Synthesis,Spectroscopic Properties,and Photodynamic Anticancer Activities of Novel Arginine-modified Silicon(Ⅳ) Phthalocyanines

We design and synthesize a series of novel silicon(IV) phthalocyanines(SiPcs, 1 a, 2 a, 1 b, and 2 b) axially conjugated with arginine or arginine-containing oligopeptides(Arg-Arg, Cys-Arg, Cys-Arg-Arg) through ester or ether linkers to demonstrate the effects of substituents and coupling ways on the spectral behaviors and photodynamic activities. The ester-linked SiPcs(1 a and 2 a) show slight red-shift, higher fluorescence emission and singlet oxygen generation compared to the ether-linked analogues(1 b and 2 b) due to the stronger electron-withdrawing ability of the ester group, suggesting that electronic effect of the linkers plays an important role in their spectral properties. The introduction of arginine could effectively reduce the aggregation of phthalocyanine in aqueous solutions. With higher cellular uptake and plasma membrane localization ability, 1 b and 2 b exhibit significantly higher photocytotoxicity against both HepG2 and Hela cells. Moreover, the in vivo fluorescence imaging suggests that 2 b is the most specific toward H22 tumor-bearing ICR mice, and it shows efficient tumor growth inhibition with the tumor inhibition rate up to 93%. Thus, this work would provide a new reference for the development of phthalocyanine-based photosensitizers.