Green Synthesis of Nanoparticles Using Medicinal Plant Extracts: Principles, Mechanisms, Characterization, and Their Biological Activity

The green synthesis of nanoparticles is a new eco-friendly, cost-efficient and sustainable method in nanotechnology. The use of plants to synthesize nanoparticles has been gaining traction in the field of green synthesis due to the presence of a wide variety of bioactive phytochemicals such as flavonoids, alkaloids, terpenoids, phenolic compounds, tannins, and proteins that can act as reducing, capping, and stabilizing agents. Depending on the materials or synthesis conditions, plant-mediated synthesis can decrease the use of hazardous chemicals, reduce environmental impacts, and enhance the biocompatibility of the nanomaterials produced, compared with conventional physical and chemical synthesis methods. The plant derived nanotechnology has shown great promise in biomedical and pharmaceutical applications such as antimicrobial, antioxidant, anticancer, anti-inflammatory, wound healing, drug delivery, antiviral and diagnostic applications. They are affected by various factors such as plant species, the composition of extracts, the concentration of their precursors, the pH, temperature, reaction time and synthesis conditions. For this reason, characterisation is crucial to define their structural, morphological, optical, chemical, biological performance and safety. The essential principles and mechanisms of plant mediated synthesis of nanoparticles, major preparation methods, characterization techniques and the factors that affect the synthesis of nanoparticles by plants are discussed. It also explores the benefits and drawbacks of green synthesis, the medicinal uses of plant-based nanomaterials and the latest developments in their biomedical applications. Last, emerging opportunities, current challenges and future research directions are emphasized to facilitate the development of safe, reproducible and scalable green nanotechnology.