Poly(amino acid)-b-poly(N,N-diethylacrylamide)-b-poly(amino acid) conjugates of well-defined structure

Carboxy-terminated oligomers of N,N-diethylacrylamide (DEAAm) with low polydispersity were synthesized by group-transfer polymerization. The oligomers were conjugated with the N terminus of epsilon-N-CBZ-protected poly(lysine) and s-CBZ-protected poly(L-cysteine). The resulting conjugates precipitated in a narrow region of lower critical solution temperatures (LCST) around 29 degrees C. The LCST of poly(lysine)-polyDEAAm-poly(lysine) conjugates was pH-independent and independent of the lengths of poly(lysine) segments. Water-soluble nonstoichiometric conjugate-DNA complexes precipitated above the conjugate's LCST. Covalent complexes of human albumin and poly(cysteine)-polyDEAAm-poly(cysteine) conjugates showed temperature-sensitive behavior in aqueous solutions.