It depends on the type of plant and its chemical composition (proteins (amino acids), sugars, enzymes, flavonoids, terpenes, sweeteners, phenolic acids ... ) in order to convert metal ions into nanoparticles.

In plant-mediated nanoparticle synthesis, enzymes such as nitrate reductase and oxidoreductases facilitate the reduction of metal ions, while proteins and amino acids stabilize nanoparticles through interactions with their functional groups. Additionally, phytochemicals—especially phenolics (like tannins and gallic acid), flavonoids (such as quercetin and kaempferol), terpenoids (e.g., limonene), alkaloids, saponins, sugars (like glucose and starch), and organic acids (including ascorbic and citric acids)—function as both reducing and capping agents, with their roles varying across different plant species.