Synthesis and characterization of a hydrophobically modified copolymer of N-isopropylacrylamide and glycinyl acrylamide

A new type of pH- and temperature-sensitive polymer is synthesized. This polymer possesses not only temperature-sensitive groups and pH-responsive groups but also hydrophobic groups consisting of a pyrene group linked to a secondary amide nitrogen also carrying an octadecyl chain. The resulting copolymer, poly-(N-isopropylacrylamide) (PNIPAM)-Gly-Py, is a high effective modulator of the release of dyes entrapped in liposomes. Moreover, it improves the efficiency of cytoplasmic delivery of liposome-encapsulated dye. The synthesis and chemical characterization of this polymer and of a copolymer of NIPAM and glycine acrylamide are described.