Synthesis, Characterization and pH Sensitivity of N-octyl-N’-(2-carboxyl–cyclohexamethenyl) Chitosan

OBJECTIVE To synthesize a series of amphiphilic chitosan derivatives using pH-sensitive amide as spacer. METHODS The pH-sensitive chitosan graft copolymers with octyl and carboxylbenzoyl groups as hydrophobic and hydrophilic moieties were synthesized. The chemical structure of galactosylated chitosan was characterized by FTIR, ¹H-NMR and ¹³C-NMR. The physical properties were measured by XRD and DSC. RESULTS Seven pH-sensitive N-octyl-N’-(2-carboxyl-cyclohexamethenyl) chitosan derivatives were synthesized. The micelles formed by N-octyl-N’-(2-carboxyl-cyclohexamethenyl) chitosan were found to be highly sensitive to mildly acidic pH and reasonably stable at physiologic pH by UV-visible spectrophotometer. CONCLUSION This pH-sensitive polymeric micelle with controlled pH sensitivity may applied in “smart” drug delivery systems for constructing pharmaceutical nanocarriers capable of specific release of their cargo at certain pathological sites in the body (tumors, infarcts) or intracellular compartments (endosomes, cytoplasm) demonstrating decreased pH.