This book explores the green synthesis and structural characterization of selenium nanoparticles using Moringa peregrina leaf extract revealing their potent anticancer antioxidant and antibacterial properties. Dr. Samer Y. Al-Qaraleh presents a compelling fusion of nanotechnology and plant-based science supported by advanced analytical techniques (UV-Vis FTIR XRD SEM TEM). Bridging sustainable innovation and biomedical potential this work offers fresh insight into eco-friendly approaches to modern therapeutic challenges.