A Review of the Green Synthesis of ZnO Nanoparticles Utilising Southern African Indigenous Medicinal Plants

Abstract

Metal oxide nanoparticles (NPs), such as zinc oxide (ZnO), have been researched extensively for applications in biotechnology, photovoltaics, photocatalysis, sensors, cosmetics, and pharmaceuticals due to their unique properties at the nanoscale. ZnO NPs have been fabricated using conventional physical and chemical processes, but these techniques are limited due to the use of hazardous chemicals that are bad for the environment and high energy consumption. Plant-mediated synthesis of ZnO NPs has piqued the interest of researchers owing to secondary metabolites found in plants that can reduce Zn precursors and stabilise ZnO NPs. Thus, plant-mediated synthesis of ZnO NPs has become one of the alternative green synthesis routes for the fabrication of ZnO NPs. This is attributable to its environmental friendliness, simplicity, and the potential for industrial-scale expansion. Southern Africa is home to a large and diverse indigenous medicinal plant population. However, the use of these indigenous medicinal plants for the preparation of ZnO NPs is understudied. This review looks at the indigenous medicinal plants of southern Africa that have been used to synthesise ZnO NPs for a variety of applications. In conclusion, there is a need for more exploration of southern African indigenous plants for green synthesis of ZnO NPs.

Biosynthesis and antibacterial activity of ZnO nanoparticles using Buchanania obovata fruit extract and the eutectic-based ionic liquid

“…In the eutectic-based ionic liquid case the majority of the ZnO NPs exhibit uniform size, no agglomeration, with only a few larger particles present, showcasing significant size homogeneity in the synthesized NPs. While, in the fruit extract medium the agglomeration of ZnO NPs is apparent, a common occurrence in the plant-mediated green synthesis NPs [93]. Agglomeration arises when NPs cluster during synthesis or sample preparation, potentially impacting NPs dispersion, reactivity, and toxicity [94].…”

Antioxidant and Anti-inflammatory Applications of Aerva persica Aqueous-Root Extract-Mediated Synthesis of ZnO Nanoparticles

“…When compared to other metal oxide nanoparticles, ZnO NPs have outstanding biomedical applications such as anticancer, drug delivery, diabetic treatment, wound healing, anti-inflammation, antibacterial, and antioxidant. − Based on earlier reports different plant-extract-mediated methodologies have been developed for the synthesis of ZnO nanoparticles using extracts from different components like leaves, bark, shoots, and roots of a plant . Several researchers have employed these plant-extract-mediated synthesized ZnO nanoparticles as improved antioxidant, antiinflammation, and anticancer agents. − …”

“… 19 Several researchers have employed these plant-extract-mediated synthesized ZnO nanoparticles as improved antioxidant, antiinflammation, and anticancer agents. 25 − 29 …”

Structural, morphological, optical and biomedical applications of Berberis aristata mediated ZnO and Ag-ZnO nanoparticles

“…Zinc oxide (ZnO) nanoparticles (NPs) are one of the well-known nanomaterials because of their outstanding chemical stability, non-toxicity, and cost-effectiveness. They have a wide range of applications in fields like agriculture, environmental remediation, biomedicine, and biosensing [4,5]. Due to their photostability, the higher band gap of 3.37 eV, and significant exciton binding energy of 60 MeV, the material exhibits favourable characteristics [6,7].…”