Review of Metal–Polyphenol Self-Assembled Nanoparticles: Synthesis, Properties, and Biological Applications in Inflammatory Diseases

Polyphenols, which are compounds characterized by the presence of phenolic hydroxyl groups, are abundantly found in natural plants and exist in highly complex forms within living organisms. As some of the most prevalent compounds in nature, polyphenols possess significant medicinal value due to their unique structural features, particularly their therapeutic efficacy in antitumor, anti-inflammatory, and antibacterial applications. In the context of inflammation therapy, polyphenolic compounds can inhibit the excessive release of inflammatory mediators from inflammatory cells, thereby mitigating inflammation. Furthermore, these compounds exhibit strong antioxidant properties, enabling them to scavenge free radicals and reactive oxygen species (ROS), reduce oxidative stress-related damage, and exert anti-inflammatory effects. Due to their multiple phenolic hydroxyl groups and their ability to chelate various metals, polyphenols are extensively utilized in the synthesis of self-assembled nanoparticles for the treatment of various diseases. Numerous studies have demonstrated that the therapeutic profile of nanoparticles formed through self-assembly with metal ions surpasses that of polyphenolic compounds alone. This Review will focus on the self-assembly of different polyphenolic compounds with various metal ions to generate nanoparticles, their characterization, and their therapeutic applications in inflammation-related diseases, providing researchers with new insights into the synthetic study of metal-polyphenol nanocomposites and their biological applications.