Advances in Plant-Mediated ZnO Nanoparticles: Synthesis Mechanisms, Functional Applications, and Environmental Implications-A Review

Scientists are increasingly drawn to zinc oxide nanoparticles because of their exceptional properties and broad range of potential applications. A variety of physical and chemical methods are employed for the synthesis of ZnO nanoparticles. Over time, these methods exert adverse effects on the environment due to their reliance on hazardous chemicals and energy-intensive processes; consequently, green synthesis has emerged as a more environmentally sustainable alternative.Green synthesis utilizes natural sources including microorganisms, fungi, algae, and different plant parts such as roots, leaves, flowers, seeds, and fruits. The phytochemicals found in green sources like phenols, flavonoids, terpenes, and alkaloids reduces (Zn²⁺ to Zn) and also help to stabilise the metal ions, which reduces the need for synthetic additions. To get the idea about the morphology, shape, nanoparticle size, crystal structure, elemental composition of synthesized NPs various characterization techniques can be used such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) enable researchers to better understand the behaviour and development of these nanoparticles. ZnO nanoparticles have shown a wide range of applications, including use as photocatalysts and as antimicrobial, antioxidant, antidiabetic, and anticancer agents, as well as in various biomedical applications. However, recent studies have raised concerns regarding their potential toxicity, emphasizing the need for further research to fully elucidate their biological effects.These NPs are toxic for water bodies and affect our ecosystem, even enter in human bodies and cause severe diseases like cancer. In light of the field's ongoing development, this review highlights the need to address safety and toxicity while summarising current knowledge on the green synthesis of ZnO NPs using plant-based methods and exploring their various applications.