Ingeo 4032d

Bio-blends were prepared using as matrix two forms of PLA. One of the PLA form is a commercial Poly(lactid acid) grade (Ingeo 4032D^®) from NatureWorks (Arendonk, Belgium), with a D-lactide molar content of 2%, a M_n of 90,000 g/mol and M_w of 181,000 g/mol, and a melting temperature (T_m) of 167 °C.
The second type of matrix was a rheologically modified form of the previous PLA, referred to later on as PLA_REx. This modification was obtained by a reactive extrusion (REx) process following the same procedure and conditions previously reported in [36 (link)], using as reagent a styrene-acrylic multifunctional-epoxide oligomeric agent (Joncryl-ADR-4400^®, kindly supplied by BASF, Ludwigshafen, Germany), with an epoxy equivalent weight of 485 g/mol and a functionality of 14. Under these processing conditions, chain extension and sparsely three-arm star branching are promoted in PLA which results in a content of approximately 24% w/w of modified chains, causing an increase in its melt elasticity [18 (link),37 (link)].
As dispersed phase, a bio-based PA10.10 (Zytel RS LC1000 BK385) was used, manufactured by DuPont (Wilmington, DE, USA), with a melting temperature (T_m) of 200 °C, a M_n of 11,000 g/mol, and M_w of 33,000 g/mol.
The blend compositions and codes used along this work are summarized in Table 2.

Hydroxyapatite (needle-shaped particles, 90 nm, Ca/P ratio of 1.67, “Polistom”, Moscow, Russia), Polylactide (pellets, molecular weight of 110 kg/mol, Ingeo 4032D by Natureworks LLC, Minnetonka, MN, USA). Calcium Nitrate Tetrahydrate (RusHim, Moscow, Russia), Tetraethyl Orthosilicate (TEOS) (EKOS-1, Moscow, Russia, 99.99%, TU 2637-187-44493179-2014), Glycine (RusHim, Moscow, Russia), Concentrated Nitric Acid (70%, RusHim, Moscow, Russia) and deionized water was used for the synthesis of wollastonite.

Poly-(d,l)-lactide (PLA, Ingeo 4032d, NatureWorks, 650 Industrial Park Drive, PO Box 564 Blair, NE 68008, USA) -gelatine (ServiceBio, Wuhan, China) solutions of 100 mg/mL and 200 mg/mL of 1,1,1,3,3,3-hexafluoro-2-propanol (HFiP, 105228-2KG, Sigma-Aldrich, St. Louis, MO, USA), respectively. The PLA-gelatine solutions were composed through combination at 1:1 and 1:3 vol. % ratios. For instance, mat A is PLA-gelatin (100 mg/mL) (3:1), mat B is PLA-gelatine (100 mg/mL) (1:1), mat C is PLA-gelatine (200 mg/mL) (3:1), and mat D is PLA-gelatine (200 mg/mL) (1:1). Electrospinning was conducted with an acceleration voltage of 30 kV and a flow rate of 1 mL/h using an HSW NORM-JECT syringe (Henke Sass Wolf, Noerten-Hardenberg, Germany) at a distance of 30 cm from the counter electrode on a MECC NF 500 (MECC CO, Kyoto, Japan) at a temperature of 25 °C and 45–55% humidity. A 22 gauge stainless steel needle was employed as the nozzle, and an emitting electrode of positive polarity, alongside a ground electrode, was connected to a flat static collector. A polymethylmethacrylate (PMMA) dielectric collector was utilised to acquire freestanding mats positioned 10 cm from the counter-electrode. The mats that were 150–300 μm thick were deposited into Petri dishes 9 cm in diameter (Perint, St. Petersburg, Russia). Subsequently, the dishes were incubated for 24 h at 30 °C.

Dichloromethane (Manufacturer: LLC “PKF Galreahim”, Moscow, Russia) was used as a solvent to dissolve the polylactide. Polylactide (molecular weight of 110 kg/mol, Ingeo 4032D by Natureworks LLC) in pellet form was used as the main material for the preparation of the scaffold. Hydroxyapatite (HA needle particles 90 nm in size, Ca/P ratio of 1.67, “Polistom”, Moscow) was used as a component to increase the bioactivity of the product. Food-grade sodium chloride (NaCl) in granulometric form (up to 0.8 mm), having a mass fraction of not less than 99.7%, was used as a pore-forming agent, and was purchased from LLC “TDS”, Podolsk, Moscow region, Russia.

Phosphate glass fiber yarns with the chemical composition of P48-B12-Ca14-Mg17-Na1-Fe8 (the numbers indicate the molar percentage of each oxide of elements in the phosphate glass network) was supplied by Sinoma Co., Ltd, Nanjing, China. The fibers have a diameter of 9–13 μm. Rod-like magnesium oxide (MgO) microparticles were supplied by Kaishefeng^®, Shanghai, China. The microscopic image of MgO was shown in Figure S1. The polylactic acid of Ingeo^® 4032D (Natureworks^®, Minnetonka, MN, United States) was used in granule form. Tris(hydroxymethyl)aminomethane and 1.0 mol/L hydrochloric acid (HCl) aqueous solution were supplied by Sinopharm Chemical Reagents Co., Ltd, Shanghai, China. 1.0 mol/L nitric acid (HNO₃) solution and lanthanum chloride (LaCl₃) were supplied by Aladdin Reagents, Shanghai, China. 1000 μg/mL standard solutions of Ca²⁺ and Mg²⁺ were supplied by Guobiao (Beijing) Testing and Certificate Co., Ltd, Beijing, China.