Objective: To improve solubility and to reduce aggregation, ZnPcC4 was conjugated to a
third-generation poly-amidoamine dendrimer with amino end group (G3-PAMAM-NH2), which acts
as a novel photodynamic therapy (PDT) drug carrier system.
Methods: The phthalocyanines were synthesized by construction reaction. The nano drug was obtained
from the conjugation of ZnPcC4 to G3-PAMAM-NH2, using EDC and NHS as coupling
agents. The ZnPcC4@G3-PAMAM-NH2 conjugation was characterized by UV-Vis and MS. The 1O2
quantum yield of ZnPcC4@G3-PAMAM-NH2 in water was measured by the chemiluminescence
method. The in vitro PDT responses of the studied photosensitizers were studied in hepatocellular
carcinoma cell line HepG2 by MTT assay.
Results: At ZnPcC4/G3-PAMAM-NH2 raw ratio of 100/1, the ZnPcC4 conjugate had improved solubility
and reduced aggregation tendency in aqueous solution. At this optimum molar ratio, ZnPcC4-
G3-PAMAM-NH2 inhibited HepG2 cells, with a half-maximal inhibitory concentration of 1.67
µg/mL upon infrared light exposure. The controls, including dark conditions, or media as well as
G3-PAMAM-NH2 exposure, exhibited no inhibitory response.
Conclusion: The conjugation of phthalocyanine photosensitizer ZnPcC4 to poly-amidoamine dendrimer
G3-PAMAM-NH2 improved the PDT outcomes, in which the optimized binding ratio of
ZnPcC4 to G3-PAMAM-NH2 was 6:1.