Porphyrin/metalloporphyrin and their conjugates: a promising platform for drug delivery

Porphyrins and metalloporphyrins are emerging as versatile platforms for advanced drug delivery due to their unique structural, photophysical, and coordination properties. These macrocyclic compounds, known for their chemical stability and capacity to chelate various metal ions, address critical challenges in drug delivery, including poor solubility, non-specific toxicity, and limited control over drug release. This review explores synthetic strategies for porphyrins and their metal complexes, including classical and green methods, and highlights their therapeutic applications through diverse nanocarrier systems, such as gold nanoparticles, cyclodextrin conjugates, mesoporous silica, liposomes, and metal-organic frameworks. These systems offer stimuli-responsive, targeted, and synergistic therapeutic functionalities-especially in cancer therapy-by combining chemotherapy with photodynamic or sonodynamic modalities. Despite their promise, limitations persist, including scalability issues, potential metal toxicity, and insufficient long-term biocompatibility data. The review outlines future directions, advocating for AI-driven design, sustainable synthesis, and expanded applications beyond oncology, emphasizing the need for systematic comparative studies and clinical translation efforts.