Editing Synthesis Chitosan Arginine (section)

=== Gao Method<br>  ===

Chitosan&nbsp; (Mv  5000, degree of deacetylation  80%) can be modifed with arginine using EDC and NHS as coupling agents<br> 

Dissolve 0.3 g of arginine and 1 g of CS in 50 ml of N, N,N H , N H -tetramethylethylenediamine (TEMED)/HCl buffer solution ( pH 4.7).<br> 

Add NHS (0.14 g) and EDC (0.6 g) to this solution <br> 

Stir magnetically for 24 h at room temperature.<br> 

Dialyse (2000 MWCO) against distilled water for five days.<br> 

Lyophilization. <br> 

The substitution degree of arginine in CS&nbsp; is estimated by elemental analysis (C: 45.06%, N: 12.47%, H: 6.83%) to be 20.1%.<br> 

<br> 

Dissolve L-Arg (0.3 g) in distilled water (10 mL). N-hydroxysuccinimide<br>(130672-5G, 16.60; 130672-25G, 37.40, 130672-100G, 91.30)

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were added to the&nbsp;solution, respectively, at a fixed molar ratio of 1:1:3, to activate the carboxyl group of L-Arg. The pH&nbsp;of the resultant solution was adjusted to 6 with 1% acetic acid and 1% NaOH solution. The carboxyl&nbsp;group of L-Arg was activated for 2 h. Secondly; chitosan (1 g, MW 5 kDa) was dissolved in 1% acetic acid solution (100 mL). The pH was adjusted in the same manner as L-Arg solution with 1% NaOH&nbsp;solution. The activated L-Arg solution was added to the chitosan solution to react at ambient&nbsp;temperature with continuous stirring for 48 h. The resultant solution was dialyzed (MWCO = 3,500)&nbsp;against distilled water for 48 h, then lyophilized. The final product was named as N-ArgCS-A. Using&nbsp;the same method for preparation of N-ArgCS-A, and other chitosans (MW 10 kDa and 20 kDa) NArgCS-B and N-ArgCS-C, were produced, respectively.