## 1 Introduction
#### 2.1.6 Characterisation of AgNPs  
UV-visible spectroscopy  
AgNP synthesis was determined by examining each colloidal solution (1 mL) after synthesis using the SHIMADZU UV-1800 Spectrophotometer (Cole-Parmer, Duisburg, Germany) at a range of 200-800 nm at a medium speed, using 1 mM AgNO\({}_{3}\) solution as a blank. The absorption spectra for each sample were correlated to that found in the literature, confirming their successful synthesis. Prior to analysis, all synthesized samples were sonicated (SONICLEAN, Australia sonication bath) and vortexed for 5 min in order to ensure uniformity of the solution.  
Ultra Plus field emission gun Scanning electron microscopy (SEM)  
Approximately 2 mL of each synthesized NP solution was pipetted separately into 3 mL Eppendorf Tubes\({}^{\text{\textregistered}}\) and sonicated (SONICLEAN, sonication bath) for 20 min. Thereafter, approximately 20 \(\mu\)L of each solution was pipetted onto aluminium stubs and left to dry for 60 min beneath a mercury lamp. The stubs were sputter coated with gold using the Quorum 150 RES. Samples were viewed and analyzed on an Ultra Plus field emission gun scanning electron microscope (FEGSEM) (Carl Zeiss, Jena Germany). Images were captured using the SmartSEM imaging software 8.0.  
Energy-dispersive X-ray spectroscopy (EDX)  
Energy dispersive X-ray spectroscopy analytically detects elemental compositions present in any material. The synthesized NP solutions of the leaves and stems were sonicated (SONICLEAN, sonication bath) for 20 min. Thereafter, approximately 20 \(\mu\)L of each solution was dispensed onto a glass coverslip attached to an aluminium stub containing double-sided adhesive carbon tape. Solutions were dried under a mercury lamp for about 60 min. The elemental composition of the NPs produced from the leaf and stem-methanolic extracts were identified using the Aztec analysis software 1.2 on the Ultra Plus FESEM (Carl Zeiss, Germany) at 5 kV.  
High-resolution transmission electron microscopy (HRTEM)  
The shape, size, and distribution of the synthesized AgNPs produced from leaves and stems were analysed with the HRTEM. Each solution was sonicated (SONICLEAN, sonication bath) to ensure that the AgNPs were evenly distributed. Formvar carbon coated grids (400-mesh) (Ted Pella Inc., Redding, CA, USA) were dipped in each solution and placed under a lamp for 1 h at room temperature to allow the solvent to evaporate. Samples were viewed under the JEOL JEM HRTEM 2100 (Tokyo, Japan) at 200 kV. Image) software Java 1.53e was used to determine the size of the AgNPs.  
Nanoparticle Tracking Analysis (NTA)  
To precisely elucidate the zeta potential, size distribution, and nano-complexes of all synthesized AgNPs, NTA (Nanosight NS-500, Malvern Instruments, UK) was conducted at a temperature of 25 \({}^{\circ}\)C. Approximately 2 mL of each nanoparticle solution (methanolic, aqueous-fresh, and aqueous-powdered AgNPs) was extracted and transferred into Eppendor tubes (3 mL). A dilution of 1 mL at a ratio of 1:500 (in 18 Mohm water/Ultrapure Millipore water) of each extract was prepared in suspension for analysis, aimed at determining the hydrodynamic diameter. All samples underwent triplicate analyses. Images were viewed, captured, and evaluated using the NTA 3.2 analytical software.  
Fourier transform infrared spectroscopy (FTIR)  
In order confirm the presence of capping functional groups in the AgNPs, infrared spectroscopy of the dried leaf and stem extracts and their synthesized AgNPs was achieved using the Agilent Cary 630 spectrometer using Agilent MicroLab PC 5.1.22. Resolution Pro 5.0.0.395 was used to process the data for peaks. The data were collected using ATR Diamond\({}^{-1}\) Bounce with 30 background scans and 30 sampling scans with a resolution of 4 cm\({}^{-1}\). The detection of peaks displayed by the various function groups were scanned at a range between 3800-800 cm\({}^{-1}\).