Fig. 1From: Immobilization of Gelatin onto Poly(Glycidyl Methacrylate)-Grafted Polycaprolactone Substrates for Improved Cell–Material InteractionsThe density of amine groups of the aminolyzed PCL film surface as a function of aminolysis time as determined by the ninhydrin assay. The analysis reaction of PCL films proceeded at 40 °C in 10 wt% 1,6-hexanediamine/2-propanol solution. Error bars represent the standard deviation over three separate PCL films. The optimized aminolysis time was observed at 1 h with NH2 density at about 0.265 μmol/cm2Back to article page