Green Synthesis of Silver Nanoparticles Using Cola nitida Nut Extract (Vent.) Schott & Endl. (Malvaceae), Characterization and the Determination of their Antimicrobial Activity

Abstract

Pathogenic microorganisms have developed resistance to existing antibiotics at an alarming rate; this has encouraged researchers to make a shift to the development of new drugs. One of the new developments used is the synthesis of silver nanoparticles (AgNPs). The aim of this study was to characterize and evaluate the antimicrobial activity of silver nanoparticle synthesized using Cola nitida nut extract. The AgNPs were synthesized by mixing 150 mL of silver nitrate solution (1 mM) with 750 mL of aqueous extract of Cola nitida nut at room temperature. Characterization of the synthesized AgNPs was done by UV-VIS, FTIR and particle size analysis. AgNPs were screened against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Candida albicans and Aspergillus niger. The result of the UV-VIS analysis showed the maximum absorbance wavelength of 439 nm at 4.5 h while FTIR showed the presence of functional groups such as alcohols and amides in the AgNPs. The particle size analysis showed that the average particle size was 227.2 nm. The antimicrobial screening showed that the AgNPs have activity against P. aeruginosa and B. subtilis with inhibition zone diameter of 8 mm and 6 mm respectively. The minimum inhibitory concentration (MIC) against S. typhi, S. aureus and C. albicans was 9 µg/mL for each of the organisms. The MIC for each of E. coli and A. niger was 10 µg/mL while that of B. subtilis was 7 µg/mL. The synthesized silver nanoparticles were found to be stable and effective against the microorganisms.