The preparation of gold nanoparticles (AuNPs) involves a variety of chemical and physical
methods. These methods use toxic and environmentally harmful chemicals. Consequently, the
synthesis of AuNPs using green chemistry has been under investigation to develop eco-friendly
nanoparticles. One approach to achieve this is the use of plant-derived phytochemicals that are
capable of reducing gold ions to produce AuNPs. The aim of this study was to implement a
facile microtitre-plate method to screen a large number of aqueous plant extracts to determine
the optimum concentration (OC) for the bio-synthesis of the AuNPs. Several AuNPs of different
sizes and shapes were successfully synthesized and characterized from 17 South African plants.
The characterization was done using Ultra Violet-Visible Spectroscopy, Dynamic Light Scattering,
High Resolution Transmission Electron Microscopy and Energy-Dispersive X-ray Spectroscopy.
We also studied the effects of temperature on the synthesis of the AuNPs and showed that changes in
temperatures affect the size and dispersity of the generated AuNPs. We also evaluated the stability of
the synthesized AuNPs and showed that some of them are stable in biological buffer solutions.