Abstract
Metastatic melanoma cancer stem cells are subpopulations that have been identified and
linked to tumor progression, immunoevasive behavior, drug resistance, and metastasis, leading to a
poor prognosis. Photodynamic therapy (PDT) is an approach to eradicate cancer through a photochemical
process which directly generates reactive oxygen species (ROS). This study investigated the
impact of PDT using an aluminum phthalocyanine gold nanoparticle (AlPcS4Cl-AuNP) conjugate for
targeting melanoma stem cells. The isolated stem cells were irradiated at 673.2 nm with a radiant
exposure of 5 J/cm2. Post-irradiation signs of cell death were determined using microscopy and
biochemical assays. A possible enhanced effect of ROS in inducing cell death could be seen when
AlPcS4Cl was conjugated to AuNPs. Nanoparticles as carriers promote the efficient cellular uptake
of photosensitizers, enhancing organelle accumulation and the targeted therapy of cancerous cells.
A biochemical assay revealed significant post-irradiation signs of cell death. The measurement of
adenosine triphosphate (ATP) content revealed a decrease in cell proliferation. The study suggested
an approach directed at expanding the knowledge on PDT to improve cancer treatment. Understanding
the cell death mechanism through which ROS influence cancer stem cells (CSCs) is, therefore,
useful for improving PDT efficiency and preventing tumor recurrence and metastasis.