This book is very important in view point of biological aspects. In this book author has discussed about the use of metal nanoparticles for anti microbial, biological and catalytic activities. Author has successfully synthesized copper nanoparticles in side a system (P(NIPAM-co-AAA) microgel, which enhances the activity of the said metal nanoparticles. The activities of nanoparticles enhances due to increase in surface area and their stability.