Porcine type I collagen (molecular weight 300 kDa) was dissolved in water (0.5% w/v) and deoxygenated by bubbling argon through the solution. The pH was adjusted to 10 using NaOH (2 м). After cooling the reaction mixture in an ice bath, furfuryl glycidyl ether (FGE) (three molar equivalents with respect to lysine and arginine amines considering 114 amines from lysine and arginine combined per collagen molecule) was added dropwise while stirring and maintaining the pH at 10 by intermittent addition of NaOH (2 м). The reaction mixture was left for stirring at room temperature overnight in dark under argon atmosphere. The reaction mixture was then purified by dialysis using 12-14 kDa cutoff dialysis tubes (Spectrum Laboratories, Inc., CA, USA) against deionized water with pH 10 for two days and then against deionized water with pH 4.5 for another two days. The purified collagen furan solution was lyophilized to obtain an off-white fluffy solid which was kept at -20 °C under argon until further use.