Surface Characteristics Of Microspheres Research Articles

High-capacity anion exchangers based on poly (glycidylmethacrylate-divinylbenzene) microspheres for ion chromatography

Poly (glycidylmethacrylate-divinylbenzene) microspheres were prepared by the two-staged swelling and polymerization method and applied to prepare anion exchange stationary phases. Methylamine, dimethylamine, trimethylamine, diethylamine and triethylamine were selected to prepare the quaternary ammonium groups of anion exchangers, respectively. The diameters and surface characteristics of microspheres were measured by scanning electron microscope and nitrogen adsorption-desorption measurements. The anion exchangers were characterized by Fourier transform infrared spectrum, elemental analysis and breakthrough curve methods. The chromatographic performances of anion exchangers were illustrated by separating conventional anions, organic weak acids and carbohydrates. The results indicated that the anion exchange capacities were controllable by changing either the content of glycidylmethacrylate in microspheres or the number of bonded quaternary ammonium layer. Meanwhile, the substituents of quaternary ammonium groups greatly influenced the separation properties of anion exchangers. Finally, the three-layer methylamine-quaternized anion exchanger was successfully applied for the determination of fluoride in tea sample. The content of fluoride was detected to be 0.13mgg−1 without the interference of acetate and formate.

Preparation and Determination of Drug-Polymer Interaction and In-vitro Release of Mefenamic Acid Microspheres Made of CelluloseAcetate Phthalate and/or Ethylcellulose Polymers.

The objective of this study was to formulate and evaluate the drug-polymer interaction of mefenamic acid (MA) using two polymers with different characteristics as ethylcellulose (EC) and/or cellulose acetate phthalate (CAP). Microspheres were prepared by the modified emulsion solvent evaporation (MESE). The effect of drug-polymer interaction was studied for each of microspheres. Important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteristics of microspheres, scanning electronic microscopy (SEM), powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC). The in-vitro release studies are performed in Tris buffer (pH 9) with Sodium lauryl sulfate (SLS). Microspheres containing CAP and EC showed 68-97% and 63-76% of entrapment efficiency, respectively. The thermogram X-ray and DSC showed stable character of MA in the microspheres and revealed an absence of drug polymer interaction. The prepared microspheres were spherical in shape and had a size range of 235-436 μm for CAP-microspheres and 358-442 μm for EC-microspheres. The results suggest that MA was successfully and efficiently encapsulated; the release rates of matrix microspheres are related to the type of polymer, only when polymers (EC and CAP combine with 1 : 1 ratio) were used to get prolonged drug release with reducing the polymers content in the microspheres. Data obtained from in-vitro release for microspheres and commercial capsule were fitted to various kinetic models and the high correlation was obtained in the peppas model. Mefenamic acid, Ethylcellulose, Cellulose acetate phthalate, Microparticles, Modified emulsion-solvent evaporation.

合成高分子表面へのタンパク質の吸着

In this article I have reviewed (blood) proteins adsorption onto synthetic polymer surfaces, i. e., onto polymeric microspheres. First, the surface characteristics of polymeric microspheres (polymer latices) were examined. As a result, hydrogel polymer layers, e. g., poly (acrylamide) (poly-AAm) and poly (2-hydroxyethyl methacrylate) (poly-HEMA) layers were found to exist on the microsphere surfaces of styrene (St) /AAm and St/HEMA copolymers (P (St/AAm) and P (St/HEMA)), respectively. Subsequently, singular and competitive protein adsorption onto polymeric microspheres was investigated as a function of pH and ionic strength, surface characteristics of microspheres, coexistent electrolyte ions. Each protein showed the maximum adsorption near its isoelectric point. The amounts adsorbed onto hydrophilic P (St/AAm) and P (St/HEMA) microspheres were much smaller than that onto hydrophobic polystyrene (PS) microsphere, particularly in the neutral and alkaline pH regions. Fibrinogen adsorbed preferentially from the protein mixture of albumin, γ-globulin, and fibrinogen. Further, the adsorbability of heat-denatured albumin was studied. Compared with the native component of the protein, the denatured components adsorbed preferentially onto microspheres.

Bioadhesive polymer-grafted starch microspheres bearing isosorbide dinitrate for buccal administration.

A polymer-grafted mucoadhesive system bearing isosorbide dinitrate was prepared for buccal administration. Polymer grafting of starch microspheres modified drug release and surface characteristics of microspheres. Bioadhesion and factors affecting bioadhesion were studied. Process variables that could affect microsphere size, and as a result the release of the drug, were also studied. It was observed that compression of grafted starch microspheres modified drug release and extended drug action via slow release following buccal application. Prepared system(s) were characterized for drug release and in vivo performance and compared with conventional oral treatment. The systems were noted to be promising.