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Tehrān, Iran

In this investigation a new series of biodegradable pH-responsive hydrogel microspheres were prepared, characterized and in-vitro evaluated as potential carriers for oral delivery of protein drugs. The microspheres are based on ionotropically-crosslinked mixture of sodium alginate and chemically modified carboxymethyl chitosan and coated through polyelectrolyte complexation with chitosan grafted with poly(ethylene glycol). The main objective of the developed microspheres is to survive the harsh acidity of stomach and preferably release peptide and protein drugs in intestine. Both ionotropic gelation and coating process were carried out under mild aqueous conditions, which should be appropriate for retention of biological activity of protein drugs. Swelling studies were carried out for the microspheres at 37 °C in simulated gastric and intestinal fluids. Morphology, size and in-vitro biodegradation of the microspheres were also investigated. A model protein drug was entrapped and the in-vitro drug release profiles were established. The preliminary investigation of the microspheres developed in this study showed a consistent swelling pattern, high entrapment efficiency and promising sustained release profiles of the model protein drug. © 2010 Elsevier Ltd. All rights reserved. Source

Ganjali M.R.,University of Tehran | Motakef-Kazami N.,University of Tehran | Faridbod F.,University of Tehran | Khoee S.,Polymer Laboratory | Norouzi P.,University of Tehran
Journal of Hazardous Materials

A novel carbon paste ion selective electrode for determination of trace amount of lead was prepared. Multi-walled carbon nanotubes (MWCNTs) and nanosilica were used for improvement of a lead carbon paste sensor response. MWCNTs have a good conductivity which helps the transduction of the signal in carbon paste electrode. The electrode composition of 20 wt% paraffin oil, 57% graphite powder, 15% ionophore (thiram), 5% MWCNTs, and 3% nanosilica showed the stable potential response to Pb2+ ions with the Nernstian slope of 29.8 (±0.2) mV decade-1 over a wide linear concentration range of 10-7-10-2 mol L-1. The electrode has fast response time, and long term stability (more than 2 months). The proposed electrode was used to determine the concentration of lead ions in waste water and black tea samples. © 2009 Elsevier B.V. All rights reserved. Source

Ashjari M.,Iran Polymer And Petrochemical Institute | Khoee S.,Polymer Laboratory | Mahdavian A.R.,Iran Polymer And Petrochemical Institute | Rahmatolahzadeh R.,Polymer Laboratory
Journal of Materials Science: Materials in Medicine

Self-assembled nanomicelles can be used as synthetic biomaterials and colloidal carriers for poorly water-soluble drug delivery systems. Some of these micellar systems have been introduced in clinical trials and showed hopeful results relating to their therapeutic index in patients. Biodegradable nanomicelle was prepared from self-assembling amphiphilic block copolymer composed of poly (DL-lactic-co-glycolic acid) (PLGA) as a core and polyethylene glycol (PEG) as a corona. The PLGA-PEG block copolymer was first synthesized and characterized by FTIR, 1H NMR, GPC and inherent viscosity measurements. The nanomicelle formed by PLGA-PEG block copolymer in the aqueous solution was characterized by dynamic light scattering, zeta potential, scanning electron microscopy (SEM) and fluorescence excitation and emission spectra of pyrene probe. The critical micelle concentration of obtained nanomicelle was about 0.006 mg/mL, with the size of about 160 nm and the zeta potential of -29 mV. Insulin-loaded PLGA-PEG nanomicelles were prepared by modified dialysis method and the physicochemical parameters of the micelles such as drug content, entrapment efficiency and in vitro drug release were characterized. The results showed that insulin was entrapped into PLGA-PEG nanomicelles with drug loading of 3.9 wt% and entrapment efficiency of 55 wt%. The nanomicelles containing insulin exhibited a controlled release profile. These observations suggested that the PLGA-PEG block copolymers nanomicelles have been prepared by a new synthetic route are potent nanocarrier for poorly water-soluble drugs as insulin. © Springer Science+Business Media, LLC 2012. Source

El-Sherbiny I.M.,Polymer Laboratory | El-Sherbiny I.M.,University of Texas at Austin | Smyth H.D.C.,University of Texas at Austin
Carbohydrate Polymers

In the present study, carboxymethyl chitosan was prepared and characterized. Photo-induced graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) onto carboxymethyl chitosan (CMCs) was then carried out under nitrogen atmosphere in aqueous solution using 2,2-dimethoxy-2-phenyl acetophenone (PI) as photo-initiator. Grafting process was confirmed and the produced copolymers were characterized with aid of elemental analysis, FTIR, 2D-X ray diffraction, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The effects of HEMA and PI concentrations and the reaction time on the grafting yield were investigated by determining the grafting percentage and grafting efficiency. Under the applied experimental conditions, the optimum grafting conditions were obtained at: CMCs = 0.2 g, HEMA = 0.615 mol/L, PI = 0.0078 mol/L and reaction time = 90 min. The synthesized copolymers revealed a self-ability to form physically crosslinked hydrogels. The hydrogel nature of the copolymers was investigated by studying the solubility profiles and the cyclic swelling-deswelling behavior of copolymers with different grafting extents. These investigations of the photo-synthesized graft copolymers showed that they can be tailored and exploited as promising carriers for drug delivery purposes. © 2010 Elsevier Ltd. Source

Lee J.S.,Polymer Laboratory | Cho K.C.,Polymer Laboratory | Ku K.H.,Polymer Laboratory | Clio G.,Polymer Laboratory | Lee J.-H.,Hoseo University
Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012

The conventional XLPE has superior thermal and mechanical properties clue to chemical cross-linking. In spite of these advantages, this material can damage on our environment because it is not recyclable. On the other hand, the new-PE we've developed recently doesn't have chemical cross-linking point therefore this new material can be recyclable. In this article, we mainly focus on introducing the advantages of our new PE material to you by explaining its structure and mechanical & electrical properties. We will confirm that the effect of additives on AC Breakdown and conductive current density. Also, we will add LDPE to make up for processa bili ty and then check the effect of LDPE on electrical properties as well. © 2012 IEEE. Source

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