Trifluoroethanol

The following chemicals were used: “heavy” lysine-¹³C₆¹⁴N₂ (lys8) (Silantes (GmBH), arginine-¹³C₆¹⁴N₄ (arg10) (Silante, GmBH), 1.9 µm C18 AQ particles (Dr. Maisch), 1,1,1-Trifluoro-Ethanol (Sigma), Iodoacetimide (Sigma), TCEP (ThermoFisher) Tetrafluoro Acetic Acid (Optima-grade, Fluka), Acetonitrile (ACN) (Optima-grade, Fluka), ammonium hydroxide (HPLC-grade, Sigma), SB203580 (SelectChem), Doxycyline, H33342 and DAPI (Sigma). All antibodies used are described in Supplemental Table S2.

poly(ι-lactic acid) (PLLA) was purchased from Samyang (Seoul, Korea). Trifluoroethanol, dopamine hydrochloride, anti-mouse IgG biotin conjugate, anti-rabbit IgG biotin conjugate, alizarin red S, and p-nitrophenyl phosphate were purchased from Sigma (St. Louis, MO, USA). Isopropyl alcohol, and Tris-HCl were obtained from EMD Millipore (Billerica, MA, USA) and Alfa Aesar (Heysham, UK), respectively. Fetal bovine serum (FBS), penicillin/streptomycin, and phosphate-buffered saline (PBS) were purchased from Wisent (St. Bruno, QC, Canada). The Quant-iT Picogreen dsDNA Assay kit was purchased from Invitrogen (Carlsbad, CA, USA), and the QuantiChrom Calcium Assay kit was purchased from BioAssay Systems (Hayward, CA, USA). Hematoxylin and eosin was purchased from BBC Biochemical (Mount Vernon, MA, USA). The Live and dead assay kit and streptavidin-FITC were obtained from Molecular Probes (Eugene, OR, USA) and ebioscience (San Diego, CA, USA), respectively. VEGF ELISA development kits were purchased from PeproTech (Rocky Hill, NJ, USA). The primary antibodies OCT4, NANOG, and SOX2 were purchased from Abcam (Cambridge, UK). Hypoxia Probe LOX-1 was purchased from SCIVAX Corporation (Kanagawa, Japan).

One gram of gelatin (Sigma-Aldrich, Saint Louis, China) and 0.1 g of curcumin (Sigma-Aldrich, Saint Louis, China) were dissolved in 10 ml of trifluoroethanol (Sigma-Aldrich, Saint Louis, China) and stirred at room temperature for 2 h until they were completely dissolved to obtain a uniform spinning solution. For electrospinning, the spinning solution was loaded into a 10 ml syringe with a 20-gauge nozzle. The syringe was placed 10 cm from the collector (aluminum foil wrapped copper plate) and the feed rate was set to 1.5 ml per hour controlled by a syringe pump (Cole-Parmer, US). The DC voltage was set at 15 kV. The residual organic solvent of the prepared sample was removed by vacuum drying, and then the sample was processed by a cross-linking process. Namely, a 25% glutaraldehyde solution (Sigma-Aldrich, Saint Louis, China) and ethanol mixture (1% V/V) were placed together with the prepared nanofibrous mat in a vacuum desiccator at 24 °C for 24 h. After that, the cross-linked NM was rinsed with ultrapure water and lyophilized for 24 h. A gelatin NM without curcumin (Glt NM) was made in the same way as control for the subsequent experiments.

For the dissolution of EPS, 1.0 mg powder was mixed with 3.0 mL of various non-polar and polar solvents like chloroform (Sigma-Aldrich), trifluoroethanol (Sigma-Aldrich), dimethyl sulfoxide (Sigma-Aldrich), acetic acid (Sigma-Aldrich), and water. The mixtures were properly vortexed and solubilities were checked^{15 (link)}.