Dcm dmf

NFYs were produced by first electrospinning 10% w/v PCL (Mw ​= ​80 ​kDa, Sigma-Aldrich, St. Louis, MO, USA) dissolved in a 4:1 (v/v) mix of dichloromethane to N, N-dimethylformamide (DCM:DMF) (BDH Chemicals, Dawsonville, GA, USA), based on previous reports [33 (link)]. After the polymer solution was homogenous, it was loaded into a 10-cc syringe capped with a blunted 21-gauge needle. The polymer solution was electrospun under ambient conditions (21.6 ​°C; relative humidity (RH) ​= ​45%) with an applied voltage of 18.0 ​kV and a flow rate of 0.8 ​ml/h. During electrospinning, nanofibers were collected on a high-speed rotating drum (7 ​mm in diameter). After 1 ​ml of the polymer solution was collected on the drum, the fiber mat was cut into 3–15 ​mm strips and rolled along the drum to form the NFYs. Using a razor blade, the yarn was cut and removed from the drum.

Continuous PCL fibers were prepared with phase-separation wet spinning as previously reported [12 (link)]. First, 20% w/v PCL (Mw ​= ​80 ​kDa, Sigma-Aldrich, St. Louis, MO, USA) and 0.5% w/v F-127 (Sigma-Aldrich, St. Louis, MO, USA) were dissolved in a 4:1 (v/v) mix dichloromethane to N, N-dimethylformamide (DCM: DMF) (BDH Chemicals, Dawsonville, GA, USA) and stirred until a homogeneous solution with uniform viscosity was achieved. Next, a 10-cc syringe capped with a 21-gauge needle was loaded with the polymer solution and extruded under ambient conditions (21.6 ​°C; RH ​= ​45%) with a coagulation bath of 70% EtOH at a rate of 0.3 ​ml/h. Fibers were collected on a rotating drum with take-up rates ranging from 5 to 25 RPM. After fibers were collected, they were removed with a razor blade and allowed to air dry. Similarly, PGLA (90:10) (Mw ​= ​60 ​kDa, DURECT Corporation, Pelham AL, USA) fibers were produced by creating 25% (w/v) PGLA solution dissolved in a 4:1 (v/v) mix of DCM: DMF and extruded under the same conditions as the PCL fibers. In the case of direct extrusion into an NaCl bath, NaCl (0.65 ​g NaCl/kg ethanol) was added to the bath and the above process was carried out as described.