143 © Springer Nature Singapore Pte Ltd. 2018 S. K. Gahlawat et al. (eds.), Advances in Animal Biotechnology and its Applications, https://doi.org/10.1007/978-981-10-4702-2_9 P. Jamdagni · P. K. Sidhu · P. Khatri · K. Nehra (*) · J. S. Rana Department of Biotechnology, Deenbandhu Chhotu Ram University of Science & Technology, Murthal, Sonipat 131039, Haryana, India 9 Metallic Nanoparticles: Potential Antimicrobial and Therapeutic Agents Pragati Jamdagni, Parveen Kaur Sidhu, Poonam Khatri, Kiran Nehra, and J. S. Rana 9.1 Introduction As the year 1959 approached its ending, Nobel Laureate Richard Feynman marked the beginning of a new era in the ield of science with his lecture entitled “There’s Plenty of Room at the Bottom,” which he delivered at the American Physical Society at the California Institute of Technology. The lecture had a subtitle stating “An invi- tation to enter a new ield of physics” (Feynman 1960). However, the series of events that followed were no longer exclusive to physics but engulfed almost every branch of science. One such event was the emergence of a new ield in science, “nanotechnology.” In the year 1974, Norio Taniguchi irst coined the term “nano- technology” combining the ultraine size dimensions of nanometers with technol- ogy. Nanometer (nm) refers to the billionth part of a meter, i.e., 10 −9  m, and the science dealing with particles or structures of this size is what we call nanotechnol- ogy (Taniguchi 1974). Moving on, another Nobel laureate Richard Smalley (1992) stated that “the impact of nanotechnology on health, wealth, and the standard of living for people will be at least the equivalent of the combined inluences of micro- electronics, medical imaging, computer-aided engineering, and man-made poly- mers in this century” (Mnyusiwalla et al. 2003). Since then, nanotechnology has become one of the most important, interesting, and rapidly expanding ields existing as the fusion product of various ields such as physics, chemistry, biology, engineer- ing, etc. In terms of its applications in medicine and therapeutics, nanostructures are well researched owing to their unique behavior as compared to their bulk counterparts. Medical professionals all over the world are facing major challenges in the ield of microbial infections. While timely and correct diagnosis is one of the issues, the development of resistance in pathogenic bacteria and fungi against routinely used