PREPARATION OF POLYALKYLCYANOACRYLATE NANOPARTICLES WITH VARIOUS MORPHOLOGIES

The effects of various reaction conditions on the preparation of polyalkylcyanoacrylate(PACA)nanoparticles are studied. The PACA nanoparticles with different crosslinking degrees and morphology arc prepared. Addition of crosslinkers can not only adjust the particle size,but also change the morphology of PACA nanoparticles. Moreover,the loose network structure of the PACA nanoparticles with "core/shell-like" morphology is investigated by AFM and TEM in detail.     

纳米CeO2的制备技术及应用

综述并评价了目前国内外有关纳米CeO2的多种制备方法及其特点。从CeO2的结构特点和功能特性出发着重介绍了纳米CeO2在汽车尾气净化、燃料电池、电化学反应、化学机械抛光及金属表面涂层等若干高科技领域中的应用研究进展,并提出了纳米CeO2研究的发展方向,为进一步深入研究和开发高性能新型CeO2功能纳米材料提供参考和借鉴。     

X射线荧光光谱分析技术在质量检测中的应用探讨

简要介绍了X射线荧光光谱分析技术原理、光谱仪类型及分析方法,阐述了X射线荧光光谱分析技术在质量检测中的应用,对X射线荧光光谱检测应用中仪器选型配置、样品制备方法选择、定量分析技术进行了探讨.     

沉淀法制备纳米粉体及其形貌控制

根据其应用来控制纳米粉末的形貌是制备纳米粉体十分关键的技术特征，本文讨论了沉淀法制备纳米粉末的特点及其形貌控制的措施，并对形貌控制的机理进行了探讨。     

Ultra-high sensitivity of rhodamine B sensing based on NaGdF4:Yb3+,Er3+@NaGdF4 core-shell upconversion nanoparticles

A series of mono-dispersed hexagon NaGdF_4:Yb~(3+),Er~(3+)@NaGdF_4 core-shell nanoparticles with different shell thickness were synthesized via a co-precipitation method. Nanoparticles with high upconversion fluorescent emissions result in large signal-to-noise ratio, which guarantees the accuracy of the sensitivity. Besides, the maximum sensitivity of these NPs as detection film increases first and then decreases with the shell thickness increasing. When the shell thickness is 2.3 nm(NaGdF_4-2), the maximum sensitivity(0.69959 ppm~(-1)) is reached. A large degree of overlap between the rhodamine B absorption band and the Er~(3+) green emission bands ensures that the NaGdF_4:Yb~(3+),Er~(3+)@NaGdF_4 nanoparticles can be used as fluorescent probe to detect the concentration of rhodamine B based on fluorescent intensity ratio technology. The linear relationship between the rhodamine B concentration and the intensity ratio(R) of green and red emission intensity(I_(S+H) and I_F) were studied systematically. The result shows that the maximum sensitivity can be obtained in low concentration rhodamine B(4 ppm), which is lower than the reported minimum detection concentration. Thus, the ultra-high sensitivity detection by NaGdF_4:Yb~(3+),Er~(3+)@NaGdF_4 core-shell upconversion nanoparticles in low concentration can be realized,which provides promising applications in bio-detection filed.     

Development of ciprofloxacin-loaded nanoparticles: physicochemical study of the drug carrier

This paper describes the optimization of the preparation of ciprofloxacin-loaded polyethylbutylcyanoacrylate (PEBCA) nanoparticles. The association of ciprofloxacin with nanoparticles was performed by emulsion polymerization, but successful entrapment was only obtained in the presence of acetone in the polymerization medium. This preparation process led to a stable ciprofloxacin nanoparticle suspension, with a mean size value twice as high as that obtained in the absence of drug, and an association efficiency of 82%. Moreover, the molecular weight value of ciprofloxacin nanoparticles was shown to be reduced as compared with unloaded nanoparticles. Drug release from the colloidal carrier in medium containing esterase was found to be very slow (a maximum of 51.5% after 48 h), suggesting that this release resulted from bioerosion of the polymer matrix. Interestingly, it was observed that 30.5% of the initial amount of ciprofloxacin was not detectable by HPLC analysis after nanoparticle preparation and corresponded either to ciprofloxacin covalently bound to PEBCA or to ciprofloxacin chemically degraded during the polymerization process. 19F-NMR analysis demonstrated that ciprofloxacin entrapped into nanoparticles was only in its neutral form. The measurements of molecular weight suggest the participation of the antibiotic as an anionic polymerization initiator, leading to the formation of a chemical bond between some of the drug and the polymer. These data allowed us to propose a model describing the association of ciprofloxacin with PEBCA nanoparticles obtained by emulsion polymerization.     

超声-化学沉淀法制备WO_3纳米颗粒研究

采用超声-化学沉淀法制备了WO3纳米颗粒,通过X射线粉末衍射谱(XRD)、X光能谱分析(EDX)、透射电子显微镜(TEM)和场发射扫描电子显微镜(FE-SEM)等测试手段对产物进行了表征。结果表明,所制备的淡黄色WO3纳米颗粒纯度高,平均粒径在40nm左右,呈类球形;讨论了超声条件、无水乙醇的使用、沉淀的分离洗涤与干燥以及煅烧条件等因素对制备WO3纳米颗粒的影响。     

化学还原法制备非晶态合金纳米粉末研究进展

简要介绍了用化学还原法制备非晶合金纳米粉末的具体步骤。重点讨论了制备二元非晶粉末的反应机理以及还原剂的浓度、加入顺序、加入速度、反应温度、反应溶液的初始pH值等工艺因素对产物成分和性能的影响。并对制备三元及三元以上的非晶合金纳米粉末的研究进展作了简要介绍;对该领域今后需要重点研究的一些理论问题进行了归纳。     

Poly(vinyl alcohol) nanoparticles prepared by freezing-thawing process for protein/peptide drug delivery

Poly(vinyl alcohol) (PVA) hydrogel nanoparticles have been prepared by using a water-in-oil emulsion technology plus cyclic freezing-thawing process. The PVA hydrogel nanoparticles prepared by this method are suitable for protein/peptide drug delivery since formation of the hydrogel does not require crosslinking agents or other adjuvants and does not involve any residual monomer. Particularly, there is no emulsifier involved in this new method. Bovine serum albumin (BSA), as a model protein drug, is incorporated into the PVA hydrogel nanoparticles. The PVA hydrogel nanoparticles possess a skewed or log-normal size distribution. The average diameter of the PVA hydrogel nanoparticles is 675.5+/-42.7 nm. Protein drug loading efficiency in the PVA hydrogel nanoparticles is 96.2+/-3.8%. The PVA hydrogel nanoparticles swell in an aqueous solution and the swelling degree increases with the increase of temperature. In vitro release studies show that the BSA release from the nanoparticles can be prolonged to 30 h. The BSA release follows a diffusion-controlled mechanism. The number of freezing-thawing cycle and release temperature both influence BSA release rate considerably. Less freezing-thawing cycle or higher release temperature leads to faster drug release. The BSA is stable during preparation of the PVA hydrogel nanoparticles.     

Green mediated synthesis of lanthanum doped zinc oxide: Study of its structural,optical and latent fingerprint application

The present paper summarises the synthesis of La³⁺ doped zinc oxide nanoparticles using Aloe vera gel by solution combustion method and the characterization using a powder X-ray diffractometer (PXRD), a transmission electron microscope (TEM), an X-ray photometric spectrometer (XPS), a Raman spectrometer and their applications in optical devices and latent fingerprinting. PXRD pattern confirms the crystallite size of La³⁺ doped ZnO varies from 13 to 20 nm. Crystallite size varies inversely with doping concentration. Photoluminescence properties are found to be the maximum for 2 mol% doping concentration. PL spectra extends the use of ZnO:La³⁺ nanoparticles in blue green LED. These nanoparticles also have superior property as a fluorescent labels in fingerprints.     

纳米二硫化钼制备过程中硫源及分散剂的研究

纳米二硫化钼具有优异的性能,其应用前景广阔。制备纳米二硫化钼粉末的方法很多,特点各异,并各有其优缺点。液相还原法制备纳米二硫化钼因具有实验设备简单、操作方便、流程短和制得的颗粒粒径较小等优点近年来受到广泛的关注。本文通过对应用该法制备非晶态二硫化钼过程中的收率、粒径和形貌的分析,确定了制备过程的最佳硫源和分散剂分别为硫代乙酰胺和聚乙二醇。     

Up-conversion fluorescence biosensor for sensitive detection of CA-125 tumor markers

Sensitive and specific bioassays of tumor markers are critical for early cancer detection and treatment. In recent years, lanthanide(Ln~(3+)) doped upconversion nanoparticles(UCNPs) have attracted wide attentions in tumor markers detectio n. Herein, we co mbined NaYF_4:Yb,Tm and silver nanoparticles, serving as energy donor and receptor, respectively, to form an up-conversion fluorescence based inhibitory tumor marker biosensor system. The tumor marker CA-125 molecules are labeled with silver NPs, and the energy transfer fluorescent signal can be detected between the UCNPs and the silver NP receptors. The biosensor shows good stability, high sensitivity and selectivity in the tumor marker concentration range from 5 to 100 ng/mL, as well as a detection limit of 120 pg/mL. Due to the advantage of ease of fabrication and operation, low cost and high information capacity, this technology holds great potential for the clinical applications.     

Long-circulating nanoparticles bearing heparin or dextran covalently bound to poly(methyl methacrylate)

PURPOSE: In a biomimetic approach to the development of drug carriers escaping early capture by phagocytes, nanoparticles made of amphiphilic copolymers of either heparin or dextran and methyl methacrylate were evaluated relative to their in vivo blood circulation time. They were compared to bare PMMA nanoparticles. METHODS: Owing to the fluorescent properties of the covalently attached N-vinyl carbazole, the particles could be detected directly in mouse plasma. Samples were drawn at different time intervals and fluorescence was recorded. RESULTS: After an initial phase of elimination from the blood with a half-life of 5 h, the remaining heparin nanoparticles circulated for more than 48 h and were still detectable in the plasma at 72 h. Dextran nanoparticles were also eliminated very slowly over 48 h. Bare poly (methyl methacrylate) nanoparticles were found to have a half-life of only 3 min. CONCLUSIONS: Both types of nanoparticles proved to be long-circulating. The potent capacity for opsonisation of the poly(methyl methacrylate) core were hidden by the protective effect of either polysaccharide, probably due to a dense brush-like structure. In the case of heparin nanoparticles, the "stealth" effect was probably increased by its inhibiting properties against complement activation.     

Local intraluminal infusion of biodegradable polymeric nanoparticles. A novel approach for prolonged drug delivery after balloon angioplasty

BACKGROUND: Several perfusion balloon catheters are under investigation for local drug delivery; however, sustained tissue drug levels are difficult to achieve with these techniques. To overcome this problem, sustained-release, biodegradable nanoparticles represent a potential alternative for prolonged local delivery. METHODS AND RESULTS: A biodegradable polylactic-polyglycolic acid (PLGA) copolymer was used to formulate nanoparticles. Fluorescent-labeled nanoparticles were intraluminally administered in a single, 180-second infusion after balloon injury in the rat carotid model. Localization and retention at different time points and biocompatibility of nanoparticles were evaluated. To evaluate the potential of the system in the prevention of neointimal formation, dexamethasone was incorporated into the particles and delivered locally as above. Nanoparticles were seen in the three layers of the artery at 3 hours and 24 hours. At 3 days, they were mainly present in the adventitial layer, decreasing at 7 days, with no fluorescent activity at 14 days. The PLGA nanoparticles appeared to be fully biocompatible. In the dexamethasone nanoparticle study, a significant amount of dexamethasone was present in the treated segment for up to 14 days after a single infusion, with no plasma levels detected after the first 3 hours. There was a 31% reduction in intima-media ratio in animals treated with local dexamethasone nanoparticles compared with control. CONCLUSIONS: Nanoparticles successfully penetrated into the vessel wall and persisted for up to 14 days after a short, single intraluminal infusion. Local administration of nanoparticles with incorporated dexamethasone significantly decreased neointimal formation. This methodology appears to have important potential for clinical applications in local drug delivery.     

Identification of particular epithelial areas and cells that transport polypeptide-coated nanoparticles in the nasal respiratory mucosa of the rabbit

The active transcytosis of many different polypeptides (either presented free or adsorbed on latex nanoparticles), found in the respiratory mucosa of the upper nasal concha, has previously been shown to be proportional to the total volume of the lymphoid aggregates present in the tissue. By combining the use of fluorescent nanoparticles, flux measurements, confocal and scanning electron microscopy and conventional histology, it is shown in this paper that: (i) the areas of epithelium overlying lymphoid aggregates are the only transporting polypeptides; (ii) the respiratory epithelium in these areas consists mainly of non-ciliated microvillar cells, with numerous ciliated cells and rare mucous goblet cells at the periphery of the area only; (iii) non-ciliated microvillar cells are distinguishable in cells with well developed finger-like microvilli and cells with an irregularly pleated apical membrane, similar to that of intestinal and bronchial antigen-sampling M-cells; (iv) groups of polypeptide-coated nanospheres are found bound to this latter type of cells, demonstrating that these are the transporting cells, detected at the first stage of the transcytotic cycle.     

Development of physicochemical foundations for the synthesis of tungsten-based nanopowders with controlled properties

A chemical and metallurgical method for the preparation of alloyed tungsten-based nanopowders has been developed. The synthesis conditions providing the formation of tungsten-based nanopowders with a specified complex of properties are determined. The chemical and phase compositions and the sizes of nanoparticles and agglomerates of the alloyed tungsten-based nanopowders are studied.     

Luminescent and magnetic properties of multifunctional europium(III) complex based nanocomposite

The luminescent rare earth (RE) complex based multifunctional nanocomposites offer new potential applications of multimodal imaging (magnetic resonance imaging (MRI), fluorescent bioimaging, etc.) that can be associated with therapeutic activities. In this study, we report some results obtained with novel multifunctional Fe₃O₄/Si-amine/Eu(NTA)₃ nanocomposites that are composed of europium(III) complex with 1-(2-naphthoyl)-3,3,3-trifluoroacetone ligands (NTA) (Eu(NTA)₃) and superparamagnetic Fe₃O₄ nanoparticles. These nanocomposites were functionalized with an amine group for biomedicine application. The multifunctional Fe₃O₄/Si-amine/Eu(NTA)₃ nanocomposites exhibit both good magnetic behavior of Fe₃O₄ nanoparticles as a core and strong fluorescent property of europium(III) complex. Their characterizations were analyzed by XRD, SEM, EDX and FTIR spectra. The optical properties were studied in detail by UV-VIS spectra and luminescent emission spectra. The magnetic property was estimated by VMS. The effect of concentrations of luminescent Eu(NTA)₃ complex on luminescent and magnetic properties is discussed.     

Low-temperature electrochemical synthesis and characterization of ultrafine Y（OH）_3 and Y_2O_3 nanoparticles

Ultrafine Y(OH)3 nanoparticles were successfully deposited from an additive-free 0.005 mol/L YCl3 low-temperature bath on the steel cathode at the current density of 0.5 mA/cm2 and bath temperature of 10 oC. Heat treatment of the prepared Y(OH)3 nanoparticles at 600 oC in air led to the formation of Y2O3 nanoparticles. Thermal behavior and phase transformation during the heat treatment of Y(OH)3 were investigated by differential scanning calorimetry (DSC) and thermogramimetric analysis (TGA). The morphologies, crystal structures and compositions of the prepared materials were examined by means of scanning and transmission electron microscopy (SEM and TEM) as well as X-ray diffraction (XRD) and FT-IR spectroscopy. The results showed that the prepared Y(OH)3 nanoparticles was essentially amorphous and composed of well dispersed ultrafine particles with size of 4 nm. After heat treatment, the obtained oxide product was well crystallized cubic phase of Y2O3 nanoparticles with the grain size of around 5 nm. It was concluded that low-temperature cathodic electrodeposition offered a facile and feasible way for preparation of ultrafine Y(OH)3 and Y2O3 nanoparticles.     

PACAP(6-38) inhibits the growth of prostate cancer cells

The human recombinant granulocyte colony-stimulating factor (rhG-CSF) is largely used in the treatment of neutropenia occurring during chemotherapy. After injection, this glycoprotein distributes through the whole body. Thus, to obtain high and durable bone marrow concentrations, targeting with polyalkylcyanoacrylate nanoparticles was considered. Two methods of preparation were investigated: anionic polymerization and precipitation of the preformed polymer. By anionic polymerization, it was possible to associate more than 66% of rhG-CSF with nanoparticles (polyisobutyl- or polyisohexylcyanoacrylate nanoparticles) when the glycoprotein was added at the end of the polymerization process. It has been shown that the rhG-CSF was mainly adsorbed on the surface of the nanoparticles and most of the colony stimulating activity was conserved. Using precipitation of performed polyisohexylcyanoacrylate, 90% of rhG-CSF was associated with nanoparticles, the protein being mainly adsorbed onto the nanoparticle surface. In this case, a decrease of the colony stimulating activity was however observed. Whatever the method used, the in vitro release of rhG-CSF from the polyisohexylcyanoacrylate nanoparticles, was progressive during 8 h in seric conditions. Nevertheless, using mice as an animal model, it has been shown that the short-term effects of intravenously injected rhG-CSF were not increased by its association with polyisohexylcyanoacrylate nanoparticles.     

Encoding, repetition, and the mirror effect in recognition memory: symmetry in motion

The entrapment of loperamide hydrochloride (LPM) in biodegradable polymeric drug carriers such as nanoparticles might enable its passage across the blood-brain barrier. The optimization of the preparation of the LPM-loaded PLA nanoparticles was performed employing high pressure emulsification-solvent evaporation. The resulting nanoparticles were characterized by particle size, distribution, thermal analysis, and drug release profiles. The partition of LPM into the organic phase increased with an increase in pH of the aqueous phase and with addition of lipophilic surfactants such as sorbitan fatty acid esters, resulting in an increase in the drug entrapment in the nanoparticles. Evaporation of the organic phase under reduced pressure and the addition of ethanol in the organic phase yielded a high drug entrapment due to the rapid polymer precipitation. The addition of the sorbitan fatty acid esters further increased the drug entrapment even at higher LPM concentrations. The results of thermal analysis suggest that LPM was homogeneously dispersed in the amorphous polymer matrix. The in vitro release of the drug from nanoparticles was biphasic, with a fast initial phase, followed by a second slower phase. Different drug release profiles from nanoparticles can be achieved by addition of sorbitan fatty acid esters, or the employment of different solvents as the organic phase.