PicoGreen DNA quantification

To estimate the cell proliferation onto 3D-SFnws, DNA cellular contents were assessed by the Quant-iT PicoGreen dsDNA Kit (Thermo Fisher Scientific). Three specimens of HDFs cultured on 3D-SFnws were assessed at experimental days 3 and 15. After washing the cells in PBS, 8 ml of deionized water was added to the wells to detach and lyse the cells. Repeated vortexing and two freezing–thawing cycles improved cell lysis. DNA amounts were then fluorometrically measured at excitation λ 480 nm and emission λ 520 nm. A standard double strand DNA curve of known concentrations was used to calibrate the fluorescence intensities.