Equal volume impregnation–air calcination synthesis of lithium-doped MgO nanoplates for enhanced antibacterial performance†

Abstract

Magnesium oxide nanomaterials (nano-MgO) have many advantages, such as environmentally benign, high thermal stability, no need of illumination, broad-spectrum antibacterial activity and more. However, its low activity has restricted the application in environmental purification and antibacterial disinfection. Herein, the equal volume impregnation–air calcination method was first used in the synthesis of nano-MgO and a series of nano-MgO with varying amounts of Li doping were prepared to enhance their antibacterial properties. Li doping leads to the distortion of MgO lattice structure and the presence of oxygen vacancies, enhancing oxygen absorption and alkalinity. This enhancement effectively promotes the formation of reactive oxygen species (ROS) and maintains its high chemical reactivity. The Li doped nano-MgO at 100 μg mL⁻¹ showed a significant improvement in antibacterial activity, achieving the antibacterial ratio of 99.6% against Escherichia coli (E. coli). Moreover, the contribution of alkalinity, ROS, physical morphology effect, and dissolved ions (Mg²⁺ and Li⁺) to the antibacterial ability was further discussed. Especially, the results of dialysis tube test indirectly indicated that ROS played the crucial role in enhancing the antibacterial performance of nano-MgO. This study lays an essential foundation for further investigation into the antibacterial performance and mechanism of nano-MgO.