Editing Synthesis Chitosan Arginine (section)

== Preparation &nbsp;of Octaarginine R8 -CS  ==

Octaarginine (R8) was synthesized by Fmoc (9-fluor-enylmethyloxy-carbonyl)-solid-phase peptide on a&nbsp;Rink amide resin (Futaki et al. 2001). It was conjugated to chitosan via carbodiimide chemistry, as&nbsp;shown in Scheme 1 (Liu et al. 2004). Briefly, the&nbsp;carboxyl group of R8 was activated by EDC/NHS&nbsp;dissolved in MES buffer (0.1 M MES, pH 6.0) at room<br>temperature for 10 h, with '''1:5:2 '''molar ratio of&nbsp;octaarginine:EDC:NHS. The '''amino end of R8 was&nbsp;protected by acetyl'''. Chitosan was then added and&nbsp;allowed to react for another 24 h by stirring. The&nbsp;reaction was quenched by adding hydroxylamine to a&nbsp;final concentration of 10 mM, and the pH value&nbsp;was brought to 8.0 with NaOH. The resulting solution&nbsp;was dialyzed by using Spectra/Pro membrane&nbsp;(MWCO = 12,000–14,000) against distilled water&nbsp;for 4 days before lyophilization. Herein, two conjugation degrees of R 8 -CS were prepared with molar&nbsp;ratios of R8 to chitosan residues as '''1:8, 1:4,''' which&nbsp;were denoted as '''R 8 -CS1 and R 8 -CS2''', respectively. 

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[[Image:Octaarginine Chitosan.png]] 

[[Image:Octaarginine Chitosan transfection efficiency.png]] 

[[Category:Paul]] [[Category:Transfection]]