Capa 6800

A PCL solution was prepared from medical-grade PCL granules (CAPA^® 6800, average 80,000 MW, Perstorp, Sweden) dissolved at a 12% w/v concentration in a 65:35 solvent mixture of Chloroform (99.2% purity, stabilized with 0.6% ethanol, VWR, Radnor, PA, USA) and Dimethylformamide (100% purity, VWR, Radnor, PA, USA) under mild stirring overnight at room temperature. The supplier reported a theoretical density for the PCL of ρ0 = 1.145 g/cm³.
A PEO solution was prepared from PEO granules (35,000, FLUKA Chemicals, Buchs, Switzerland) dissolved at a 30% w/v concentration in distilled water under mild stirring at 50 °C for two days. The supplier reported a theoretical density for the PEO of ρ0 = 0.45 g/cm³.
1-PWD formulation, obtained by API spray dispensing directly from its container, was then mixed with the PEO solution (30 wt%) under magnetic stirring until the incorporation of a 4% product.
Biomedical scaffolds were fabricated with electrospinning using a pilot scale electrospinning station (Fluidnatek LE100, Bioinicia, Valencia, Spain) using different variations of a process recipe, provided in-kind by the company Nanofaber srl (Rome, Italy), varying the applied voltage and flow rate (FR). The relative humidity (RH) and ambient temperature during the deposition process were recorded.

Poly(ε-caprolactone) (PCL) CAPA 6800, with an average molecular weight of 84,000 g/mol, a density of 1.15 g/cm³, and a melt flow index of 3 g/10 min (160 °C, 2.16 kg) was selected as the matrix and purchased from Perstorp (Malmö, Sweden). The sodium borosilicate hollow glass microspheres (HGM) iM16K, with a density of 0.46 g/cm³, average diameter of 20 µm, and crush strength of 16,000 psi, were used as filler and supplied by 3M (Saint Paul, MN, USA). The coupling agent used for filler modification was an APTES [(3-aminopropyl)triethoxysilane] (purity ≥ 98.5%) supplied by Sigma-Aldrich (Milan, Italy).

The commercially available poly(ɛ-caprolactone) (PCL) (Capa 6800, Mw = 80 000 g⸱mol⁻¹) was purchased from Perstorp (Malmö, Sweden). The free radical initiators dicumyl peroxide (DCP) (Peroxan DC-P+) and di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB) (Peroxan BIB-1) were supplied by Pergan GmbH (Bocholt, Germany).

Following the procedure according to Wulf et al. [22 (link)], 1 g PCL (Capa™ 6800, Perstorp, Warrington, UK) or 1 g P(3HB) (Helmholtz-Zentrum für Umweltforschung, UFZ, Leipzig, Germany) were dissolved in 25 mL chloroform to fabricate polymer sheets. After several washing steps (two days in methanol, two days in distilled water, three times for 60 min each in 0.05% Tween 20, three times for 60 min each in distilled water), the sheets were dried in a vacuum cabinet drier at 40 °C and 40 mbar for seven days. In order to be able to use them in a circular form in vitality and proliferation assays, foils with a diameter of 6.4 mm were stamped out of the polymer sheets, sterilised using 70% ethanol, and air-dried under laminar flow. In order to characterise the foils’ surface, ESEM analyses were performed.

The PCL pellets (CAPA6800, Perstorp Ltd, Sweden, Mw = 80,000 kDa) used in this experiment are medical grade (approved by the United States Food and Drug Administration), and melt at 60°C. Lithium fluoride (LiF ≥99%) and 2,2,2-trifluoroethanol (TFE) were purchased from Sigma (St. Louis, MO). Hydrochloric acid (HCl), absolute ethyl alcohol, and absolute methyl alcohol were purchased from Aladdin Reagents (Shanghai) Co., Ltd., China. The Ti₃AlC₂ powder was purchased from Jilin 11 technology Co., Ltd. All reagents were analytical grade.

The poly(ε-caprolactone) used in this research work was CAPA 6800 (high-molecular-weight linear polyester, Mw: ~80,000 g/mol), purchased from Perstorp (Malmö, Sweden). Apatite whiskers (HAP) obtained as multiphasic calcium phosphate were prepared using a methodology described earlier [9 (link),24 (link),36 (link)]. L-Lysine (crystallized, >98%) was purchased from Sigma-Aldrich (St. Louis, MO, USA). Sodium chloride and 1,4-dioxane were supplied by POCH (Gliwice, Poland). The standards of L-Lysine, hydrochloride, ammonia formate, formic acid, and acetonitrile (HPLC-grade) were purchased from Sigma-Aldrich. All aqueous solutions were prepared using Milli-Q water (Millipore, Bedford, MA, USA).

Polycoaprolactone (PCL), Capa 6800 with a melt flow rate of 3 g/10 (190 ⁰C at 2.16 kg), was purchased from Perstorp. Polylactic acid (PLA), 2003D with a melt flow rate of 5–7 g/10 (210 ⁰C at 2.16 kg) was supplied by Natureworks LLC.