ZnO nanoparticles via <i>Sutherlandia frutescens</i> plant extract: physical and biological properties

Abstract

The quest for eco-friendly synthetic routes for the development of multifunctional nanoparticles for biomedical applications has reinforced the use of plant extracts as replacement solvents. Amongst the various nanoparticles, ZnO nanoparticles have emerged as a preferred candidate for various biological applications. In this study, ZnO nanoparticles were successfully synthesized by the solvothermal method using Sutherlandia frutescens extract. The morphological, structural, functional properties, elemental mapping and mass to charge ratio analysis were confirmed by TEM, SEM, SAED, FTIR, EDS and LCMS techniques. The ZnO nanoparticles exhibited a spherical morphology with a particle size distribution ranging from 5–25 nm. FTIR corroborated the formation of these nanoparticles with the ZnO peak identified in the fingerprint region. FTIR further showed the introduction of the phytochemical functional groups found in plants that were also confirmed on the Sf ZnO nanoparticles. The presence of bioactive molecules extracted from the plants were tested using wet chemistry and identified by LCMS. EDS analysis exhibited strong ZnO peaks which were verified by their elemental mapping using the same technique. Sf ZnO nanoparticles displayed exceptional biomedical activity with an antiproliferative effect of 93% against human lung cancer cells (A549) owing to the phytochemicals obtained from the Sutherlandia frutescens plant extract. These nanoparticles were also potent against gram-negative (Escherichia coli, Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus, Enterobacter faecalis) strains using model pollutants and real water pollutants.