Poly ε caprolactone

Microfiber meshes with and without IGF-1 were fabricated by electrospinning.^{44 ,45 (link)} Briefly, a 5:1 (w/w) mixture of polylactide-co-glycolide (PLGA 85:15, DL, $\overline{M_w}\approx 123.6\text{ kDa}$ , Lakeshore Biomaterials) and poly-ε-caprolactone (PCL, $\overline{M_n}\approx 70,000–90,000$ , Sigma-Aldrich) was solubilized in a 3:2 (v/v) mixture of dichloromethane (DCM, Sigma-Aldrich) and N,N-dimethylformamide (DMF, Sigma-Aldrich). The polymer solution (32% w/v) was vortexed for 1 hour. After adding bovine serum albumin (BSA, 5% w/w, Sigma-Aldrich) and IGF-1 (5 ng/mL, Gibco Laboratories), it was mixed for another hour. The solution was then drawn into a 5 mL syringe with a stainless steel blunt tip needle (18G, Becton Dickinson), placed 10 cm from a stationary collecting plate, and electrospun at 8−10 kV (Fig. 1). The syringe pump (Harvard apparatus) was operated at 1 mL/h to form PLGA:PCL-blend fibers, and at 0.8 mL/h for blends with IGF-1 at either 50 or 100 ng/mg IGF-1 dose.
The as-fabricated meshes were characterized using scanning electron microscopy (SEM, 2 kV, Hitachi 4700). Before imaging, the samples were sputter-coated (Cressington 108auto) with gold-palladium (10 s, 2 nm) to reduce charging effects. Fiber diameter (n = 3 meshes/group, 20−30 fibers per mesh) was quantified via analysis of SEM micrographs using ImageJ (National Institutes of Health).^{46 (link)}