Nanoparticles of methylene blue enhance photodynamic therapy

Schematic representation of the mechanism of action of PDT with nanoparticles in breast cancer cells. In particular, AgNPs induce mitochondrial and DNA damage by ROS. [Display omitted] •Nanoparticles combined to methylene blue have great potential as an agent in PDT.•The cellular uptake of MDA-MB-468 was investigated by fluorescence.•The cytotoxicity effects of AgNPs are the release of Ag+ ions from their surface. Breast cancer is the most commonly diagnosed cancer and the second leading cause of death related to cancer among women worldwide. Screening and advancements in treatment have improved survival rate of women suffering from this ailment. Novel therapeutic techniques may further reduce cancer related mortality. One of several emerging therapeutic options is Photodynamic Therapy (PDT) that uses light activated photosensitizer (PS) inducing cell death by apoptosis and/or necrosis. Nanotechnology has made contribution to improve photosensitizer for PDT, increasing the efficiency of therapy using gold and silver nanoparticles. Efforts have been done to develop better mechanism to improve PS and consequently PDT effects. In this study, we investigate the efficacy of the PDT using gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) when mixed to methylene blue (MB) in the treatment of the human breast adenocarcinoma cell line (MDA-MB-468). The MDA-MB-468 was treated in the presence of different MB concentrations with/without AuNPs or AgNPs. The colloidal solution of AgNPs showed a plasmon resonance band at 411 nm in UV–visible range and a bimodal size distribution. The results of viability analysis showed that cells treated with nanoparticles exhibited higher cytotoxicity than cells treated with only MB, improving the efficiency of the treatment in the tumor cells. The cytotoxicity effect of MB associated with AgNPs on MDA-MB-468 cell line could be related to increased reactive oxygen species production due to the release of Ag+ ions from nanoparticles surface, suggesting that the association between FS and AgNPs has potential as a PDT agent.