A non-aggregated zinc(II) phthalocyanine with hexadeca cations for antitumor and antibacterial photodynamic therapies

With a view to developing highly efficient photosensitizers for both antitumor and antimicrobial photodynamic therapies, herein, we reported a super cationic zinc(II) phthalocyanine (Pc4), which was prepared through the quaternization of the N, N-dimethyl-3-aminophenoxyl-hexadeca-substituted precursor Pc3. Meanwhile, two disubstituted analogues (Pc1 and Pc2) were also prepared as controls. The cationic Pc2 and Pc4 had higher photoactivities including fluorescence and singlet oxygen than the neutral counterparts Pc1. and Pc3, probably because of the inhibition of intramolecular charge transfer (ICT) effect of the amino groups. With the bulky steric effect and high hydmphilicity, Pc4 presented non-aggregated behavior in aqueous solutions. Therefore, it exhibited the highest in vitro photodynamic activity toward HepG2 cancer cells with an IC50 value as low as 0.04 mu M. Furthermore, Pc4 showed a highly efficient in vivo PDT effect on H22 tumor-bearing mice with 98.7% tumor growth inhibition. In addition, Pc4 also exhibited an excellent in vitro and in vivo photodynamic inactivation against S. aureus. The results indicate that the non-aggregated hexadeca-cationic Pc4 could serve as a promising photosensitizer for both antitumor and antimicrobial photodynamic therapies.