Plant-Based Extracts as Reducing, Capping, and Stabilizing Agents for the Green Synthesis of Inorganic Nanoparticles

The synthesis of inorganic nanoparticles for diverse applications is an active research area that involves physical and chemical methods, which typically are expensive, involve hazardous chemical reagents, use complex equipment and synthesis conditions, and consume large amounts of time and energy. Thus, green synthesis methods have emerged as eco-friendly and easy alternatives for inorganic nanoparticle synthesis, particularly the use of plant-based extracts from fruit juice, leaves, seeds, peel, stem, barks, and roots, which act as reducing, capping, and stabilizing agents, contributing to the Sustainable Development Goals and circular economy principles. Therefore, diverse inorganic nanoparticles have been synthesized using plant-based extracts, including gold, silver, titanium dioxide, zinc, copper, platinum, zirconium, iron, selenium, magnesium, nickel, sulfur, cobalt, palladium, and indium nanoparticles, which exhibit different biological activities such as antioxidant, antimicrobial, dye degradation, cytotoxic, analgesic, sedative, wound-healing, skin protection, sensor development, and plant-growth-promoting effects. Therefore, this review summarizes the advantages and limitations of plant-based extracts as reducing, capping, and stabilizing agents for inorganic nanoparticle green synthesis.