Near-infrared light triggered liposomes combining photodynamic and chemotherapy for synergistic breast tumor therapy.

Photodynamic therapy (PDT) as a promising noninvasive and effective treatment modality has been clinically approved for cancer therapy. However, the poor selectivity of tumor and hypoxia-induced resistance constrain PDT efficacy immensely. To further enhance PDT's potency, we developed a drug delivery system based on liposome combining PDT and chemotherapeutics. The lipophilic IR780 was loaded into the lipid bilayer while hydrophilic chemotherapeutic agent tirapazamine (TPZ) was encapsulated in the hydrophilic core. IR780 could generate reactive oxygen species and hypoxic microenvironment in local site because of the continuous consumption of oxygen, resulting in the TPZ encapsulated in the aqueous liposome chamber brings out TPZ radicals to cause DNA double-strand breaks and chromosome aberrations. In vivo studies demonstrated that the liposomes which encapsulate IR780 and TPZ showed great antitumor efficacy via combining photodynamic therapy with chemotherapy. Therefore, the investigation combines PDT and hypoxia-activated chemotherapy from the TPZ. It is a simple but effective liposome platform to achieve multiple synergistic antitumor efficacy and shows potential for clinical use.