Metal hexacyanoferrates in photodynamic and photothermal therapies

Photodynamic therapy (PDT) involves a reaction between photosensitizers (PS) and oxygen (O₂) to generate cytotoxic reactive oxygen species (ROS), which effectively eliminate undesired cells. Compared to conventional treatments like surgery, radiation, and chemotherapy, PDT offers several advantages, including minimal toxicity to healthy tissues and no long-term systemic side effects. However, its therapeutic efficacy is limited under hypoxic conditions, as the process relies on the presence of oxygen in the target tissue. To address these challenges, combining PDT with photothermal therapy (PTT) creates a synergistic phototherapy approach. The heat generated by PTT enhances blood flow in tumors, increasing oxygen delivery to tumor sites and boosting PDT's effectiveness. These combinations are being explored in PDT/PTT as an innovative, synergistic cancer treatment strategy, aiming to enhance the therapeutic index. One promising strategy to connect both PDT and PTT therapies involves developing nanosystems that integrate metal hexacyanoferrate (MHCF) nanoparticles with multifunctional PS. Here, we review several studies that have evaluated the combination of MHCF with various PSs to apply PDT and PTT synergistically. We discuss how nanocomposites based on these materials can address the challenges and limitations still faced in PDT/PTT. This review aims to identify new opportunities for the application of metal hexacyanoferrates in these phototherapeutic modalities.