Tecoflex sg 80a

Medical-grade soft TPU pellets, Tecoflex® SG-80A (Lubrizol), were blended with dry fibroin foam at weight ratios of 2:1, 1:1, and 1:2, and dissolved in hexafluoroisopropanol (HFIP, CovaChem) at 12 w/v%. A TPU solution was also prepared at 10 w/v% by dissolving the pellets in a mixed solvent of chloroform and dimethylformamide (CF/DMF = 3/1 v/v, Sigma- Aldrich). All of the mixtures were stirred at room temperature for 12 hours before electrospinning. The conductivities of the TPU/fibroin solutions were measured by a portable pH/conductivity meter (AP85, Fisher Scientific). In the electrospinning trials, the solution was infused through a 10 mL syringe and tubing by a syringe pump (Harvard Apparatus 11 Plus) to an 18 gauge metal needle. The flow rate was 0.6 mL/h, the applied voltage was 14 to 15 kV, the needle–collector distance was 20 cm, and the humidity was maintained at 35 to 40%. The rotating speed of the customized collector was 5000 rpm. Each trial was conducted at room temperature for 5 hours. At the end, electrospun samples containing fibroin were placed in a vacuum desiccator with methanol for 48 hours to induce the conformational transition of fibroin to make it water-insoluble.

Tecoflex SG-80A and Tecophilic SP-60D-20 were purchased from Lubrizol Advanced Materials Inc. (Cleveland, OH). Anhydrous tetrahydrofuran (THF), anhydrous acetonitrile, sodium chloride, potassium chloride, sodium phosphate dibasic, and potassium phosphate monobasic were products of Sigma-Aldrich Chemical Company (St. Louis, MO). Poly(D,L-lactide-co-glycolide) 5050DLG1A (1-2 week hydrolysis rate), 5050DLG7E (1-2 month hydrolysis rate), and 6535DLG7E (3-4 month hydrolysis rate) were obtained from SurModics Pharmaceuticals Inc. (Birmingham, AL). N,N’-Dibutyl-1,6-hexanediamine (DBHD) was purchased from Alfa Aesar (Ward Hill, MA). DBHD/N₂O₂ was synthesized by treating DBHD with 80 psi NO gas purchased from Cryogenic Gases (Detroit, MI) at room temperature for 48 h, as previously described [46 (link)]. Phosphate buffered saline (PBS), pH 7.4, containing 138 mM NaCl, 2.7 mM KCl, and 10 mM sodium phosphate was used for all in vitro experiments.