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Chih-chang Chu - One of the best experts on this subject based on the ideXlab platform.
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water insoluble cationic poly ester amide s synthesis characterization and applications
Journal of Materials Chemistry B, 2013Co-Authors: Chih-chang ChuAbstract:We reported a new family of water insoluble, biocompatible and biodegradable cationic arginine and phenylalanine based poly(ester amide)s (Arg-Phe-Peas) for potential biomedical applications. The Arg-Phe-PEA consists of 3 building blocks: amino acids, diols, and dicarboxylic acids and was prepared from both L-arginine and L-phenylalanine amino acids by solution polycondensation. The structure and properties of Arg-Phe-Peas were characterized by standard physicochemical methods. In vitro biological tests of the Arg-Phe-Peas included enzymatic biodegradation, cell attachment and proliferation, and macrophage inflammation tests. The enzymatic biodegradation tests showed that the biodegradation rate of Arg-Phe-Peas can be controlled by regulating the polymer composition (the ratio of Arg to Phe). The cellular tests indicated that the bovine aortic endothelial cells (BAECs) have very good cell attachment and proliferation on the Arg-Phe-PEA surface. The in vitro inflammation data showed that the Arg-Phe-Peas induced far lower inflammatory response than FDA approved biomaterials. By a nano-precipitation method, Arg-Phe-Peas were formulated into nanoparticles (NPs) with particle sizes below 200 nm. The protein release profiles from Arg-Phe-PEA NPs showed that the introduction of arginine significantly enhanced the protein encapsulation efficacy and changed the protein release rate compared with pure phenylalanine based poly(ester amide)s (Phe-Peas).
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synthesis and characterization of a new family of cationic amino acid based poly ester amide s and their biological properties
Journal of Applied Polymer Science, 2012Co-Authors: H Song, Chih-chang ChuAbstract:A new family of positively charged and water soluble amino acid-based poly(ester amide)s (Peas) consisting of nontoxic L-arginine, diols, and aliphatic dicarboxylic acids building blocks was synthesized and characterized. The L-arginine based Peas (Arg-Peas) were prepared by a solution polycondensation of two monomers: tetra-p-toluenesulfonic acids salts or hydrochloride acid salts of bis-(L-arginine) α, ω-alkylene diesters (monomer II), and di-p-nitrophenyl esters of saturated or unsaturated dicarboxylic acids (monomer I). Optimal reaction conditions were studied as functions of type of solvents and acid acceptors, concentrations of reactants. The molecular weights (Mn and Mw) of Arg-Peas measured by GPC ranged from 20,000 to 60,000 g mol−1 with a rather narrow molecular weight distribution below 1.5. The chemical structures were confirmed by IR and NMR spectra. Arg-Peas obtained were all amorphous materials with Tg from 33 to 125°C, depending on the number and the type (saturated vs. unsaturated) of methylene groups in diols or diacids, and the type of counter-ions attached to the guanidine group of the Arg-based Peas. The Arg-Peas had a high solubility in all polar solvents, including water. Preliminary studies of cell morphology and DNA capture capability of Arg-Peas indicated that this new family of cationic Peas was nontoxic and more biocompatible than a commercial transfection agent (Superfect®), and can successfully capture plasma DNA. The strong positive charge of Arg-Peas as well as their good water solubility could provide unique characteristics for potential gene transfection or other charge preferred biomedical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
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Synthesis and characterization of ionic charged water soluble arginine-based poly(ester amide)
Journal of Materials Science: Materials in Medicine, 2011Co-Authors: Martha A. Mutschler, Chih-chang ChuAbstract:A family of water soluble and positively charged l -arginine based poly(ester amide)s (Arg-Peas) was synthesized and characterized. These biodegradable polymers consist of three nontoxic building blocks: l -arginine, diols, and dicarboxylic acids. The Arg-Peas were prepared by solution polycondensation reaction of tetra- p -toluenesulfonic acids salts of bis-( l -arginine) α, ω-alkylene diesters and di- p -nitrophenyl esters of dicarboxylic acids. Optimal conditions of the monomers and polymers synthesis were investigated, and the monomers and Arg-Peas were chemically characterized. Arg-Peas were found to have good solubility in water and many other polar solvents. Structure–function relationship of the Arg-Peas revealed that changing the number of methylene groups in the diol or/and diacid segment could finely tune the hydrophobic and cationic properties of the Arg-Peas. MTT assay showed that all the prepared Arg-Peas were non-toxic to the cell lines even at very large doses. Arg-Peas with double bond functionality could be photo-crosslinked with polyethylene glycol diacrylate to form cationic hybrid hydrogels.
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biodegradable arginine based poly ester amide s as non viral gene delivery reagents
Biomaterials, 2008Co-Authors: Dai Yamanouchi, Chih-chang Chu, Andrew N Lazar, Craig K Kent, Bo LiuAbstract:A novel family of synthetic biodegradable poly(ester-amide)s (Arg-Peas) was evaluated for their biosafety and capability to transfect rat vascular smooth muscle cells, a major cell type participating in vascular diseases. Arg-Peas showed high binding capacity toward plasmid DNA, and the binding activity was inversely correlated to the number of methylene groups in the diol segment of Arg-Peas. All Arg-Peas transfected smooth muscle cells with an efficiency that was comparable to the commercial transfection reagent Superfect®. However, unlike Superfect®, Arg-Peas, over a wide range of dosages, had minimal adverse effects on cell morphology, viability or apoptosis. Using rhodamine-labeled plasmid DNA, we demonstrated that Arg-Peas were able to deliver DNA into nearly 100% of cells under optimal polymer-to-DNA weight ratios, and that such a high level of delivery was achieved through an active endocytosis mechanism. A large portion of DNA delivered, however, was trapped in acidic endocytotic compartments, and subsequently was not expressed. These results suggest that with further modification to enhance their endosome escape, Arg-Peas can be attractive candidates for non-viral gene carriers owning to their high cellular uptake nature and reliable cellular biocompatibility.
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in vitro enzymatic biodegradation of amino acid based poly ester amide s biomaterials
Journal of Materials Science: Materials in Medicine, 2004Co-Authors: George Tsitlanadze, T Kviria, Ramaz Katsarava, Chih-chang ChuAbstract:A systematic in vitro biodegradation study of regular poly(ester amide)s (Peas) composed of naturally occurring hydrophobic alpha-amino acids, fatty diols and dicarboxylic acids was carried out in the presence of hydrolases like trypsin, alpha-chymotrypsin, and lipase. An automatic potentiometric titration method was used to examine the biodegradation property of the Peas. Spontaneous immobilization (absorption) of the enzymes onto the Peas films surfaces was observed. The surface immobilized enzyme not only accelerated the erosion of the Peas but also was able to catalyze the hydrolysis of both low-molecular-weight (ATEE) and high-molecular-weight (protein) external substrates. It was found that the enzyme surface absorption process is reversible by nature. A kinetic method for a quantitative determination of the enzyme desorbed from the film surface was developed. The enzymes could also be impregnated into the Peas to make them "self-destructive" at a target rate. A comparison of the Peas' in vitro biodegradation data with polylactide (PDLLA) showed that Peas exhibited a far more tendency toward enzyme catalyzed biodegradation than PDLLA.
H.b. Cannon - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Various Canning Crop Rotations On Certain Soil Constituents Over a Five-Year Period1
Canadian Journal of Agricultural Science, 2016Co-Authors: H. Hill, R.f. Bishop, H.b. CannonAbstract:Changes that have occurred in certain soil constituents during the initial 5-year period in nine different rotations with canning Peas, tomatoes and corn are discussed In a 2-year rotation of Peas and tomatoes or Peas and corn, where in addition to commercial fertilizer twelve tons of manure were applied every second year and two green manure crops were grown after harvesting the Peas, an increase occurred in soil organic matter, exchangeable potassium and easily acid soluble plus adsorbed phosphorus Results from another rotation where the corn stover was returned to the soil indicate this practice to be helpful in maintaining soil organic matter. The highest yields of corn, Peas and tomatoes occurred where manure was used and the highest average yields were obtained in 2-year rotations with uninterrupted production of canning crops. Reduced yields of Peas and corn occurred when clover was seeded with these crops. Soil test values as well as the calculated additions and removals of phosphorus and potassiu...
John C. Mathers - One of the best experts on this subject based on the ideXlab platform.
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digestion by pigs of non starch polysaccharides in wheat and raw Peas pisum sativum fed in mixed diets
British Journal of Nutrition, 1991Co-Authors: J S Goodlad, John C. MathersAbstract:: The digestion by pigs of non-starch polysaccharides (NSP) in wheat and raw Peas (Pisum sativum) fed in mixed diets was measured. In the four experimental diets, wheat was included at a constant 500 g/kg whilst Peas contributed 0-300 g/kg and these were the only dietary sources of NSP. Separate estimates of digestibility for wheat and Peas were obtained by using a multiple linear regression technique which also tested the possibility that the presence of Peas might influence the digestibility of wheat NSP. There was little evidence of the latter and it was found that the digestibility of Peas NSP (0.84) was considerably greater than that of wheat (0.65). The non-cellulosic polysaccharides (NCP) had twofold greater digestibilities than had cellulose for both foods with essentially all the Peas NCP being digested. Faecal alpha, epsilon-diaminopimelic acid concentration increased with feeding of Peas, suggesting stimulation of bacterial biomass production in the large intestine using the readily fermented Peas NSP. All three major volatile fatty acids produced by large intestinal fermentation were detected in jugular blood and increased significantly with increasing Peas inclusion rate in the diet.
Lixia Zhang - One of the best experts on this subject based on the ideXlab platform.
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Peas a robust energy conserving protocol for long lived sensor networks
International Conference on Distributed Computing Systems, 2003Co-Authors: Gary Zhong, Jerry Cheng, Lixia ZhangAbstract:In this paper we present Peas, a robust energy-conserving protocol that can build long-lived, resilient sensor networks using a very large number of small sensors with short battery lifetime. Peas extends the network lifetime by maintaining a necessary set of working nodes and turning off redundant ones. Peas operations are based on individual node's observation of the local environment and do not require any node to maintain per neighbor node state. Peas performance possesses a high degree of robustness in the presence of both node power depletions and unexpected failures. Our simulations and analysis show that Peas can maintain an adequate working node density in the face of up to 38% node failures, and it can maintain roughly a constant overhead level under various deployment conditions ranging from sparse to very dense node deployment by using less than 1% of total energy consumption. As a result, Peas can extend a sensor network's functioning time in linear proportion to the deployed sensor population.
Peter A. Sopade - One of the best experts on this subject based on the ideXlab platform.
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dependence of in vitro starch and protein digestions on particle size of field Peas pisum sativum l
Lwt - Food Science and Technology, 2015Co-Authors: G T Nguyen, Michael J. Gidley, Peter A. SopadeAbstract:Two varieties (Maki and Walana) of field Peas were hammer- and disc-milled to various particle size distributions. Water hydration characteristics were significantly (p<0.05) dependent on the particle size distribution of the milled Peas, and were adequately described by a multiple regression equation. In-vitro starch (from glucose release) and protein digestions (from pH changes) of the milled Peas were modelled using a modified first order kinetic equation and related to the particle sizes. The hammer-milled Peas digested the most, possibly because of mechanical and frictional effects of the mill. The rate of protein digestion of the hammer-milled Peas was independent (p<0.05) of the particle size, while the reciprocal of the rate of protein digestion of the disc-milled Peas was significantly (p<0.05) dependent on the square of the particle size. The rate of starch digestion of the disc-milled Peas was independent (p<0.05) of the particle size, but the reciprocal of the rate of starch digestion of the hammer-milled Peas was significantly (p<0.05) dependent on the square of the particle size. The in-vitro protein digestion, based on pH changes, proceeded at a much faster rate than the in-vitro starch digestion in the milled Peas. This has implications for nutrient asynchrony, which is discussed.