Antimicrobial and cytotoxic activity of biosynthesized gold nanoparticles

Abstract

We present a simple and eco-friendly biosynthesis of gold nanoparticles (AuNPs) using naturally available Malus domestica fruit extract as a reducing, capping and stabilizing agent. The reaction process was simple and safe for the formation of highly stable AuNPs at room temperature by using the fruit extract. The surface plasmon resonance (SPR) band in UV-vis spectrum showed the reduction of auric acid to gold nanoparticles at 533 nm. The morphology of the nanoparticles was determined from high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD). The HRTEM images showed the mixture of spherical and triangular shapes of biosynthesized AuNPs having size ranging between 5 and 20 nm. Thermogravimetric analysis (TGA) was employed to determine the thermal stability of the AuNPs. They were also characterized by Fluorescence, Raman and Infrared (IR) spectroscopy. The biosynthesized AuNPs showed excellent antibacterial and anticancer activity. The gold nanoparticle synthesized using apple extract showed higher activity against Aspergillus flavus (MIC: 0.31 mg/mL) followed by, Staphylococcus aureus (MIC: 0.34 mg/mL), Salmonella typhi (MIC: 0. 63 mg/mL) and Candida albicans. Very low activity was found against Vibreo cholerae (MIC: 2.50 mg/mL). MTT assay was used to determine the cytotoxicity of biosynthesized gold nanoparticles on HeLa cancer cells.