Biomimetic star-shaped porphyrin-cored poly(L-lactide)-b-glycopolymer block copolymers for targeted photodynamic therapy

Porphyrin-cored poly(l-lactide) (SPPLA) was successfully synthesized from ring-opening polymerization (ROP) of l-lactide initiated with porphyrin core. Then, SPPLA was coupled with benzylsulfanylthiocarbonylsufanylpropionic acid (BSPA), and a macro-reversible addition-fragmentation chain transfer (macroRAFT) polymerization agent SPPLA-BSPA was obtained. Finally, star-shaped porphyrin-cored poly(l-lactide)-b-poly(gluconamidoethyl methacrylate) (SPPLA-b-PGAMA) block copolymers were synthesized via RAFT of unprotected gluconamidoethyl methacrylate (GAMA) in 1-methyl-2-pyrrolidinone (NMP) solution at 70 A degrees C. The structure of this block copolymer was thoroughly studied by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Under the irradiation, such SPPLA-b-PGAMA copolymer exhibits efficient singlet oxygen generation and indicates high fluorescence quantum yields. Notably, with UV-vis and dynamic light scattering (DLS) analysis, SPPLA-b-PGAMA showed a very specific recognition with concanavalin A (ConA). Particularly, MTT shows that the cytotoxicity of SPPLA-b-PGAMA against COS-7 cells was very low and, when given a longer irradiation time, more BEL-7402 cancer cells died, which will be investigated in this study.