Photophysical property of the pyridyl and pyrimidinyloxy silicon (IV) phthalocyanines and their morphology of polymeric nanoparticles

Phthalocyanines (Pcs) are extensively studied by many scientists because of their interesting optical, electrical properties, and good thermal stability. The unsubstituted Pcs can present solubility and aggregation behaviour problems for their limiting applications. In our study two pyridyl and pyrimidinyloxy silicon (IV) phthalocyanines were synthesized. Their photophysical properties were examined by UV-Vis, steady-state and time-resolved fluorescence spectroscopic methods. The positions of Q band were observed at 670 nm for two phthalocyanines. Compared with silicon phthalocyanine dichloride (SiPcCl2), the fluorescence intensities and lifetimes of pyridyl and pyrimidinyloxy silicon (IV) phthalocyanines increased. In order to improve biocompatibility and tumor-targeted delivery, the hydrophobic dendritic phthalocyanine were encapsulated by diblock amphiphilic copolymer poly (N’-benzyl oxygen carbonyl lysine)-poly (ethylene glycol)-poly (N’-benzyl oxygen carbonyl lysine) (PLL(Z)-PEG-PLL(Z)) to form the polymeric nanoparticles. The morphology of two nanoparticles were investigated by using atomic force microscope. The polymeric nanoparticles were spherical with the diameter at about 35 nm. The polymeric nanoparticle SiPc(OR2)2@PLL(Z)-PEG-PLL(Z) would be the promising third-generation photosensitizer (PS) for photodynamic therapy (PDT).