Formation of a DNA/N-dodecylated chitosan complex and salt-induced gene delivery

An N‐dodecylated chitosan (CS‐12) was synthesized from dodecyl bromide and chitosan and was assembled with DNA to form a polyelectrolyte complex (DNA/CS‐12 PEC). UV was used to examine the thermal stability of DNA embedded in PEC. The results indicate that the incorporation of dodecylated chitosan can enhance the thermal stability of DNA. The analysis of AFM image shows that PEC develops a globule‐like structure composed of 40–115 DNA molecules. Dissociation of PEC was investigated by the addition of low molecular weight electrolytes. The added small molecular salts dissociate the PEC, inducing DNA to release. The ability of Mg2+ to dissociate PEC is greater compared to that of Na+ and K+. From AFM images, it can be visualized that DNA remains intact and undamaged due to the protection from DNase offered by alkylated chitosan. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3391–3395, 2001