Membrane cartridges for endotoxin removal from interferon preparations

The suitability of membrane cartridges for the removal of endotoxin from both distilled water and interferon preparations was examined. The endotoxin concentrations were reduced to 4.0 and 7.3 EU/ml, respectively, when about 4000 ml of distilled water with 20 and 28 EU/ml were passed through the deoxycholate and chitosan immobilized membrane cartridges. When 200 ml of interferon preparation with endotoxin concentration more than 80 EU/ml and pH 3.9 were applied to a deoxycholate immobilized membrane cartridge at a flow-rate of 9 ml/min, the endotoxin concentration was reduced to less than 10 EU/ml. However, if an interferon preparation of 450 ml, with more than 80 EU/ml of endotoxin and pH 3.9 was applied to the chitosan immobilized membrane cartridge at a flow-rate of 18 ml/min, the endotoxin concentration was reduced to less than 10 EU/ml. (C) 2003 Elsevier Science B.V. All rights reserved.

Affinity membrane chromatography for the analysis and purification of proteins

Affinity chromatography is unique among separation methods as it is the only technique that permits the purification of proteins based on biological functions rather than individual physical or chemical properties. The high specificity of affinity chromatography is due to the strong interaction between the ligand and the proteins of interest. Membrane separation allows the processing of a large amount of sample in a relatively short time owing to its structure, which provides a system with rapid reaction kinetics. The integration of membrane and affinity chromatography provides a number of advantages over traditional affinity chromatography with porous-bead packed columns, especially with regard to time and recovery of activity. This review gives detailed descriptions of materials used as membrane substrates, preparation of basic membranes, coupling of affinity ligands to membrane supports, and categories of affinity membrane cartridges. It also summarizes the applications of cellulose/glycidyl methacrylate composite membranes for proteins separation developed in our laboratory. (C) 2001 Elsevier Science B.V. All rights reserved.

Selective hydrogenation of cyclopentadiene in mono- and bimetallic catalytic hollow-fiber reactors

The mono- and bimetallic catalytic polymeric hollow-fiber reactors were established with catalytic polymeric cellulose acetate (CA) hollow fibers prepared by supporting the polymer-anchored mono- or bimetallic catalyst in/on the inner wall of the hollow fibers. The selective hydrogenation of cyclopentadiene to cyclopentene was efficiently carried out in the above catalytic polymeric hollow-fiber reactors, especially in the NaBH4 reduced bimetallic PVP-Pd-0.5Co/CA hollow-fiber reactor under mild conditions of 40 degrees C and 0.1 MPa. It was found that there was a remarkable synergic effect of palladium and cobalt reduced by NaBH4 in the bimetallic PVP-Pd-0.5Co/CA hollow-fiber reactor, which results in a 97.5% conversion of cyclopentadiene and a 98.4% selectivity for cyclopentene. (C) 2000 Elsevier Science B.V. All rights reserved.

Anti-inflammatory and immunomodulatory activities of polysaccharide from Chlorella stigmatophora and Phaeodactylum tricornutum

Crude polysaccharide extracts were obtained from aqueous extracts of the microalgae Chlorella stigmatophora and Phaeodactylum tricornutum. The crude extracts were fractionated by ion-exchange chromatography on DEAE-cellulose columns. The molecular weights of the polysaccharides in each fraction were estimated by gel filtration on Sephacryl columns. The crude polysaccharide extracts of both microalgae showed anti-inflammatory activity in the carrageenan-induced paw edema test. In assays of effects on the delayed hyper-sensitivity response, and on phagocytic activity assayed in vivo and in vitro, the C. stigmatophora extract showed immunosuppressant effects, while the P. tricornutum extract showed immunostimulatory effects. Copyright © 2003 John Wiley & Sons, Ltd.

Surface-enhanced Raman scattering from surfactant-free 3D gold nanowire networks substrates

A useful method for the fabrication of three-dimensional gold nanowire networks based on the chemical reduction of HAuCl4 with trisodium citrate was presented. The coverage of the 3D gold nanowire networks was tunable by altering precursor concentration. The as-prepared 3D gold nanowire networks could be used as surface-enhanced Raman scattering (SERS) substrates and examined by 4-aminothiophenol (4-ATP) as a probe molecules.

DNAzyme-based Colorimetric Sensing of Lead (Pb2+) Using Unmodified Gold Nanoparticle Probes

Novel functional oligonucleotides, especially DNAzymes with RNA-cleavage activity, have been intensively studied due to their potential applications in therapeutics and sensors. Taking advantage of the high specificity of 17E DNAzyme for Pb2+, highly sensitive and selective fluorescent, electrochemical and colorimetric sensors have been developed for Pb2+. In this work, we report a simple, sensitive and label-free 17E DNAzyme-based sensor for Pb2+ detection using unmodified gold nanoparticles (GNPs) based on the fact that unfolded single-stranded DNA could be adsorbed on the citrate protected GNPs while double-stranded DNA could not. By our method the substrate cleavage by the 17E DNAzyme in the presence of Pb2+ could be monitored by color change of GNPs, thereby Pb2+ detection was realized.

Investigation of some critical parameters of buffer conditions for the development of quantum dots-based optical sensors

The unique surface-sensitive properties make quantum dots (QDs) great potential in the development of sensors for various analytes. However, quantum dots are not only sensitive to a certain analyte, but also to the surrounding conditions. The controlled response to analyte may be the first step in the designing of functional quantum dots sensors. In this study, taking the quenching effect of benzoquinone (BQ) on CdTe QDs as model, several critical parameters of buffer solution conditions with potential effect on the sensors were investigated. The pH value and the concentration of sodium citrate in the buffer solution critically influenced the quenching effects of BQ.

Two-dimensional beta-NaLuF4 hexagonal microplates

A simple hydrothermal method has been developed to synthesize monodisperse beta-NaLuF4 microplates in a large scale. The microcrystals have a perfect hexagonal shape with a diameter of about 5.2 mu m and a thickness of 300 nm. Trisodium citrate (Cit(3-)), which is introduced into the reaction mixture and acts as the chelating agent and shape modifier, plays a key role in fine-tuning the microstructures. The dominant adsorption of Cit(3-) onto the {0001} facets lowers the surface energy of these facets.

Rapid fabrication of Au nanoparticle films with the aid of centrifugal force

In this work, rapid fabrication of Au nanoparticle (Au NP) films has been simply achieved by alternate adsorption of citrate-stabilized Au NPs and poly(diallyldimethylammonium chloride) with the aid of centrifugal force. In contrast to conventional electrostatic assembly, we carried out the assembly process in a centrifuge with a rotating speed of 4000 rpm, where centrifugal force can be imposed on Au NPs. Scanning electron microscopy and cyclic voltammetry were employed to characterize the assembly procedure and the thus-prepared thin solid films. Our results demonstrate that centrifugal force can promote the assembly of Au NPs and therefore enable the rapid fabrication of functional Au NP films.

Preparation of Polyacrylamide Aqueous Dispersions Using Poly(sodium acrylic acid) as Stabilizer

High-solids, low-viscosity, stable polyacrylamide (PAM) aqueous dispersions were prepared by dispersion polymerization of acrylamide in aqueous solution of ammonium sulfate (AS) using Poly (sodium acrylic acid) (PAANa) as the stabilizer, ammonium persulfate (APS) or 2,2'-Azobis (N,N'-dimethyleneisobutyramidine) dihydrochloride (VA-044) as the initiator. The molecular weight of the formed PAM, ranged from 710, 000 g/mol to 4,330,000 g/mol, was controlled by the addition of sodium formate as a conventional chain-transfer agent. The progress of a typical AM dispersion polymerization was monitored with aqueous size exclusion chromatography. The influences, of the AS concentration, the poly(sodium acrylic acid) concentration, the initiator type and concentration, the chain-transfer agent concentration and temperature Oil the monomer conversion, the dispersion viscosity, the PAM molecular weight and distribution, the particle size and morphology were systematically investigated.

Controlled Synthesis of Ln(3+) (Ln = Tb, Eu, Dy) and V5+ Ion-Doped YPO4 Nano-/Microstructures with Tunable Luminescent Colors

YPO4 nano/microcrystals with multiform crystal phases and morphologies, such as hexagonal nano/submicroprisms, spherical-like nanoparticles, and nanorods with different length/diameter ratios as well as tetragonal nanospindles, have been synthesized via a facile hydrothermal route. A series of controlled experiments indicate that the pH values in the initial solution, phosphorus sources, and the organic additive trisodium citrate (Cit(3-)) are responsible for crystal phase and shape determination of final products. It is found that Cit(3-) as a ligand and shape modifier has the dynamic effect by adjusting the growth rate of different facets under different experimental conditions, resulting in the formation of various geometries of the final products. The possible formation mechanisms for products with diverse architectures have been presented.

Architectures of Strontium Hydroxyapatite Microspheres: Solvothermal Synthesis and Luminescence Properties

Strontium hydroxyapatite (Sr-5(PO4)(3)OH, SrHAp) microspheres with 3D architectures have been successfully prepared through a efficient and facile solvothermal process. The experimental results indicate that the SrHAP microspheres are composed of a large amount of nanosheets, which are assembled in a radial form from the center to the surface of the microspheres. The as-obtained SrHAp samples show an intense and bright blue emission from 350 to 570 nm centered at 427 nm (CIE coordinates: x = 0.153, y = 0.081; lifetime: 9.2 ns; quantum efficiency: 31%) under long-wavelength UV light excitation (344 nm). This blue emission might result from the CO2 center dot- radical impurities in the crystal lattice. Furthermore, the surfactants CTAB and trisodium citrate have an obvious impact on the morphologies and the luminescence properties of the products, respectively.

LaF3, CeF3, CeF3 : Tb3+, and CeF3 : Tb3+@LaF3 (core-shell) nanoplates: Hydrothermal synthesis and luminescence properties

LaF3. CeF3, CeF3:Tb3+, and CeF3:Tb3+ @LaF3 (core-shell) 2D nanoplates have been successfully synthesized by a facile and effective hydrothermal process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. The experimental results indicate that the organic additive, trisodium citrate (Cit(3-)), as a shape modifier has the dynamic effect by adjusting the growth rate of different crystal facets, resulting in forming the anisotropic geometries of the final products. The possible formation mechanisms for different products have been presented. The CeF3, CeF3:Tb3+, and CeF3:Tb3+ @LaF3 (core/shell) nanoplates show characteristic emission of Ce3+ (5d-4f) and Tb3+ (f-f), respectively.

Gold nanowire assembling architecture for H2O2 electrochemical sensor

Morphological control of nanomaterials is of great interest due to their size and shape-dependent chemical and physical properties and very important applications in many fields such as biomedicine, sensors, electronics and others. In this paper, we reported a simple strategy for synthesizing gold nanowire assembling architecture at room temperature. It is found that two important factors, the proper volume ratio of ethanol to water and poly(vinyl pyrrolidone) (PVP), will play important roles in synthesizing flower-like short gold nanowire assembling spheres. Furthermore, the obtained flower-like gold assembling spheres with high surface-to-volume ratio have been employed as enhancing materials for electrochemical sensing H2O2. The present electrochemical sensing platform exhibited good electrocatalytic activity towards the reduction of H2O2. The detection limit for H2O2 was found to be 1.2 mu M, which was lower than certain enzyme-based biosensors.

One-Step Synthesis of Folic Acid Protected Gold Nanoparticles and Their Receptor-Mediated Intracellular Uptake

We report here a facile method to obtain folic acid (FA)-protected gold nanoparticles (Au NPs) by heating an aqueous solution of HAuCl4/FA in which FA acts as both the reducing and stabilizing agent. The successful formation of FA-protected Au NPs is demonstrated by UV/Vis spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). ne intracellular uptake of these nanoparticles is facilitated by HeLa cells overexpressing the folate reporter, which itself is significantly inhibited by free FA in a competitive assay as quantified by inductively coupled plasma mass spectroscopy (ICP-MS). This simple one-step approach affords a new perspective for creating functional nanomaterials, and the resulting biocompatible, functional Au NPs may find some prospective applications in various biomedical fields.