Preparation, characterization, and antibacterial activity of Moringa oleifera‑silver nanoparticles-kaolinite nanocomposite

Abstract

Although extensive research has been conducted on the synthesis of silver nanoparticles (AgNPs) using Moringa oleifera leaf extract for various applications, the synthesis and antibacterial efficacy of M. oleifera-synthesized AgNPs immobilized onto a kaolinite carrier remains unexplored. This study introduces the formulation of a novel Moringa oleifera (Mo)-Silver Nanoparticle (AgNP)-Kaolinite nanocomposite (Mo-Ag-Kao) synthesized through the green method. The nanocomposite was developed by incorporating biosynthesized AgNPs into kaolinite to enhance its stability and antimicrobial efficacy. The nanocomposite was characterized using various analytical techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), thermogravimetric-differential thermal analysis (TGA-DTA), and zeta potential analysis. The characterization results revealed the successful incorporation of spherical AgNPs that were synthesized using M. oleifera extract onto kaolinite, with an average particle size of 20 nm. Additionally, the kaolinite structure still remained in the Mo-Ag-Kao nanocomposite, and it demonstrated high thermal stability (up to 700 °C). The nanocomposite showed strong antibacterial properties against a broad spectrum of bacterial strains, including Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. In conclusion, the use of kaolinite as a carrier for AgNPs not only prevents nanoparticle aggregation but also enhances its antibacterial efficacy.