“…These polymers mainly include natural ones such as chitosan, [115][116][117][118][119][120] gelatin, [121][122][123] silk broin, 118,124,125 sodium alginate, 126,127 and synthetic polymers such as poly(3-caprolactone), [128][129][130][131][132] poly(vinyl alcohol), 119,125,133 poly(ethylene oxide), 120,127,131 poly(vinyl pyrrolidone), 132 polyurethane 126 and polylactic acid. 134 4.1 Natural polymers 4.1.1 Chitosan. Chitosan (CS) is a natural polymer derived from chitin.…”