Dual-agent photodynamic therapy using methylene blue and zinc oxide nanoparticles: sequential illumination enhances apoptotic response in melanoma.

Photodynamic therapy (PDT) is a less disruptive treatment approach that leverages light-sensitive compounds, known as photosensitizers, to generate reactive oxygen species (ROS) upon light activation. These ROS induce cellular damage and apoptosis, making PDT effective against various cancers, including melanoma. Despite its potential, the PDT efficacy against melanoma is often compromised by elements such as melanin pigmentation, which acts as a natural shield against photodynamic effects, and the intrinsic antioxidant defense mechanisms of melanoma cells. This study aims to enhance the efficacy of PDT in melanoma treatment by employing a dual wavelength-assisted approach using Methylene Blue (MB) and zinc oxide nanoparticles (ZnO NPs). A significant decrease in cell viability is noted in the MB + ZnO NPs group, indicating increased cytotoxicity and apoptosis induction. Enhanced production of ROS is seen in melanoma cells treated with MB + ZnO NPs and exposed to dual-wavelength light compared to single-agent treatments. This study demonstrates the potential of dual-wavelength-assisted PDT using MB and ZnO NPs as an effective approach for targeted melanoma treatment.