Preparation of a star-shaped copolymer with porphyrin core and four PNIPAM-b-POEGMA arms for photodynamic therapy

Abstract

A series of thermosensitive star-shaped copolymers THPP-(PNIPAM-b-POEGMA)4 with 5, 10, 15,20-tetrakis-(4-hydroxyphenyl)-21H,23H-porphyrin (THPP) core and four poly(N-isopropy-lacrylamide)-b-poly(oligo(ethylene glycol) mono methyl ether methacrylate) (PNIPAM-b-POEGMA) arms were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The low critical solution temperatures (LCSTs) of THPP-(PNIPAM-b-POEGMA)4 with different molecular weights were 37.5 °C, 39.9 °C and 41.9 °C respectively, which depending on the hydrophilic POEGMA contents of copolymers. The micellar structures of copolymers could be formed above the LCSTs. The MTT study indicated that THPP-(PNIPAM-b-POEGMA)4 and THPP showed no significant cytotoxicity toward HeLa cells and L929 cells. And THPP-(PNIPAM-b-POEGMA)4 under light irradiation showed photodynamic activity which photo-toxicity toward HeLa cells was stronger than THPP.