OICC Press Progress in Biomaterials 2194-0517 9 3 (September 2020) 2020 07 11 Synthesis of silver nanoparticles utilizing various biological systems: mechanisms and applications—a review 10.1007/s40204-020-00135-2 EN Divyanshi Garg Noida Institute of Engineering and Technology, Greater Noida, Uttar Pradesh, IN Aritri Sarkar Noida Institute of Engineering and Technology, Greater Noida, Uttar Pradesh, IN Pooja Chand Noida Institute of Engineering and Technology, Greater Noida, Uttar Pradesh, IN Pulkita Bansal Noida Institute of Engineering and Technology, Greater Noida, Uttar Pradesh, IN Deepak Gola Noida Institute of Engineering and Technology, Greater Noida, Uttar Pradesh, IN Shivangi Sharma Department of Microbiology, Shaheed Rajguru College of Applied Sciences for Women, University of Delhi, Delhi, IN Sukirti Khantwal Department of Microbiology, Shaheed Rajguru College of Applied Sciences for Women, University of Delhi, Delhi, IN Surabhi Department of Microbiology, Shaheed Rajguru College of Applied Sciences for Women, University of Delhi, Delhi, IN Rekha Mehrotra Department of Microbiology, Shaheed Rajguru College of Applied Sciences for Women, University of Delhi, Delhi, IN Nitin Chauhan Department of Microbiology, Shaheed Rajguru College of Applied Sciences for Women, University of Delhi, Delhi, IN Randhir K. Bharti University School of Environmental Management, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi, IN Journal Article 2020 07 11 Abstract The evolving technology of nanoparticle synthesis, especially silver nanoparticle (AgNPs) has already been applied in various fields i.e., electronics, optics, catalysis, food, health and environment. With advancement in research, it is possible to develop nanoparticles of various size, shape, morphology, and surface to volume ratio utilizing biological systems. A number of different agents and methods can be employed to develop choice based AgNPs using algae, plants, fungi and bacteria. The use of plant extracts to produce AgNPs appears to be more convenient, as the method is simple, environmental friendly and inexpensive, also requiring a single-step. The microbial synthesis of AgNps showed intracellular and extracellular mechanisms to reduce metal ions into nanoparticles. Studies have shown that different size (1–100 nm) and shapes (spherical, triangular and hexagonal etc.) of nanoparticles can be produced from various biological routes and these diverse nanoparticles have various functions and usability i.e., agriculture, medical-science, textile, cosmetics and environment protection. The present review provides an overview of various biological systems used for AgNP synthesis, its underlying mechanisms, further highlighting the current research and applications of variable shape and sized AgNPs.