Protein A immobilized monolithic capillary column for affinity chromatography

Monolithic capillary columns for affinity chromatography were prepared by an in situ polymerization procedure using glycidyl methacrylate (GMA) as a monomer and trimethylolpropane trimethacrylate (TRIM) and ethylene dimethacrylate (EDMA) as cross-linkers, respectively. Scanning electron microscopy was applied to characterize the morphology of the end of monolithic capillary and mercury intrusion porosimetry to characterize the polymer rod prepared within the confines of a stainless steel column with 50 mm x 4.6 mm i.d. under the same polymerization condition. Obvious differences in the porous properties between the TRIM- and EDMA-based monoliths could be observed. Moreover, the mechanical stability of these two monolithic capillary columns was compared by testing the reproducibility of the column performance. The rod prepared with GMA and TRIM proved to be mechanically more stable than that prepared with GMA and EDMA. Protein A was immobilized on the monolithic rod for affinity chromatography and the experiments were performed on a capillary electrophoresis instrument, using its pressure system as the driving force. Non-specific adsorption was not observed on the TRIM-based affinity column, as proved with bovine serum albumin (BSA) as a test protein. The affinity column prepared with GMA and TRIM was then applied to determine the hIgG concentration in human serum. The correlative coefficient of the calibration curve reached 0.9942. The amount of adsorbed hIgG was unaffected by the flow rate of the loading buffer, which makes this method suitable for fast determination of biomacromolecules in microliter samples. (C) 2002 Elsevier Science B.V All rights reserved.

Bioactive, Luminescent and Mesoporous Europium-doped Hydroxyapatite as a Drug Carrier

Bioactive, luminescent and mesoporous europium-doped hydroxyapatite (Eu:HAp) was successfully prepared through a simple one-step route using cationic surfactant as template. The obtained multifunctional hydroxyapatite was performed as a drug delivery carrier to investigate the drug storage/release properties using ibuprofen (IBU) as a model drug

Solvothermal synthesis and characterization of Ln (Eu3+, Tb3+) doped hydroxyapatite

Luminescent Ln (Eu3+, Tb3+) doped hydroxyapatite (Eu:HAp, Tb:HAp) phosphors were successfully fabricated via the cetyltrimethylammonium bromide (CTAB)/n-octane/n-butanol/water microemulsion-mediated solvothermal process. The structure, morphology, and optical properties were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence (PL) spectra as well as the kinetic decays, respectively.

Microchip Micellar Electrokinetic Chromatography Based on One Functionalized Ionic Liquid and Its Excellent Performance on Proteins Separation

Herein, one water-soluble functionalized ionic liquid (IL), 1-butyl-3-methylimidazolium dodecanesulfonate (BAS), was designed, investigated and successfully applied to microchip micellar electrokinetic chromatography (MEKC) construction. It possessed the properties of both IL and surfactant. A fairly stable pH value similar to 7.4, which was fit to pH values of general biological buffers, was nicely placed at the optimum concentration of 20 mM BAS solution. While applying BAS solution as running buffer in poly(dimethylsiloxane) (PDMS) microfluidic systems, significantly enhanced electroosmotic flow (8-fold) and resolutions between analytes were obtained than that using other supporting electrolytes or surfactants.

Separation and detection of narcotic drugs on a microchip using micellar electrokinetic chromatography and electrochemiluminescence

A new approach for fast and sensitive electrochemiluminescence (ECL) detection of narcotic drugs on a microchip after separation by micellar electrokinetic chromatography (MEKC) is presented, taking the cocaine and its hydrolysate ecgonine as the test analytes. The mixture of hydrophilic BMIMBF4 ionic liquid (IL) and sodium dodecyl sulfate (SDS) was used directly as the buffer of MEKC with less noisy baselines, lower electrophoretic current and satisfactory separation performance.

Studies on the stability of diester-diterpenoid alkaloids from the genus Aconitum L. by high performance liquid chromatography combined with electrospray ionisation tandem mass spectrometry (HPLC/ESI/MSn)

The stability of diester-diterpenoid alkaloids (DDA) from plants of the genus Aconitum L. has been studied in different solvents and pH buffers. The HPLC/ESIMS method for analysing the concentration of DDA was established and DDA's decomposition products were elucidated by HPLC/ESI-MS/MSn. In different solvents, e.g. dichloromethane, ether, methanol and distilled water, the decomposition pathways of DDA are quite different and their difference in stabilities depends on the difference of their structures, in which substituents at the N atom and substituents at C-3 are different. The pyrolytic products of DDA, such as deacetoxy aconitine-type alkaloids, have been observed in the above solvents, whereas 8-methoxy-14-benzoyl aconitine-type alkaloids have been obtained only in methanol.

Identification of Phenylethanoid Glycosides in Plant Extract of Plantago asiatica L. by Liquid Chromatography-Electrospray Ionization Mass Spectrometry

The present work describes a liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method for rapid identification of phenylethanoid glycosides in plant extract from Plantago asiatica L. By using a binary mobile phase system consisting of 0.2% acetic acid and acetonitrile under gradient conditions, a good separation was achieved on a reversed-phase C-18 column. The [M-H](-) ions, the molecular weights, and the fragment ions of phenylethanoid glycosides were obtained in the negative ion mode using LC-ESI-MS. The identification of the phenylethanoid glycosides (peaks 1-3) in the extract of P. asiatica L. was based on matching their retention time, the detection of molecular ions, and the fragment ions obtained by collision-induced dissociation (CID) experiments with those of the authentic standards and data reported in the literature.

Analysis on Iridoid Glycosides in Crude and Processed Extracts from Cornus Officinals by Liquid Chromatography-electrospray Ionization Mass Spectrometry

The iridoid glycosides in crude and processed extracts from cornus officinals have been analyzed by high performance liquid chromatography-electrospray ionization mass spectrometry. Samples were analyzed by a reversed-phase C18 column using a binary eluent under gradient conditions. Seven iridoid glycosides could be separated and detected. The [M-H](-) ions of iridoid glycosides in the negative ion mode were observed, which reflect their molecule mass information. An in-source collision induced dissociation (in-source CID) experiment was carried out in order to identify the structures and to measure the contents of iridoid glycosides. The epimers were discovered in the experiment for the first time, namely 7 alpha-O-ethyl-morroniside and 7 beta-O-ethylmorroniside.

Analysis of Saponins from Leaves of Aralia elata by Liquid Chromatography and Multi-stage Tandem Mass Spectrometry

Four saponins were isolated from the leaves of Aralia elata, and established using NMR and other spectroscopic methods, as well as data reported in the literature. Three Aralia saponins from the leaves of Aralia elata sharing the same structures as those isolated from the root bark suggested that the leaves would be a good substitute for the root bark of Aralia elata. These four Aralia saponins were then extensively investigated using complementarily positive and negative electrospray ionization multistage tandem mass spectrometry (ESI-MSn). Two isomers of saponins with different sugar linkages were then successfully differentiated by positive ESI-MSn and verified with different retention times and the collision-induced dissociation (CID) spectra by LC-MS. A simple and effective LC-MS method was thus developed for the rapid identification and screening of these saponins in plant extracts from leaves of Aralia elata.

The nanocomposite scaffold of poly(lactide-co-glycolide) and hydroxyapatite surface-grafted with L-lactic acid oligomer for bone repair

Nanohydroxyapatite (op-HA) surface-modified with L-lactic acid oligomer (LAc oligomer) was prepared by LAc oligomer grafted onto the hydroxyapatite (HA) surface. The nanocomposite of op-HA/PLGA with different op-HA contents of 5, 10, 20 and 40 wt.% in the composite was fabricated into three-dimensional scaffolds by the melt-molding and particulate leaching methods. PLGA and the nanocomposite of HA/PLGA with 10 wt.% of ungrafted hydroxyapatite were used as the controls. The scaffolds were highly porous with evenly distributed and interconnected pore structures, and the porosity was around 90%. Besides the macropores of 100-300 mu m created by the leaching of NaCl particles, the micropores (1-50 mu m) in the pore walls increased with increasing content of op-HA in the composites of op-HA/PLGA. The op-HA particles could disperse more uniformly than those of pure HA in PLGA matrix. The 20 wt.% op-HA/PLGA sample exhibited the maximum mechanical strength, including bending strength (4.14 MPa) and compressive strength (2.31 MPa). The cell viability and the areas of the attached osteoblasts on the films of 10 wt.% op-HA/PLGA and 20 wt.% op-HA/PLGA were evidently higher than those on the other composites.

The Surface Modification of Hydroxyapatite Nanoparticles by the Ring Opening Polymerization of gamma-Benzyl-L-glutamate N-carboxyanhydride

The surface modification of hydroxyapatite (HA) nanoparticles by the ring opening polymerization (ROP) of gamma-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) was proposed to prepare the poly(gamma-benzyl-L-glutamate) (PBLG)-grafted HA nanoparticles (PBLG-g-HA) for the first time. HA nanoparticles were firstly treated by 3-aminopropylthriethoxysilane (APS) and then the terminal amino groups of the modified HA particles initiated the ROP of BLG-NCA to obtain PBLG-g-HA. The process was monitored by XPS and FT-IR. The surface grafting amounts of PBLG on HA ranging from 12.1 to 43.1% were characterized by thermal gravimetric analysis (TGA). The powder X-ray diffraction (XRD) analysis confirmed that the ROP only underwent on the surface of HA nanoparticles without changing its bulk properties. The SEM measurement showed that the PBLG-g-HA hybrid could form an interpenetrating net structure in the self-assembly process.

Multifunctional Hydroxyapatite Nanofibers and Microbelts as Drug Carriers

Luminescent, mesoporous, and bioactive europium-doped hydroxyapatite (HAp:Eu3+) nanofibers and microbelts have been prepared by a combination of sol-gel and electrospinning processes with a cationic surfactant as template. The obtained multifunctional hydroxyapatite nanofibers and microbelts, which have mesoporous structure and red luminescence, were tested as drug carriers by investigating their drug-storage/release properties with ibuprofen (IBU) as model drug. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution (HR) TEM, FTIR spectroscopy, N-2 adsorption/desorption, photoluminescence (PL) spectra, and UV/Vis spectroscopy were used to characterize the structural, morphological, textural, and optical properties of the resulting samples.

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.

Hydroxyapatite Nano- and Microcrystals with Multiform Morphologies: Controllable Synthesis and Luminescence Properties

Hydroxyapatite (Ca-5(PO4)(3)OH) nano- and microcrystals with multiform morphologies (separated nanowires, nanorods, microspheres, microflowers, and microsheets) have been successfully synthesized by a facile hydrothermal process. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra, kinetic decay, and electron paramagnetic resonance (EPR) were used to characterize the samples. The experimental results indicate that the obtained Ca-5(PO4)(3)OH samples show an intense and bright blue emission under long-wavelength UV light excitation. This blue emission might result from the CO2 center dot- radical impurities in the crystal lattice.

Synthesis and characterization of Eu-doped hydroxyapatite through a microwave assisted microemulsion process

Europium doped hydroxyapatite (Eu:HAp) nanosized particles with multiform morphologies have been successfully prepared via a simple microemulsion-mediated process assisted with microwave heating. The physicochemical properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra, and the kinetic decays, respectively. The results reveal that the obtained Eu:HAp particles are well assigned to the hexagonal lattice structure of the hydroxyapatite phase. Additionally, it is found that samples exhibit uniform morphologies which can be controlled by altering the pH values. Furthermore, the samples show the characteristic D-5(0)-F-7(1-4) emission lines of Eu3+ excited by UV radiation.