Green magnesium oxide prepared by plant extracts: synthesis, properties and applications

Green synthesis has gained the interest of the scientific community because it is considered an environmentally friendly process that uses less hazardous chemicals and solvents and does not produce toxic wastes. Magnesium oxide nanoparticles (MgONPs) prepared by green synthesis using plant extracts have emerged as a versatile material for multipurpose applications. Polyphenols are phytochemicals known as natural and renewable reducing, chelating, stabilizing, and precipitating agents, involved in the formation of the MgONPs. In recent decades, there has been an impressive growth in the applications of green MgO, mainly in the areas of materials, biomedical, and environmental areas. Antibacterial, antimicrobial, antioxidant, and anti-cancer activities are promising applications of green MgO in medicine, but also in agriculture. Luminescent properties have been explored for multiple applications in biomedice, sensors. Photodegradation promoted by MgO has also been described for various pollutants. This review addresses the main aspects of MgO synthesis by plant extracts, and it will cover the experimental conditions affecting the formation and properties of MgONPs; the main characterization techniques to assign the magnesium compounds formed; and the most reported applications of MgONPs in environmental, biological, medicinal, and materials science fields. A comprehensive list of plants used so far in the MgO synthesis is presented, as well as the parts of the plants used in the preparation of the extracts. However, more detailed studies are necessary to advance the topic, such as the correlation of the plant extract composition with the MgO properties, quantification of the MgO yield, better characterization and assignment of the magnesium compounds formed in the green synthesis.