Recently, plant-mediated route or green approach for preparing metal and metal oxide nanoparticles has received enormous attention due to the ease of preparation and environmental friendliness when compared to physical and chemical methods. Plants contain phytochemicals which have been proposed as bio-reductants and capping agents for forming metal nanoparticles. Therefore, this study was aimed to prepare magnesium oxide nanoparticles (MgONPs) using aqueous extract of Manihot esculenta leaf. The leaf extract was first analyzed in a gas chromatograph–mass spectrometer (GC–MS) to examine the phytochemicals present. Then, the MgONPs formed were evaluated using UV–Visible (UV–Vis) spectrophotometry, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Fourier transform infrared (FTIR) spectroscopy, to confirm the formation of MgONPs and to determine the morphology, elemental composition, shape and size, phase composition and nature of bonds present in the sample. Results revealed the formation of monodisperse, hexagonal shaped MgONPs of average size 36.7 nm having potentials for application in catalysis and as antimicrobial agent. Hence the process reported herein could be optimized for large-scale preparation of MgONPs.

Artificial bone graft materials formed from wollastonite have been extensively used in bone repair because of their high degree of bioactivity and biocompatibility, thereby justifying the development of a protocol for large-scale production. This work reports a novel route for preparing wollastonite via the sol-gel process using bentonite clay as a cheap silica source. The obtained wollastonite was characterized for morphology, elemental composition, phase composition and bioactivity using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and Fourier transform infrared spectroscopy. Results obtained revealed that wollastonite phase was successfully formed in the material and it showed ability to induce formation of apatite within 0.5 day in biological fluid, an indicator for bone-bonding capability. Overall, the wollastonite prepared from the bentonite clay exhibited properties comparable to that synthesized from commercially obtained sodium metasilicate. Hence, our synthetic route may be useful for commercial-scale preparation of wollastonite.

The current work investigated the green and low-cost preparation of silver nanoparticles (AgNPs) using the aqueous extract from Launaea taraxacifolia leaf and studied its antimicrobial effects. The leaf extract was analysed in a gas chromatogram–mass spectrometer to assess the phytochemicals present. UV–Vis spectrophotometer was used to monitor the formation of AgNPs, the morphological assessment was performed by a scanning electron microscope, energy dispersive X-ray analysis was used to determine the elemental composition, the particle size and shape were studied using transmission electron microscopy, and the vibrational modes of bonds in the AgNPs were assessed by Fourier transformed infrared spectroscopy. The AgNPs produced were spherical and in a size range of 9–15.5 nm, monodispersed with a large surface area. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the AgNPs against Pseudomonas aeruginosa and Proteus mirabilis were very low. Against P. aeruginosa, the MIC was 0.10 mg/mL and the MBC was 0.15 mg/mL, while the MIC and MBC against P. mirabilis were 0.05 and 0.25 mg/mL, respectively. Therefore, the AgNPs prepared using L. taraxacifolia leaf extract showed high antibacterial activities and could be a candidate antimicrobial agent for biomedical applications.

Plant-mediated routes for synthesising metal oxide nanoparticles are gaining tremendous attention due to the benefits of the technique: simplicity, cost-effectiveness, and eco-friendliness. We compared the properties of zinc oxide nanoparticles (ZnONPs) made from aqueous leaf extracts of Chromolaena odorata and Manihot esculenta, both of which are abundant on the African continent. The phytochemical composition of the extracts was first assessed using gas chromatography-mass spectrometry (GC-MS) to determine the types of biomolecules involved in the reducing and capping processes that result in ZnONP formation. After that, UV-Vis spectrophotometry, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, X-ray diffractometry, and Fourier transform infrared spectroscopy (FTIR) were used to study ZnONP formation, morphological characteristics, elemental composition, shape and size properties, and phase composition. The ZnONPs made with Chromolaena odorata leaf extract had a better distribution of spherical and hexagonal forms, with an average particle size of 42.35 nm. The ZnONPs made with Manihot esculenta leaf as a reductant had a particle size of 14.71 nm on average and were more agglomerated with poor particle distribution. Phytosterols were shown to be the most important biomolecules in the reduction and capping reactions, according to GC-MS and FTIR analyses. In this study, we created a cost-effective technique for the synthesis of eco-friendly ZnONPs for diverse applications, particularly in Africa, using Chromolaena odorata and Manihot esculenta leaves.Significance: This study could provide useful information on how the phytochemicals embedded in Chromolaena odorata and Manihot esculenta could influence the properties of the ZnONPs obtained from them. Differences in morphology and formation yield of ZnONPs are obtainable from aqueous leaf extracts of Chromolaena odorata and Manihot esculenta. Chromolaena odorata and Manihot esculenta could serve as dependable raw materials for the green synthesis of ZnONPs in Africa.