Synthesis of Chitosan-PEI

 Copolymer of CP was prepared according to the methods described by Gao et al. [8].

Dissolve 0.5 g Chitosan  in 20 ml of a 0.5% acetic acid solution

Adjust to pH 7.0

Stir overnight.

Add CDI 1,19-carbonyldiimidazole (pierce) at a molar ratio of CDI:CS amine = 2:1

http://www.sigmaaldrich.com/catalog/product/aldrich/21860
21860-5G, 29.00, 21860-25G 83.10

Stir for 1 h.

Add  PEI (1.8 kDa)  dropwise into the solution under stirring at a molar ratio of PEI:amine = 2:1.

Polymerize at room temperature (25uC) overnight.

Dialysis in water for 48 h.

Collect the powder by lyophilization.