N-Carboxyethyl chitosan was synthesized according to the
method reported by us earlier [28]. Briefly, 4.0 g of chitosan (corresponding
to 17 mmol NH2) was dissolved in 250 mL of water
containing 7.7 mL acrylic acid at 50 ◦C under constant stirring for
2 day. After that, 1 N aqueous NaOH was added to the reaction
A 2.5% (w/v) CECS solution was prepared by dissolution of 2.5 g
CECS in 100 mL distilled water. PVA (13.5 g) was dissolved in 150 mL
distilled water at 80 ◦C with vigorous stirring for a period about 4 h,
forming a PVA solution at a concentration of 9% (w/v). The CECS
solution was mixed with the PVA solution at CECS/PVA weight ratio
40/60. Silk fibroin nanoparticles were added into the CECS/PVA
solution at weight ratio 4 or 8% of silk fibroin nanoparticles to
CECS/PVA, dispersed uniformly by stirring at high speed.