2016 Volume 29 Issue 6 Pages 823-829
Photodynamic therapy (PDT) has drawn wide attention in intensive preclinical and clinical cancer therapy due to its noninvasive nature. A simple and facile synthesis of highly efficient delivery system for photosensitizers (PS) with visualized tumor environment is hence critical. Herein, a simple, safe and promising fluorescent probe, star-shaped poly(glutamic acid) with a porphyrin core (SPPLGA) was synthesized via ring-opening polymerization of β-benzyl-L-glutamate N-carboxyanhydride monomer with 5, 10, 15, 20-tetrakis-(4-aminophenyl)-21H, 23H-porphyrine (TAPP) as the initator, followed by the deprotection of benzyl groups on poly(benzyl-L-glutamate). The structure of this novel polymer was thoroughly studied by Nuclear magnetic resonance spectroscopy(NMR), Gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FT-IR). Such star-shaped poly(glutamic acid) with porphyrin core could self-assemble into micelles in aqueous solution and exhibit pH-sensitive critical micelleconcentration. It was observed that with the decrease in pH, the fluorescence intensity of the SPPLGA increased. On the other hand, the incorporation of poly(glutamic acid) not only improved solubility of porphyrin in water, but also enhanced the production efficiency of the singlet oxygen (about double that of porphyrin). Those results suggest that these polymer, as promising pH-responsive and tumor-selective photosensitizers, are very promising for PDT and can potentially be used as ″theranostics″ for future cancer prognosis and therapeutic planning.
