Salvianolic acid B as a potent nano‐agent for enhanced ALA‐PDT of oral cancer and leukoplakia cells

Abstract Background Photodynamic therapy (PDT) relies on the light activation of a photosensitizers to generate reactive oxygen species such as singlet oxygen, but its effect on cancer therapy is limited dramatically by hypoxia in the tumor microenvironment. Objectives To determine the potential of a nano‐photosensitizer loaded salvianolic acid B (SalB) and 5‐aminolevulinic acid (ALA) for enhancing the efficacy of PDT in oral squamous cell carcinoma Cal27 cells and leukoplakia Leuk1 cells. Results Singlet oxygen sensor green (SOSG) assay showed that nano‐SalB‐ALA generated higher levels of singlet oxygen, compared to nano‐SalB and nano‐ALA. Cellular uptake assay showed that nano‐SalB‐ALA effectively absorbed by Leuk1 cells. Importantly, cell counting kit‐8 and flow cytometry revealed that PDT with nano‐SalB‐ALA effectively inhibited the viability and induced the apoptosis of Cal27 and Leuk1 cells, respectively. Moreover, the tumor xenograft study revealed that PDT with nano‐SalB‐ALA had a stronger inhibitory effect on tumor growth of nude mice, compared to control groups. Conclusions The novel photosensitizer nano‐SalB‐ALA remarkably enhanced the efficacy of PDT by improving singlet oxygen production, inhibiting cell proliferation, promoting cell apoptosis, and suppressing tumor growth. These suggest PDT with nano‐SalB‐ALA could be a clinically significant and potent treatment for oral cancer and leukoplakia.