Using L-lysine as raw material, Polylysine (PLL) was synthesized through four steps. The structures of intermediums and the final product were confirmed by IR and ¹H NMR. Furthermore, some key synthetic steps were optimized in the process. On the basis, response ability to environmental pH of PLL structures was investigated by SEM and circular dichroism spectra. Experimental results indicated that polypeptide structure of PLL has good response ability to pH of environment. Under different pH conditions, distinct morphology was formed. Under acidic conditions, PLL presented a specific coil conformation, whereas orderly pine needle was observed under alkaline conditions.

Key words: polylysine, N-carboxy-(N^ε-benzyloxycarbonyl)-L-lysine anhydride (NCA), synthesis, pH, response