title: Nanoscale mechanical measurement determination of the glass transition temperature of poly(lactic acid)/everolimus coated stents in air and dissolution media.
abstract: Localized atomic force microscopy (AFM) force analysis on poly(lactic acid) (PLA) and poly(lactic acid)/everolimus coated stents has been performed under ambient conditions. Similar Young's modulus were derived from both PLA and PLA/everolimus stent surface, namely 2.25+/-0.46 and 2.04+/-0.39GPa, respectively, indicating that the drug, everolimus does not significantly effect the mechanical properties of PLA up to a 1:1 (w/w) drug loading. Temperature controlled force measurements on PLA only coated stents in air and in a 1% Triton surfactant solution allowed the glass transition temperature (T(g)) of the polymer to be determined. A significant drop of the Young's modulus in solution was observed at 36 degrees C, suggests that in vivo the T(g) of the polymer is below body temperature. The possible consequences on drug release and the mechanisms by which this may occur are considered.
authors.affiliation: Laboratory of Biophysics and Surface Analysis, School of Pharmacy, The University of Nottingham, Nottingham NG7 2RD, UK.
authors.forename: Ming
authors.initials: M
authors.lastname: Wu
authors.forename: Lothar
authors.initials: L
authors.lastname: Kleiner
authors.forename: Fuh-Wei
authors.initials: FW
authors.lastname: Tang
authors.forename: Syed
authors.initials: S
authors.lastname: Hossainy
authors.forename: Martyn C
authors.initials: MC
authors.lastname: Davies
authors.forename: Clive J
authors.initials: CJ
authors.lastname: Roberts
mesh_terms: D000068338:Everolimus; D005898:Glass; D006358:Hot Temperature; D019344:Lactic Acid / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D020123:Sirolimus / Q000031:analogs & derivatives* / Q000737:chemistry; D012995:Solubility; D015607:Stents
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D000068338:Everolimus; D020123:Sirolimus