Photodynamic therapy with hyperbranched poly(ether-ester) chlorin(e6) nanoparticles on human tongue carcinoma CAL-27 cells

Background: Hyperbranched polymers represent a new class of drug-delivery vehicle that can be used to prepare nanoparticles with uniform size distribution. Methods: In this study we prepared covalent conjugates between the photosensitizer chlorin(e6) and hyperbranched poly(ether-ester), HPEE. HPEE-ce6 nanoparticles were synthesized by carbodiimide-mediated reaction between HPEE and ce6, and characterized by ultraviolet-visible absorption spectroscopy (UV-Vis), and transmission electron microscopy (TEM). The uptake and phototoxicity of HPEE-ce6 nanoparticles towards human oral tongue cancer CAL-27 cells was detected by confocal laser scanning microscopy (CLSM) and MTT assay, respectively. Results: The absorption peak of HPEE-ce6 nanoparticles was red-shifted 12-nm compared with ce6, and TEM showed uniform nanoparticles with a diameter of 50-nm. HPEE-ce6 nanoparticles were taken up by CAL-27 cells after 4 h incubation and localized in the cytoplasm. The MTT assay showed a significantly (P < 0.05) higher phototoxicity compared to free ce6 after 12 J/cm(2) of 660-nm laser illumination. Conclusions: This is the first time to our knowledge that hyperbranched polymers have been used in PDT drug delivery. (c) 2011 Elsevier B.V. All rights reserved.