Triphenylamine-substituted zinc porphyrin nanoparticles with photodynamic/photothermal activity for cancer phototherapy in vitro

An amphiphilic zinc porphyrin complex with a typical donor-acceptor (D-A) structure was synthesized, where the triphenylamine acted as a donor unit while the porphyrin was used as an electronic acceptor. Due to the presence of triethylene glycol moieties on the parent structure, Zn-TPAP could spontaneously assemble to the related nanoparticles (Zn-TPAP NPs) with improved hydrophilicity. The as-prepared Zn-TPAP NPs presented relatively uniform spherical particles with the average particle sizes around 160 nm, which was suitable for tumor accumulation benefiting from the EPR effect. Due to the aggregation of the porphyrin molecules in the assembled nanostructures, Zn-TPAP NPs displayed broadened and red-shifted absorption and quenched fluorescence relative to that of Zn-TPAP. In addition to ROS generation, Zn-TPAP NPs exhibited moderate photothermal effects and the photothermal conversion efficiency was measured as 29%. Zn-TPAP NPs showed good biocompatibility and could generate ROS in the A549 cells. Under light irradiation, Zn-TPAP NPs can efficiently kill cancer cells. Thus, Zn-TPAP NPs could be used as potential nanoagents for cancer treatment through the photothermal/photodynamic synergistic modes.