Time-resolved EPR investigation on the photoreactions of vitamin K with antioxidant vitamins in micelle systems

The photochemical reactions of vitamin K (VK) with antioxidant vitamins (vitamin E (VE) and vitamin C (VC)) in aqueous hexadecyltrimethylammonium chloride (CTAC), sodium dodecyl sulfate (SDS), and Triton X-100 micelle systems, and in an aerosol OT (AOT) reversed micelle system were investigated by a time-resolved EPR (TR-EPR). The photolysis of VK with VE in the aqueous micelle solutions gave the TR-EPR spectra having strong intensity and net emissive polarization, suggesting that the excited triplet state of VK (³VK^*) was rapidly quenched by VE coexisting inside the micelle. On the other hand, the photolysis of VK with VC in the aqueous SDS and CTAC micelle systems gave the spectra having weak intensity, showing that the reaction between ³VK^* and VC was inefficient in these micelle systems, probably because ³VK^* scarcely diffused out from the micelle. The photolysis of VK with VC in the AOT reversed micelle solution gave the spin-correlated radical pair CIDEP spectrum. The result suggests that the long-lived radical pair was generated from the reaction between ³VK^* and VC in the water/oil interface region of the AOT micelle, although one of the reactants dissolved in the oil phase and another did in the separated water phase.     

Formation and stability of dispersed particles composed of vitamin K1, soybean oil and phosphatidylcholine

The purpose of this study was to develop an intravenous formulation composed of vitamin K₁ (VK) for the treatment of blood coagulation with warfarin-induced hypoprothrombinaemia. VK was dispersed using sonication with soybean phosphatidylcholine (PC) and the dispersion mechanism was evaluated by characterizing the dispersed particles with dynamic light scattering, fluorescence spectroscopy and surface monolayer techniques. VK has an appreciable solubility in PC bilayers (approximately 20 mol%). Within the VK molar fraction of 0.1–0.9, the size of the dispersed particles increased at room temperature within 3 months. By addition of soybean oil (SO) to VK (molar ratio of VK:SO=1:1), the solubility of the VK/SO mixtures in PC bilayers was decreased (approximately 5 mol%). The size of the aqueous dispersions at molar fractions of 0.1–0.7 was 50–70 nm and did not change for 3 months at room temperature. The solubility of the VK and VK/SO in PC bilayers is crucially important in the production of the stable aqueous dispersions of VK particles. Received: 1 August 2000 Accepted: 20 December 2000     

Study on vitamin K3-cyclodextrin inclusion complex and analytical application

The inclusion interaction of the complexes between Vitamin K(3) (VK(3)) and beta-cyclodextrin (beta-CD), hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and sulfobutylether-beta-cyclodextrin (SBE-beta-CD) were studied by using steady-state fluorescence measurements. The various factors affecting the inclusion process were examined in detail. The formation constants and inclusion stoichiometry for VK(3)-CDs were determined. The results showed that the inclusion ability of beta-CD and its derivatives was the order: SBE-beta-CD>HP-beta-CD>beta-CD. The related inclusion mechanism is proposed to explain the inclusion process. A method of determining VK(3) was established with the linear range was 2.5 x 10(-6)-5.0 x 10(-4) M, and was used to determine the VK(3) tablets. The recoveries were in the range of 97.52-103.5%. The results were satisfactory.     

Spectrofluorimetric study on the inclusion interaction between vitamin K3 with p-(p-sulfonated benzeneazo)calix[6]arene and determination of VK3

The characteristics of host-guest complexation between p-(p-sulfonated benzeneazo) calix[6]arene (SBC6A) and vitamin K3 (VK3) were investigated by fluorescence spectrometry. A 1:1 stoichiometry for the complexation was established and was verified by Job's plot. An association constant of 4.95 x 10(3)L mol(-1) at 20 degrees C was calculated by applying a deduced equation. The interaction mechanism of the inclusion complex was discussed. It was found that the fluorescence of SBC6A could be remarkably quenched by an appropriate amount of VK3 especially when non-ionic surfactant Triton X-100 existed. According to the obtained results, a novel sensitive spectrofluorimetric method for the determination of VK3 based on supramolecular complex was developed with a linear range of 5.0 x 10(-7) -3.0 x 10(-5)mol L(-1) and a detection limit of 2.0 x 10(-7)mol L(-1). The proposed method was used to determine VK3 in commercial preparations with satisfactory results.     

Phagocytosis of PLGA microparticles in rat peritoneal exudate cells: a time-dependent study.

With the purpose of enhancing the efficacy of microparticle-encapsulated therapeutic agents, in this study we evaluated the phagocytic ability of rat peritoneal exudate cells and the preferential location of poly(d,l-lactide-co-glycolic acid) (PLGA) microparticles inside these cells. The microparticles used were produced by a solvent evaporation method and were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Size distribution analysis using DLS and SEM showed that the particles were spherical, with diameters falling between 0.5 and 1.5 mum. Results from cell adhesion by SEM assay, indicated that the PLGA microparticles are not toxic to cells and do not cause any distinct damage to them as confirmed by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. Among the large variety of cell populations found in the peritoneal exudates (neutrophils, eosinophils, monocytes, and macrophages), TEM showed that only the latter phagocytosed PLGA microparticles, in a time-dependent manner. The results obtained indicate that the microparticles studied show merits as possible carriers of drugs for intracellular delivery.     

Facile fabrication of long alpha-Fe(2)O(3), alpha-Fe and gamma-Fe(2)O(3) hollow fibers using sol-gel combined co-electrospinning technology

Long alpha-Fe(2)O(3) hollow fibers have been prepared through a facile sol-gel combined co-electrospinning technique using ferric citrate as precursor, and alpha-Fe and gamma-Fe(2)O(3) hollow fibers have been obtained by reduction and reoxidation at different conditions. The outer diameter of the as-prepared hollow fibers is 0.5-5 microm with wall thickness of 200-800 nm. The obtained tubular fibers were characterized by thermal gravimetric (TG), FT-IR spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Raman techniques. In addition, magnetic properties of alpha-Fe and gamma-Fe(2)O(3) hollow fibers have also been investigated.     

碳纳米管-TiO_2修饰电极伏安法测定维生素K_3

利用碳纳米管、二氧化钛两种纳米材料制成碳纳米管-TiO2复合膜修饰电极,进行了维生素K3电化学行为的研究。维生素K3在碳纳米管-TiO2复合膜修饰电极的电化学响应优于碳纳米管修饰电极,表明前者具有更好的催化作用。通过条件实验的优化,结果表明维生素K3在pH=9.42的氨水-NH4Cl底液中,富集时间为10s,富集电位于-0.60V,扫描速度为0.1V/s时有稳定的灵敏的氧化还原峰。峰电流与维生素K3浓度在3.0×10-6～8.0×10-5mol/L范围内呈良好的线性关系,检出限为5.0×10-7 mol/L。考查了修饰电极的重现性,5次平行测量的RSD为1.78%。该方法用于片剂药品中维生素K3含量的测定,回收率在97.5%～102%之间。     

Vitamin K2 as a New Modulator of the Ceramide De Novo Synthesis Pathway

The aim of the study was to evaluate the influence of vitamin K2 (VK2) supplementation on the sphingolipid metabolism pathway in palmitate-induced insulin resistant hepatocytes. The study was carried out on human hepatocellular carcinoma cells (HepG2) incubated with VK2 and/or palmitic acid (PA). The concentrations of sphingolipids were measured by high-performance liquid chromatography. The expression of enzymes from the sphingolipid pathway was assessed by Western blotting. The same technique was used in order to determine changes in the expression of the proteins from the insulin signaling pathway in the cells. Simultaneous incubation of HepG2 cells with palmitate and VK2 elevated accumulation of sphinganine and ceramide with increased expression of enzymes from the ceramide de novo synthesis pathway. HepG2 treatment with palmitate and VK2 significantly decreased the insulin-stimulated expression ratio of insulin signaling proteins. Moreover, we observed that the presence of PA w VK2 increased fatty acid transport protein 2 expression. Our study showed that VK2 activated the ceramide de novo synthesis pathway, which was confirmed by the increase in enzymes expression. VK2 also intensified fatty acid uptake, ensuring substrates for sphingolipid synthesis through the de novo pathway. Furthermore, increased concentration of sphingolipids, mainly sphinganine, inhibited insulin pathway proteins phosphorylation, increasing insulin resistance development.     

Novel formulations of vitamins and insulin by nanoengineering of polyelectrolyte multilayers around microcrystals

Microcapsules loaded with vitamin K3 (VK3), biotin, or insulin were prepared by using a novel coating technology based on the layer-by-layer (LbL) deposition of oppositely charged polyelectrolytes onto microcrystal templates. This produced multilayered, polymeric shells of varying thickness around the crystalline cores. Dissolution of the core material (VK3 with ethanol, biotin with basic solution, and insulin with acidic solution), resulted in its release through the shells. Microelectrophoresis was employed to monitor the microcrystal coating process; confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) were used to verify multilayer coating and the formation of hollow polymer shells following removal of the microcrystal templates. The release rates of both VK3 and insulin decreased as the wall thickness (the number of polyelectrolyte layers deposited onto the microcrystal cores), increased. The release time could be varied by a factor of more than ten, depending on the number of polyelectrolyte layers applied. Following the addition of 70 mass % ethanol, the solubility of VK3 increased by as much as 170-fold, resulting in an increased rate of VK3 release. By selecting appropriate polymer materials for the shells, and by controlling the number of polyelectrolyte layers applied, shells of various thickness, stiffness, aqueous solubility, dispersibility, biocompatibility, and permeability can be constructed.     

炭/多壁碳纳米管复合材料的制备与超级电容性能

结合环糊精包覆和热处理技术制备了炭/多壁碳纳米管(C/MWCNTs)复合材料, 并研究其应用于超级电容器的性能.利用扫描电子显微镜、透射电子显微镜、X射线衍射和拉曼光谱等技术对C/MWCNTs复合材料的形貌及结构进行分析.采用循环伏安和恒流充放电等电化学测试方法研究其电容特性.结果表明, C/MWCNTs复合材料具有良好的电化学性能, 远优于相应的炭及MWCNTs样品.在1 A/g电流密度下, 比电容可达到145 F/g, 循环3000次后, 容量无明显衰减.     

P3HT修饰一维有序壳核式CdS/ZnO纳米棒阵列复合膜的光电化学性能

采用电化学方法在铟锡氧化物(ITO)导电玻璃上制备了高度有序的ZnO纳米棒阵列, 在ZnO纳米棒阵列上先后电化学沉积CdS纳米晶膜及聚3-己基噻吩(P3HT)薄膜得到P3HT修饰的一维有序壳核式CdS/ZnO纳米阵列结构, 并通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、能量散射X射线(EDX)等表征手段证实了该结构的形成. 以此纳米结构薄膜为光阳极组装新型半导体敏化太阳电池, 研究了CdS纳米晶膜的厚度和P3HT薄膜的沉积对电池光伏性能的影响, 初步探讨了电荷在电池结构中的传输机理, 结果表明, CdS纳米晶膜和P3HT薄膜的沉积有效地拓宽了光阳极的光吸收范围, 实验中电池的光电转换效率最高达到1.08%.     

Spectrofluorimetric study of the beta-cyclodextrin:vitamin K3 complex and determination of vitamin K3

Vitamin K(3) (menadione) is an oil-soluble vitamin and not naturally fluorescent but yields fluorescence when it is reduced. However, it is possible to yield a fluorescent derivative in the region of 407 nm in aqueous medium when complexed to beta-cyclodextrin (CD). A 1:1 stoichiometric ratio and a formation constant of 373+/-34 l mol(-1) were obtained for the binary inclusion complex between menadione and beta-CD. The measurements were performed at pH 6.2 adjusted by adding 0.1 mol l(-1) citrate buffer solution and 6.4 x 10(-3) mol l(-1) of beta-CD concentration. The calibration graph was linear over the range 0.1-2.0 mg l(-1) with a repeatability of 2.2%; the detection limit was 0.022 mg l(-1) and the limit of quantification limit was 0.073 mg l(-1). The procedure was applied to pharmaceutical formulations.     

The use of optical microscopy to follow the degradation of isotactic polypropylene (iPP) subjected to natural and accelerated ageing

Microscopy and mechanical properties are commonly used to follow the changes in morphology and mechanical resistance, respectively, of materials before and after any type of treatment. In this work, we used light microscopy (LM), scanning electron microscopy (SEM) and measurement of the mechanical properties to assess the natural ageing of samples of isotactic polypropylene (iPP) in Campinas and after exposure to Weather-Ometer type accelerated ageing equipment. The results obtained for the mechanical properties and by light microscopy (LM) allowed us to identify the ageing time based on the amount of radiation, for a 50% loss of elongation at break. The results were similar for samples subjected to the two types of ageing processes. Although a simple technique, LM was considered efficient when compared with SEM and the measurement of mechanical properties.     

Incorporation of nanohydroxyapatite and vitamin D3 into electrospun PCL/Gelatin scaffolds: The influence on the physical and chemical properties and cell behavior for bone tissue engineering

Scaffold, an essential element of tissue engineering, should provide proper physical and chemical properties and evolve suitable cell behavior for tissue regeneration. Polycaprolactone/Gelatin (PCL/Gel)‐based nanocomposite scaffolds containing hydroxyapatite nanoparticles (nHA) and vitamin D3 (Vit D3) were fabricated using the electrospinning method. Structural and mechanical properties of the scaffold were determined by scanning electron microscopy (SEM) and tensile measurement. In this study, smooth and bead‐free morphology with a uniform fiber diameter and optimal porosity level with appropriate pore size was observed for PCL/Gel/nHA nanocomposite scaffold. The results indicated that adding nHA to PCL/Gel caused an increase of the mechanical properties of scaffold. In addition, chemical interactions between PCL, gelatin, and nHA molecules were shown with XRD and FT‐IR in the composite scaffolds. MG‐63 cell line has been cultured on the fabricated composite scaffolds; the results of viability and adhesion of cells on the scaffolds have been confirmed using MTT and SEM analysis methods. Here in this study, the culture of the osteoblast cells on the scaffolds showed that the addition of Vit D3 to PCL/Gel/nHA scaffold caused further attachment and proliferation of the cells. Moreover, DAPI staining results showed that the presence and viability of the cells were greater in PCL/Gel/nHA/Vit D3 scaffold than in PCL/Gel/nHA and PCL/Gel scaffolds. The results also approved increasing cell proliferation and alkaline phosphatase (ALP) activity for MG‐63 cells cultured on PCL/Gel/nHA/Vit D3 scaffold. The results indicated superior properties of hydroxyapatite nanoparticles and vitamin D3 incorporated in PCL/Gel scaffold for use in bone tissue engineering.     

Fe3O4 nanocrystals with novel fractal

Fe3O4 novel fractal nanocrystals have been synthesized by a surfactant-assisted solvothermal process for the first time. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), M?ssbauer spectroscopy (MS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the novel fractal nanocrystals. The lengths of the fractals are about 2-3 microm, and the trunks and branches of Fe3O4 fractals have almost the same diameters of ca. 30-50 nm. The roles of surfactant PEG-20000 and N2H4 have been discussed in detail. One key fact has been found that the ferrocene concentration has a vital effect on the morphologies of the products. The side-branching process and the oscillation of the concentration have been proposed to illustrate the formation mechanisms of the fractal nanocrystals. In addition, magnetic properties of Fe3O4 fractal nanocrystals have also been detected by a vibrating sample magnetometer, showing relatively high saturation magnetization (Ms) of ca. 78.75 emu/g.     

A luminescent and mesoporous core-shell structured Gd2O3 : Eu(3+)@nSiO2@mSiO2 nanocomposite as a drug carrier

In this paper, Gd(2)O(3) : Eu(3+) nanospheres have been encapsulated with nonporous silica and further layer of ordered mesoporous silica through a simple sol-gel process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N(2) adsorption/desorption, photoluminescence (PL) spectra, and kinetic decay were used to characterize the sample. The results indicate that the nanocomposite with general 50 nm shell thickness and 270 nm core size shows typical ordered mesoporous characteristics (2.4 nm) and has spherical morphology with a smooth surface and narrow size distribution. Additionally, the obtained inorganic nanocomposite shows the characteristic emission of Eu(3+) ((5)D(0)→(7)F(1-4)) even after the loading of drug molecules. The biocompatibility test on L929 fibroblast cells using MTT assay reveals low cytotoxicity of the system. Most importantly, the nanocomposite can be used as an effective drug delivery carrier. A typical anticancer drug, doxorubicin hydrochloride (DOX), was used for drug loading, and the DOX release, cytotoxicity, uptake behavior and therapeutic effects were examined. It was found that DOX is shuttled into the cell by the nanocomposite and released inside cells after endocytosis and that the DOX-loaded nanocomposite exhibited greater cytotoxicity than free DOX. These results indicate that core-shell structured Gd(2)O(3) : Eu(3+)@nSiO(2)@mSiO(2) nanocomposite has potential for drug loading and delivery into cancer cells to induce cell death.     

溴氧化紫外分光光度法测定维生素C和多酚

研究了同时测定维生素C和多酚的新方法。在体积分数38%和47.5%的乙醇、6×10-5mol/LBr2、2.5×10-3mol/LKI水溶液中,维生素C和多酚类的表观摩尔吸光系数(L.mol-1.cm-1)分别为5.42×104、8.22×105和5.46×104、8.60×105,维生素C和多酚的相对标准偏差(RSD)分别为2.5%、2.3%和2.1%、2.6%,该法用于绿豆芽、酸橙、未熟苹果、青椒中的维生素C和多酚含量测定,回收率为95.78%～100.7%。     

纳米晶状磷酸钙盐/Al2O3-Ti生物复合材料的制备与结构表征

0引言众所周知,钛及其合金具有优良的机械力学性能,但其生物活性不足。因此,在金属基体上涂敷一层生物活性涂层,结合金属与生物活性材料的各自优势,已成为世界各国学者研究最为活跃的生物复合材料体系之一。该体系可用于临床医学,作为人体硬组织等的修复替换材料。目前,已开发出多种在金属基体上制备生物活性涂层的工艺和方法。如:等离子沉积法[1]、离子束溅射法[2]、激光熔覆法[3]、溶胶鄄凝胶法[4]、电化学沉积与水热处理合成法[5]、电泳沉积[6]、电结晶[7]等多种方法。但现有涂层材料尚存在一些问题:(1)由于替换材料的高硬度而导致其周围硬组织坏死[8];(2)由于疲劳磨损或热膨胀不匹配引起涂层脱落[9];(3)由于异质相导致生物活性降解[10]。因此,研究新的制备工艺,开发新的生物复合材料体系就显得十分重要。考虑到Al2O3具有优异的抗磨损、耐腐蚀等性能,以及较好的生物相容性,常作为临床选用的人造硬组织承载材料[11],故在本研究工作中,我们首次采用阳极氧化与水热处理复合工艺研制酸式磷酸钙/Al2O3鄄Ti生物复合材料体系。该体系不同于由日本Ishizawa等研制的HAp/TiO2鄄Ti复合体系[12]。主要体现在两...     

Ce3+-Yb3+共掺CaF2纳米粒子的近红外发光

采用简单的水热方法制备了一系列Ce3+ -Yb3+共掺的CaF2纳米粒子.XRD测试结果表明,Ce3+和Yb3+不同掺杂浓度下的CaF2纳米粒子结晶良好.SEM和TEM分析表明,纳米粒子的平均粒径为30 nm左右.系统地研究了各样品的发光性质包括激发谱、紫外-可见发射谱、近红外发射谱和荧光寿命.激发Ce3+的5d能级,在900 ～ 1050 nm波长范围得到很强的近红外发射.随着Yb3离子浓度的增加,Ce3的发射强度降低,Yb3+的发射强度先升高后降低,Ce3+的寿命减少,能量传递效率增加.作为一个下转换光转换器,这种材料应用于硅基太阳能电池前端,能够减少电池热损失,增加电池转换效率.     

Characterization and biological evaluation of paclitaxel-loaded poly(L-lactic acid) microparticles prepared by supercritical CO2

In this study, paclitaxel loaded poly( L-lactic acid) (PTX-PLLA) microparticles were prepared using solution enhanced dispersion by supercritical CO2(SEDS) technique. This supercritical antisolvent technique offers the advantage of negligible organic solvent residua in the drug loaded microparticles. Scanning electron microscopy (SEM) showed that microparticles exhibited rather spherical shape and small particle size with narrow particle size distribution. X-ray diffraction (XRD) and differential scanning calorimeter (DSC) indicated that PTX was amorphously dispersed in the PLLA matrix. The drug loading and encapsulation efficiency of PTX-PLLA microparticles were 14.33% and 62.68%, respectively. In vitro cytotoxicity evaluation of PTX-PLLA microparticles against nonsmall-cell lung cancer A549 and ovarian cancer SKOV3 cell lines indicated that PTX-PLLA had superior antiproliferation activity against the A549 and SKOV3 cell lines, compared with free PTX formulations. The cellular internalization of fluorescent microparticles was evidenced by fluorescence microscope and further confirmed by transmission electron microscopy (TEM). This was attributed to the efficient intracellular accumulation of PTX via cell phagocytosis and sustained release of PTX from PLLA matrix. The anticancer activity of PTX-PLLA was associated with PTX-induced cell apoptosis such as nuclear aberrations, condensation of chromatin and swelling damage in mitochondria. The cell apoptosis index detected by flow cytometry was higher in PTX-PLLA group than in free PTX. The PTX-PLLA formulation, which was obtained through micronization of PTX and encapsulation of micronized PTX into PLLA simultaneously in the SEDS process, significantly potentiated the anticancer activity of PTX.