Biodegradable poly[(amino acid ester)phosphazenes] for biomedical applications.

Polyphosphazene derivatives with amino acid ester side groups were prepared by reacting poly(dichlorophosphazene) with ethyl esters of amino acids and were characterized by1H,31P-NMR and DSC analyses. The in vitro rate of degradation of these polymers depended on the nature of the amino acids while introducing small amounts of depsipeptide ester co-substituents increased degradation rates. The rate of hydrolytic degradation of the poly[(organo)phosphazene] materials could be controlled by the amino acid ester by the depsipeptide ester side group content and by blending poly[(amino acid ester)phosphazenes] with poly[(amino acid ester)-co-(depsipeptide ester)phosphazenes]. Poly[(glycine ethyl ester)phosphazenes] prepared from poly[(dichloro)phosphazenes] degradation rates were independent of molecular weight. Degradations of polymer blends indicate that an intramolecular catalysis ofthe polymer by the pendent carboxylic acid.</jats:p

Compatibilization of co-plasticized cellulose acetate/water soluble polymers blends by reactive extrusion

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Biodegradable polyphosphazenes for drug delivery

Polyphosphazene derivatives having amino acid ester side groups were prepared by reaction of poly(dichlorophosphazene) with ethyl esters of amino acids. The in vitro degradation studies demonstrated that the rate of degradation depends on the nature of the amino acids. Introducing small amounts of hydrolytically sensitive groups such as depsipeptide ester or hydrolysis-catalysing moieties, such as histidine ethyl ester co-substituents, resulted in an increase of the degradation. The rate of hydrolytic degradation of the polyphosphazene material could be controlled by the content of the hydrolytically sensitive side groups or by blending hydrolysis-sensitive polymers with more stable derivatives. The results obtained from the in vivo implantation of biodegradable polyphosphazenes in mice indicate that the materials are very well tolerated by the animal body. Biodegradable polyphosphazenes have been used as matrix for the design of drug delivery systems. The rate of the in vitro release of mitomycin C from biodegradable polyphosphazenes can be controlled by changing the chemical composition of the polymer or by blending polymers of different chemical compositions