Self-assembly of nanoparticles by human serum albumin and photosensitizer for targeted near-infrared emission fluorescence imaging and effective phototherapy of cancer.

Photodynamic therapy (PDT) and photothermal therapy (PTT) are effective cancer treatments, and photosensitizers play the most important role in the treatment. However, photosensitizers are insufficient for in vivo tumor treatment. Herein, we develop a small molecule fluorophore Cy-HPT as a novel photosensitizer, which possesses the advantages of near-infrared (NIR) emission, high photothermal conversion efficiency and high singlet oxygen generation efficiency. Moreover, a nanoplatform of HSA@Cy-HPT was synthesized by self-assembly of Cy-HPT and human serum albumin (HSA) in aqueous solution. Compared to Cy-HPT, HSA@Cy-HPT possesses more stable spectral properties, enhances the effect of PDT/PTT, and exhibits more satisfactory in vivo metabolism. HSA@Cy-HPT demonstrates outstanding tumor targeting in subcutaneous tumor xenograft models owing to its enhanced permeability and retention in tumor tissue. Furthermore, HSA@Cy-HPT was successfully utilized in tumor xenograft models and tumor tissue growth was clearly inhibited without any regrowth, extending survival rate of the models. Also, no distinct damage of the normal tissue of tumor xenograft models was observed using hematoxylin & eosin staining. This study presents a promising therapeutic agent for the synergetic PDT and PTT cancer treatment.