Silver nanoparticles (AgNPs) have been widely used in biomedical fields because of their intrinsic therapeutic properties. Here, we introduce methods of synthesizing AgNPs and discuss their physicochemical, localized surface plasmon resonance (LSPR) and toxicity properties. We also review the impact of AgNPs on human health and the environment along with the underlying mechanisms. More importantly, we highlight the newly emerging applications of AgNPs as antiviral agents, photosensitizers and/or radiosensitizers, and anticancer therapeutic agents in the treatment of leukemia, breast cancer, hepatocellular carcinoma, lung cancer, and skin and/or oral carcinoma.

A novel, low-cost and direct green synthesis strategy was developed for the preparation of polymer composite spheres composed of silver nanoparticles (AgNPs) decorated on the polymer colloids in a raspberry-like fashion. The polymer colloids were employed as both the reductant and the substrate support. The environmentally benign reaction system consists of AgNO3, polymer spheres and an ethanol solvent, without any additional reducing agents or stabilizers. The obtained composite spheres are surprisingly stable. The size range of the formed AgNPs is from several to tens of nanometers, dependent on the reaction time, AgNO3 concentration, and the amount of polymer spheres. A four-step mechanism was proposed for the formation of AgNPs-coated polymer spheres emphasizing the role of ethanol for saturating the external surface of the polymer spheres first. These composites exhibit excellent antibacterial activity, which is dependent on both the concentration of the composite spheres and the size of coated AgNPs.