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Polymer matrix controlled release systems: Influence of polymer carrier and temperature on water uptake and protein release
Author(s) -
Sheppard Norman F.,
Madrid M. Yvette,
Langer Robert
Publication year - 1992
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1992.070460103
Subject(s) - polymer , differential scanning calorimetry , materials science , swelling , dynamic mechanical analysis , thermal diffusivity , chemical engineering , polymer chemistry , phase (matter) , composite material , chemistry , thermodynamics , organic chemistry , physics , engineering
The release of bovine serum albumin (BSA) from two types of ethylene‐co‐vinyl acetate (EVAc) polymer matrices was studied over the temperature range 4–50°C. Protein release and weight change of the matrices were evaluated in uitro . The copolymers were characterized using differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). During release, the devices initially exhibit a rapid increase in weight to a maximum, followed by a more gradual decrease for the duration of the release. The time to the maximum weight and the magnitude of the maximum weight gain are temperature dependent. These effects are related to the temperature‐dependent diffusivity of the BSA and elastic modulus of the EVAc. The DSC and TMA reveal melting of the crystalline phase of the polymer. The corresponding loss of mechanical integrity of the polymer leads to anomalous weight gains at these temperatures. The observed swelling and release is explained by a model in which the osmotic pressure of the protein within the pore network causes elastic deformation of the polymer matrix.