This textbook for graduate and postgraduate students provides comprehensive applications of nanoparticles in medicine, agriculture, and environmental sciences. The initial chapter covers basic topics related to types, synthesis, structure, and properties of various nanoparticles. It further discusses the wide range of applications of nanoparticles in medicine, agriculture, and the environment. The book presents nano-electronic biosensors that are used to diagnose and monitor the progression of human diseases. It summarizes the opportunities and challenges of nanotechnology in the agriculture and food sector highlighting the scientific, technical, regulatory, safety, and societal impacts.