*2.3. Cell Culture Studies*

NIH 3T3 murine fibroblast cells (Sigma Aldrich, Gillingham, UK) were used for proliferation and adhesion assay on the meshes sterilized with UV light. Cells were seeded on PS, PA6, and PS-PA6 composite fibers, and on the bottom of a 24-well plate (TCPS) as a reference, with a concentration of <sup>2</sup> <sup>×</sup> 104 cells per sample. Samples with cells were incubated at H = 90%, T = 37 ◦C, and CO2 set to 5% up to 7 days. Cell proliferation and adhesion assays were performed using MTS (CellTiter 96®® AQueous One Solution Cell Proliferation Assay, MTS, Promega, Madison, WI, USA). The cell morphology was examined with SEM. NIH 3T3 cells were cultured in Dulbecco's Modified Eagle Medium (DMEM with 4.5 g/L D-Glucose, Gibco, Paisley, UK), supplemented with 10% of Fetal Bovine Serum (FBS, Sigma Aldrich, St. Louis, MO, USA), 1% of L-Glutamine solution (Sigma Aldrich, St. Louis, MO, USA), 2% of antibiotics (Penicillin-Streptomycin, Sigma Aldrich, St. Louis, MO, USA), and 1% of amino acids (Mem non-essential Amino Acid solution 100x, Sigma Aldrich, St. Louis, MO, USA). The medium was changed three times a week.
