Metal-Free Nanoassemblies of Water-Soluble Photosensitizer and Adenosine Triphosphate for Efficient and Precise Photodynamic Cancer Therapy.

Engineering photosensitizers into stimuli-responsive supramolecular nanodrugs allows enhanced spatiotemporal delivery and controllable release of photosensitizers, which is promising for dedicated and precise tumor photodynamic therapy. Complicated fabrication for nanodrugs with good tumor accumulation capability and the undesirable side-effects caused by the drug components retards the application of PDT in vivo. The fact that extracellular adenosine triphosphate (ATP) is overexpressed in tumor tissue has been overlooked in fabricating nanomedicines for tumor-targeting delivery. Hence, herein we present metal-free helical nanofibers formed in aqueous solution from the coassembly of a cationic porphyrin and ATP as a nanodrug for PDT. The easily accessible and compatible materials and simple preparation enable the nanodrugs with potential in PDT for cancer. Compared to the cationic porphyrin alone, the porphyrin-ATP nanofibers exhibited enhanced tumor-site photosensitizer delivery through whole-body blood circulation. Overexpressed extracellular ATP stabilizes the porphyrin-ATP nanodrug within tumor tissue, giving rise to enhanced uptake of the nanodrug by cancer cells. The enzyme-triggered release of photosensitizers from the nanodrugs upon biodegradation of ATP by intracellular phosphatases results in good tumor therapeutic efficacy. This study demonstrates the potential for employing the tumor microenvironment to aid the accumulation of nanodrugs in tumors, inspiring the fabrication of smart nanomedicines.