pH-responsive -zinc oxide-protoporphyrin IX nanoconjugates with enhanced cellular uptake for photodynamic therapy towards cancer cells.

Photodynamic therapy (PDT) of cancer has been limited by the poor solubility of most photosensitizers, use of high drug dosages, and the pH difference between the tumor tissue microenvironment (slightly acidic) and the bloodstream. These affect cellular uptake, selectivity and singlet oxygen generation. We formulated -green synthesized zinc oxide-protoporphyrin IX (PG-ZnO-PP) nanoconjugates by conjugating the ZnO nanoparticles enriched with amino groups and PP. PG-ZnO-PP nanoconjugates showed higher rate of reactive oxygen species generation, improved cellular uptake in the acidic pH and lower IC toward Eca-109 cells for PDT. PG-ZnO-PP nanoconjugates are a potential solution to reducing drug dosage of PP through improved drug uptake, for enhanced targetability and reduced skin photosensitivity with improved PDT efficacy.