title: Physical characterization of thin semi-porous poly(L-lactic acid)/poly(ethylene glycol) membranes for tissue engineering.
abstract: This study examines physical properties of solvent-cast poly(L-lactic acid) (PLLA): poly(ethylene glycol) PEG membranes as a function of PEG molecular weight (MW) and incubation in vitro for 6 weeks. PEGs of MW 400, 1450 and 8000 were used. The morphological, thermal, mechanical and permeability properties of the membranes were studied prior to and after 3 and 6 weeks of incubation in phosphate-buffered saline (PBS) at 37 degrees C. The membranes showed a thickness of about 35+/-5 microm and were found to be semi-porous, with a non-porous surface as well as a porous surface with pore-diameters of 0.5-5 microm. The surface pore size was found to be a function of PEG MW used. All membranes were mechanically strong, with elastic moduli and tensile strength of 150-440 MPa and 7-36 MPa, respectively, all through the 6-week incubation period. The lower-MW PEGs plasticized PLLA based on high initial percent elongation; however, the effect was lost after 3 weeks of incubation in PBS. All membranes except those fabricated with PEG 8000 were impermeable for up to 6 weeks of incubation in PBS. Permeability studies showed that only PLLA:PEG 8000 membranes were permeable to methylene blue after 3 weeks of degradation.
authors.affiliation: Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 S 43rd Street, Box 80, Philadelphia, PA 19104, USA.
authors.forename: V
authors.initials: V
authors.lastname: Swaminathan
authors.forename: R
authors.initials: R
authors.lastname: Tchao
authors.forename: S
authors.initials: S
authors.lastname: Jonnalagadda
mesh_terms: D002152:Calorimetry, Differential Scanning; D019344:Lactic Acid / Q000737:chemistry*; D008566:Membranes / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D010539:Permeability; D011091:Polyesters; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D013314:Stress, Mechanical; D013499:Surface Properties; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; D011092:Polyethylene Glycols; C033616:poly(lactide)