Another application of biogenic substances is in the synthesis of metallic nanoparticles. The current chemical and physical production methods for nanoparticles used are costly and produce toxic waste and pollutants in the environment. Additionally, the nanoparticles that are produced can be unstable and unfit for use in the body. Using plant-derived biogenic substances aims to create an environmentally-friendly and cost-effective production method. The biogenic phytochemicals used for these reduction reactions can be derived from plants in numerous ways, including a boiled leaf broth, biomass powder, whole plant immersion in solution, or fruit and vegetable juice extracts. C. annuum juices have been shown to produce Ag nanoparticles at room temperature when treated with silver ions and additionally deliver essential vitamins and amino acids when consumed, making them a potential nanomaterials agent. Another procedure is through the use of a different biogenic substance: the exudate of germinating seeds. When seeds are soaked, they passively release phytochemicals into the surrounding water, which after reaching equilibrium can be mixed with metal ions to synthesise metallic nanoparticles. M. sativa exudate in particular has had success in effectively producing Ag metallic particles, while L. culinaris is an effective reactant for manufacturing Au nanoparticles. This process can also be further adjusted by manipulating factors such as pH, temperature, exudate dilution and plant origin to produce different shapes of nanoparticles, including triangles, spheres, rods, and spirals. These biogenic metallic nanoparticles then have applications as catalysts, glass window coatings to insulate heat, in biomedicine, and in biosensor devices.