiation-induced defects in HAP. The СО₃³⁻, О⁻ centers and oxygen vacancy V_O⁻ were shown to be the main stable γ-induced defects in the HAP annealed at high temperatures. New paramagnetic defect with the parameters g_|| = 2.002, g_⊥ = 2.0135 was detected and tentatively identified as an O-related radical. The γ-induced EPR response from СО₃³⁻ radicals was found to be more intense than response from CO₂⁻ in non-annealed HAP. UV-irradiation was found to create smaller amounts of paramagnetic defects in comparison with γ-rays. Besides, oxygen vacancy V_O⁻ was not observed, while two other centers (СО₃⁻ and the center of unknown nature) appear in the UV-induced EPR spectra.     

Apparatus for rapid adjustment of the degree of alignment of NMR samples in aqueous media: verification with residual quadrupolar splittings in (23)Na and (133)Cs spectra

NMR spectra of (23)Na(+) and (133)Cs(+) in gelatine in a silicone rubber tube that was stretched to various extents showed remarkably reproducible resonance multiplicity. The relative intensities of the components of the split peaks had ratios, 3:4:3, and 7:12:15:16:15:12:7, respectively, that conformed with those predicted using a Mathematica program. The silicone-rubber tube was sealed at its lower end by a small rubber stopper and placed inside a thick-walled glass tube. Gelatine was injected in solution into the silicone tube and 'set' by cooling below 30 degrees C. A plastic thumb-screw held the silicone tube at various degrees of extension, up to approximately 2-fold. After constituting the gel in buffers containing NaCl and CsCl, both (23)Na and (133)Cs NMR spectroscopy revealed that after stretching the initial single Lorentzian line was split into a well-resolved triplet and a heptet, respectively. This was interpreted as being due to coupling between the electric quadrupoles of the nuclei and the average electric field gradient tensor of the collagen molecules of gelatine; these molecules became progressively more aligned in the direction of the main magnetic field, B(0), of the vertical bore magnet, as the gel was stretched. This apparatus provides a simple way of demonstrating fundamental physical characteristics of quadrupolar cations, some characteristics of gelatine under stretching, and a way to invoke static distortion of red blood cells. It should be useful with these and other cell types, for studies of metabolic and membrane transport characteristics that may change when the cells are distorted, and possibly for structural studies of macromolecules.