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Synthesis, Degradability, and Drug Releasing Properties of Methyl Esters of Fungal Poly( β , L ‐malic acid)
Author(s) -
PortillaArias José A.,
GarcíaAlvarez Montserrat,
de Ilarduya Antxon Martínez,
Holler Eggerhard,
Galbis Juan A.,
MuñozGuerra Sebastián
Publication year - 2008
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200700248
Subject(s) - chemistry , hydrolysis , malic acid , diazomethane , copolyester , polymer , solvent , thermal stability , copolymer , emulsion , polymer chemistry , nuclear chemistry , organic chemistry , citric acid , polyester
Methyl esters of microbial poly( β , L ‐malic acid) for conversion degrees of 25, 50, 75, and 100% were prepared by treatment of the polyacid with diazomethane. Esterification proceeded with retention of the molecular weight of the parent polyacid and the copolymers displayed a blocky microstructure consisting of short segments of malic and methyl malate sequences. The thermal stability of the copolyesters was lower than those of the parent homopolymers and all of them were fairly crystalline with melting temperatures within the range of 170–175 °C. They were degraded rapidly by water, the hydrolysis rate being highly dependent on the methylation degree. Microspheres with mean–average diameters in the range of 1–20 µm were prepared from the 100% methylated product by the emulsion–evaporation solvent method. Encapsulation of erythromycin was efficiently performed in these microparticles and its releasing upon incubation in simulated physiological medium was evaluated for different drug loads. Drug delivery was observed to occur by a releasing mechanism largely determined by the hydrodegradation of the host polymer and independent of the amount of loaded drug.