Green Synthesis, Characterization, and Antibacterial Investigation of Synthesized Gold Nanoparticles (AuNPs) from Garcinia kola Pulp Extract

The properties of gold nanoparticles, such as conductivity, half-life, catalytic nature, improved solubility efficiency, chemical stability, and its mechanism in binding with bacterial cell wall to induce cell death, have increased its medicinal applications. This study investigated the antibacterial property of gold nanoparticles (AuNPs) synthesized from Garcinia kola pulp extract. The ripe fruits of Garcinia kola were obtained, and the pulps were removed, air dried, pulverized, extracted, and mixed with gold chloride solution following standard procedure. The synthesized AuNPs were characterized using ultraviolet visible spectrophotometer (UV-visible), Fourier transform infrared (FTIR) spectrophotometer, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX). The antibacterial examination was carried out on four clinical isolate bacteria using agar diffusion technique. The UV-visible analysis confirmed the formation of stable AuNPs at pH 7 in the wavelength region of 564 nm. The FTIR analysis confirmed that the secondary metabolites with –OH functional groups serve as the reducing agent for the synthesis of AuNPs. The morphological assessment of the synthesized AuNPs revealed spherical-shaped particles. The zones of inhibition of the synthesized AuNPs against test bacteria ranges from 3 to 13 mm while that of the control was in the range of 14 to 22 mm. This study provided an environmentally friendly approach in the synthesis of AuNPs from Garcinia kola pulps and also ascertained the medicinal application of the synthesized AuNPs as an antibacterial agent.