An acidic tumor pH-responsive nanophotomedicine (pH-NanoPM) for targeted photodynamic therapy (PDT) was demonstrated herein. The pH-NanoPM was prepared with a size of ~110 nm by self-assembly of a pH-responsive polymeric photosensitizer (pH-PPS) consisting of pH-cleavable methoxypolyethylene glycol (pH-C-mPEG). Because the pH-C-mPEG can be detached from the nanoparticles by hydrolysis of the benzoic-imine group at the pH of an acidic tumor (~6.5), the particle size and surface charge of the pH-NanoPM were changed along with the environmental pH condition. After detachment of the pH-C-mPEG, the pH-NanoPM particles became positively charged (+18.67±1.95 mV) due to exposure of primary amine groups and decreased to a size of ~40 nm. Fromin vitrocellular experiments with HeLa human cervical cancer cells, the pH-NanoPM exhibited enhanced cellular internalization at acidic tumor pH compared to normal pH, which led to a significant cancer cell killing effect. These results suggest that this system has the potential to be used as a new class of nanophotomedicine for targeted photodynamic cancer therapy.
Tumor pH-responsive flower-like micelles of poly(l-lactic acid)-b-poly(ethylene glycol)-b-poly(l-histidine)