Synthesis And Characterization Of A Novel Water-soluble And Thermoresponsive Phthalocyanine Polymer As Potential Photosensitizer For Photodynamic Therapy Of Cancers

Owing to the strong absorption in tissue-penetrating red light and high efficiency of generating singlet oxygen, phthalocyanines(Pc) have promising potential as second-generation photosensitizer for photodynamic therapy(PDT). Nevertheless, clinical application of phthalocyanines is substantially limited by poor water solubility, aggregation and insufficient selectivity for cancer cells. To address these issues, we have carried out a design and preparation of block copolymer based theranostic platform for tumor targeted delivery of phthalocyanines.In this work, the diblock copolymers, containing the same length of the hydrophilic block monomethoxy-capped poly(ethylene glycol)(MPEG) but with different number of NIPAM units were synthesized by utilizing atom transfer radical polymerization(ATRP). Then the thermoresponsive diblock copolymers were first functionalized with maleic anhydride by ATRP and their subsequent reaction with zinc(II) tetraaminophthalocyanine(ZnTAPc) aiming at the formation of a water-soluble and thermoresponsive phthalocyanine polymer photosensitizers for potential photodynamic therapy. The structure of ZnTAPc-polymer was elucidated by 1H NMR, UV-Vis and GPC. And as the experimental results suggest, the ATRP technique provides the possibility of tuning the lower critical solution temperatures(LCST) of the polymer easily by changing composition of EG and NIPAM, What is more, ZnTAPc brings the PDT effect and ZnTAPc-polymer generate singlet oxygen species with good quantum yields, which were believed to be the major cytotoxic reactive oxygen species(ROS) for PDT. This water-soluble thermoresponsive ZnTAPc-polymer provides a new material for photodynamic therapy and has potential application in biomedical field.