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Enhanced Solubility (enhanced + solubility)
Selected AbstractsEnhanced solubility and dissolution rate of lamotrigine by inclusion complexation and solid dispersion techniqueJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2008Vikram R. Shinde ABSTRACT The solid-state properties and dissolution behaviour of lamotrigine in its inclusion complex with ,-cyclodextrin (,CD) and solid dispersions with polyvinylpyrrolidone K30 (PVP K30) and polyethyl-eneglycol 6000 were investigated. The phase solubility profile of lamotrigine with ,CD was classified as AL -type, indicating formation of a 1:1 stoichiometry inclusion complex, with a stability constant of 369.96 ± 2.26 M,1. Solvent evaporation and kneading methods were used to prepare solid dispersions and inclusion complexes, respectively. The interaction of lamotrigine with these hydrophilic carriers was evaluated by powder X-ray diffractometry, Fourier transform infrared spectroscopy and differential scanning calorimetry. These studies revealed that the drug was no longer present in crystalline state but was converted to an amorphous form. Among the binary systems tested, PVP K30 (1:5) showed greatest enhancement of the solubility and dissolution of lamotrigine. [source] Fabrication and characterization of solution cast MWNTs/PEI nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Lu Shao Abstract Under mild conditions with the aid of ultrasonic, multi-walled carbon nanotubes (MWNTs) have been functionalized by mixed acid treatment which was proved by FTIR and XPS. According to SEM, acid treatment on MWNTs decreased the thickness of the membrane. However, no devastating damage and fracture happened on MWNTs after acid treatment under mild conditions. Precipitation observation illustrated that the enhanced solubility of MWNTs in water, ethanol, and dimethylformaide (DMF). Further, MWNTs/polyetherimide (PEI) nanocomposite films have been prepared by the simple solution casting method. The dispersion of MWNTs in polyetherimide (PEI) matrix was observed by Atomic Force Microscopy (AFM) which illustrated the improved dispersion for acid treated MWNTs in PEI. The adding of MWNTs in PEI decreased the dispersive component of surface energy and increased the polar component of surface energy, which resulted in the decrement of film surface energy. Differential scanning calorimetry showed that the glass transition temperature of PEI increased by about 4°C after the introduction of MWNTs. This improvement was related to the better affinity between MWNTs and PEI matrix, which also resulted in the improvement of mechanical strength in MWNTs/PEI nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Preparation of monomethyl poly(ethylene glycol)- g -chitosan copolymers with various degrees of substitution: Their ability to encapsulate and condense plasmid DNAJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Wei Zhang Abstract Chitosan (CS) has great potential as a nonvirus gene delivery vector, but its application is limited because of poor water solubility. Monomethyl poly(ethylene glycol) (mPEG)- graft -CS copolymers were synthesized by the reaction of mPEG,aldehyde (oxidized mPEG) with amino groups on CS chains; they showed enhanced solubility in water. Copolymers with various mPEG degrees of substitution (DS) and CS molecular weights were obtained, and their capabilities of DNA encapsulation were compared through gel retardation assay and particle size and , potential measurements. The effects of different ratios of primary amines on CS to the phosphate groups on DNA (N/P ratios), DS, and molecular weights on particle size and encapsulation efficiency were investigated. The results show that high N/P ratios and proper DS were necessary for the formation of well-distributed complex particles. Among all of these samples, mPEG (3.55),CS (50 kDa)/DNA complexes [where the parentheses following mPEG indicate DS (%), and the parentheses following CS indicate the molecular weight of CS] raised the , potential from negative to positive most quickly, yielded the smallest particle size, and were retarded in agarose gel at the lowest N/P ratio; this indicated the best efficiency of DNA encapsulation. On the contrary, mPEG (0.80),CS (50 kDa)/DNA complexes raised the , potential to positive most slowly, fluctuated around the value 0 from N/P ratios of 15 : 1 to 30 : 1, and were retarded in agarose gel at the highest N/P ratio; this indicated the lowest efficiency of encapsulating plasmids. Copolymers with desirable efficiencies of DNA encapsulation could be promising gene carriers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Low loss second-order non-linear optical crosslinked polymers based on a phosphorus-containing maleimidePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2004Chih-Ping Chen Abstract A series of crossslinked organic and organic/inorganic polymers based on maleimide chemistry have been investigated for second-order non-linear optical (NLO) materials with excellent thermal stability and low optical loss. Two reactive chromophores (maleimide-containing azobenzene dye and alkoxysilane-containing azobenzene dye) were incorporated into a phosphorus-containing maleimide polymer, respectively. The selection of the phosphorus-containing maleimide polymer as the polymeric matrices provides enhanced solubility and thermal stability, and excellent optical quality. Moreover, a full interpenetrating network (IPN) was formed through simultaneous addition reaction of the phosphorus-containing maleimide, and sol-gel process of alkoxysilane dye (ASD). Atomic force microscopy (AFM) results indicate that the inorganic networks are distributed uniformly throughout the polymer matrices on a nano-scale. The silica particle sizes are well under 100,nm. Using in situ contact poling, the r33 coefficients of 2.2,17.0,pm/V have been obtained for the optically clear phosphorus-containing NLO materials. Excellent temporal stability (100°C) and low optical loss (0.99,1.71,dB/cm; 830,nm) were also obtained for these phosphorus-containing materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Camouflaged Carborarods Derived from B -Permethyl-1,12-diethynyl- para - and B -Octamethyl-1,7-diethylnyl- meta -carborane ModulesCHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2005Axel Herzog Dr. Abstract Rigid camouflaged carborarods constructed from the corresponding C,C,-diethynyl derivatives of B -decamethyl-1,12-dicarbadodecaborane(12) (6) and B -octamethyl-1,7-dicarbadodecaborane(12) (48) have been synthesized by largely conventional organic transformations. These carborarods are the longest discrete rod species available by this method in which B-methylated p -carborane and m- carborane cages are linked through their carbon vertices by using butadiynylene moieties. They exhibit enhanced solubility in common organic solvents relative to all other presently known carborane-based rigid-rod molecules. The oxidative coupling of bis(ethynyl) derivatives of 6 generates oligomers containing, on average, 16 carborane modules. The structural characterization of the corresponding dimeric species revealed that the carborarods possess a sinusoidal chain distortion in the solid state. The stereoelectronic properties of these and related model carborarods were evaluated by using molecular dimensions as a monitor for the comparison of computational and experimental methods. In addition, the effect of exhaustive B-methylation of 12- and 10-vertex para -carborane cages in a series of model C,C,-diethynyl derivatives was similarly investigated by computational and structural studies. As expected, a correlation of intercage CC bond lengths with cage size was observed and was attributed to hybridization effects. B-Permethylation had no significant structural effect with either 10- or 12-vertex cage derivatives. Relative to unsubstituted compounds, thermal and chemical stabilities of B-permethylated derivatives were increased through the operation of a steric "bumper-car" process, and solubilities in organic solvents were enhanced. The formation of linear, sterically encumbered platina,carborarods using ethynyl derivatives of 6 as precursors is described. [source] | ||||||||||