title: Nitroxyl radical incorporated electrospun biodegradable poly(ester Amide) nanofiber membranes.
abstract: Biodegradable amino-acid-based poly(ester amide) (PEA) ultra-fine fibers pre-loaded with a nitroxyl radical model compound, 4-amino-2.2.6.6-tetramethylpiperidine-1-oxy (4-amino-TEMPO), were prepared by electrospinning. The fiber size and morphology were shown to be greatly affected by the composition ratio of the solvent mixture (chloroform to DMF) prepared for electrospinning. Nano-size PEA fibers (approx. 640 nm) were obtained when PEA dope was electrospun from the chloroform/DMF solvent mixture at a volume ratio of 2 to 1 vs. 3.5 mum size PEA fibers obtained from chloroform-based electrospun dope. Due to the low glass transition temperature and completely amorphous structures, the PEA electrospun fibrous membranes gradually lost their fiber characteristic during 1 month incubation in PBS buffer at 37 degrees C. The glass transition temperature and heat of fusion of PEA electrospun fibers increased with an increasing incubation time and the most significant change occurred in the first day of incubation in PBS. A sustained release of 4-amino-TEMPO from the electrospun PEA nanofiber membranes was observed over the 1-month incubation period in PBS buffer at 37 degrees C and 38% of the incorporated 4-amino-TEMPO (initial loading level 10 mg/g PEA fibers) was released in one month. During this 1 month incubation in PBS buffer, there were only 1.2% weight loss and 11.7% molecular weight reduction for the electrospun PEA fibrous membranes. In an alpha-chymotrypsin medium (0.1 mg/ml PBS), however, the same electrospun PEA fibrous membranes showed more than 80% weight loss within 6 days and a complete release of encapsulated 4-amino-TEMPO within 5 days.
authors.affiliation: Fiber and Polymer Science Program, Department of Fiber Science and Apparel Design, Cornell University, Ithaca, NY 14853-4401, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: Chih-Chang
authors.initials: CC
authors.lastname: Chu
mesh_terms: D000577:Amides / Q000737:chemistry*; D001671:Biochemistry / Q000379:methods; D001672:Biocompatible Materials / Q000737:chemistry*; D002725:Chloroform / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000494:pharmacology; D016503:Drug Delivery Systems; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry; D009589:Nitrogen Oxides / Q000494:pharmacology*; D009757:Nylons / Q000737:chemistry*; D011091:Polyesters / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013696:Temperature
chemical_list: D000577:Amides; D001672:Biocompatible Materials; D003497:Cyclic N-Oxides; D005609:Free Radicals; D009589:Nitrogen Oxides; D009757:Nylons; D011091:Polyesters; D012997:Solvents; C015527:4-amino-TEMPO; D009569:Nitric Oxide; D002725:Chloroform; C039900:nitroxyl