Targeted Photosynthetic Nanoparticle Drug Delivery System for Enhanced Photodynamic Therapy Treatment of Metastatic Melanoma

Metastatic melanoma is the 6th most common cancer diagnosed worldwide, with approximately 100 000 annual related deaths. Photodynamic therapy (PDT) is a photochemotherapeutic cancer treatment that utilizes a photosensitizer (PS) drug that, when activated by laser light at a specific wavelength, yields reactive oxygen species (ROS), which in turn induces cell death. However, due to the passive diffusion of PSs, normal surrounding cells are sometimes affected and their targeted concentrations in cancer cells tends to be minimal, thus limiting the effectiveness of this treatment. Therefore a multicomponent drug targeting strategy is often applied to improve PS specific delivery and concentration in cancer cells only, which in turn can improve the effectiveness of PDT. Thus the intention of this study was to improve the photosynthetic drug delivery of Zinc Phthalocyanine Tetrasulphonic acid (ZnPcS4) in metastatic melanoma cells, by enhancing its chemical structure. ZnPcS4 was successfully conjugated to pegylated gold nanoparticles in order to maximize its solubility and stability, as well as bound to active tumour-associated antibody-antigens (anti-MIA) to aid in specific targeted PS delivery. In in vitro cultured metastatic melanoma (A375) cells, this molecular drug conjugate proved to have enhanced cellular uptake within the cancer cells. Furthermore, after conducting in vitro PDT experiments with A375 cells, a significant amount of cell death and cytotoxicity was noted. Overall, this molecular drug conjugation combination of ZnPcS4 with AuNP and anti-MIA, proved to enhance the treatment capabilities of PDT for this form of cancer.