Fabrication of Collagen-PLLA Nanofibers

Acid soluble collagen type I (Coll), obtained from bovine skin (Kensey Nash Corporation DSM Biomedical, Exton, USA) and poly-L (lactic) acid (PLLA) (Lacea H.100-E, Mw = 8.4 × 10⁴ g mol⁻¹, PDI = 1.7, Mitsui Fine Chemicals, Dusseldorf, Germany) were used. As a solvent system, a mixture of 2,2,2-trifluoroethanol (TFE), 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) (Sigma-Aldrich, Staint Louis, USA) were used in a 50:50 (v/v) percentage. To crosslink Coll in the nanofibers, N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) and ethanol (Sigma-Aldrich, Staint Louis, USA) were used. The following polymeric blend solution was used: PLLA/Coll-75/25 (w/w) prepared from a 18% (w/v) solution of PLLA and Coll dissolved in TFE:HFIP = 50:50 (v/v).