Preparation of N-butyl chitosan and study of its physical and biological properties

N‐Butyl chitosans with different substitution degrees were prepared by solid–liquid heterogeneous reaction, varying the ratio of chitosan to butyl bromide. FTIR and free amino percentage analysis confirmed that the substitution reaction occurred primarily on NH2 moieties. X‐ray diffraction results of the chitosan derivatives showed that the hydrogen bonds were weakened by the incorporation of pendant alkyl. N‐Butyl chitosan films exhibited a higher elastic modulus, a lower percentage of elongation at break, decreased equilibrium swelling ratios, and slightly increased surface hydrophobicity compared to chitosan film. The results of ELISA indicated that the adsorption amount of fibronectin on butyl chitosan films was much higher than on chitosan film, which was maybe due to the rearrangement of hydrophilicity/hydrophobicity after modification. The MTT assay suggested that the viability and proliferation of osteoblast cells on N‐butyl chitosan films were higher than that on chitosan film. These results suggest that N‐butyl chitosan is a promising candidate biomaterial for bone regeneration. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1016–1024, 2005