Biogenic Synthesis and Comparative Assessment of the Antimicrobial Activities of Silver and Zinc Nanoparticles of Dialium guineense Leaf Extract against Human Pathogens

Aim: The study aimed to perform a comparative evaluation of the antimicrobial activities of green synthesis of silver and zinc nanoparticles.

Study Design: Experimental.

Methodology: A biogenic and facile method of synthesis of silver and zinc oxide nanoparticles (DGL—SNPs and DGL—ZNPs) using silver nitrate and zinc nitrate as precursors and an aqueous extract of Dialium guineense leaf (DGL) as a reducing agent respectively was demonstrated in this work. The synthesized DGL—SNPs and DGL—ZNPs were checked for their antimicrobial activity against strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, Streptococcus pneumoniae and Candida albicans. Comparative assessment of the antimicrobial activities of DGL—SNPs and DGL—ZNPs against human pathogens were also conducted. Characterization of the metallic nanoparticles were carried out by UV-visible spectroscopy, Fourier transforms infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), powder X-ray diffraction (XRD), Energy dispersive X-ray (EDX), as well as the BET (Brunauer-Emmett-Teller) surface area measurement.

Results: Both metallic nanoparticles were found to inhibit the growth of microbes. However, One-way ANOVA of the IC50 of microbial growth inhibition profile shows significant mean difference between DGL—SNPs and DGL—ZNPs; DGL—SNPs showed improved outcome to the DGL—ZNPs with a P value of at. The surface Plasmon resonance absorption peak of 275 and 261 nm for DGL—SNPs and DGL—ZNPs respectively; FTIR analysis revealed the presence of phytochemicals such as phenol, saponin, and alkaloid that play the major roles in stabilizing the DGL—SNPs and DGL—ZNPs. XRD result shows a crystallite size of 27.9 nm and 22.6 nm from the width of the principal peak reflection of (0 1 3) and (1 2 2) respectively for DGL—SNPs and DGL—ZNPs; EDX shows the formation of Silver atoms and ZnO in the DGL—SNPs and DGL—ZNPs; from the BET, the average particle size 59.76 nm for silver and 70.17 nm for zinc. The SEM showed the irregular structure of DGL—SNPs and DGL—ZNPs.

Conclusion: There is a significant difference in the antimicrobial properties of silver nanoparticles and zinc nanoparticles as a promising agent against human pathogens.