Optimization of Commercial Antibiotic Agents Using Gold Nanoparticles Against Toxigenic Aspergillus spp

Velaphi C. Thipe, Patrick B. Njobeh, Sabelo D. Mhlanga

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The synthesis and application of gold nanoparticles (AuNPs) has been intensively studied by researchers all over the world. However, their application on enhancing the antifungal activity of antibiotics has not been fully explored. We have considered that various physiochemical methods used to synthesize AuNPs that are reported in the literature are energy driven, costly and require the use of harmful chemicals in the process, making them not environmentally-friendly. This paper reports the synthesis of AuNPs via a greener route using Aspalathus linearis tea leaves, which were subsequently used to optimize the antifungal activity of some commercial antifungal discs, i.e., amphotericin B, fluconazole, clotrimazole, econazole, flucytosine, ketoconazole, miconazole and nystatin using AuNPs against four Aspergillus spp. The AuNPs were characterized using ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The toxicity of the synthesized AuNPs was studied by 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxypheny l)-2-(4-sulfophenyl)-2H-tetrazolium) assay and xCELLigence test on HepG-2 cell lines and the results revealed very little to no toxicity of the AuNPs. The AuNP coated antibiotic discs were characterized by FTIR, scanning electron microscopy (SEM) and antifungal activity was performed using the disc diffusion method. A strong resonance peak was observed at 528. nm of the AuNPs measured using UV-vis spectroscopy. The average size of AuNPs was ~41±1. nm and they demonstrated moderate in-vitro stability under various solutions (5% NaCl, phosphate buffered saline) at varying pH levels. SEM images revealed that the AuNPs were attached onto the discs. Antifungal results indicated that AuNPs significantly (p<0.001) enhanced the antifungal activity of antibiotic discs against the tested fungi with AuNP coated econazole disc exhibiting the greatest activity than for other agents tested. In conclusion, an aqueous extract of A. linearis tea leaves could be used as a reducing agent in the synthesis of stable AuNPs, some of which demonstrated considerable activity in enhancing the antifungal activity of pristine antibiotic agents. These AuNPs can therefore be of great significance towards the development of fungicidal agents for medical and veterinary applications.

Original languageEnglish
Pages (from-to)4136-4148
Number of pages13
JournalMaterials Today: Proceedings
Issue number7
Publication statusPublished - 2015


  • Antifungal activity
  • Antifungal agents
  • Aspalathus linearis
  • Gold nanoparticles
  • Green synthesis

ASJC Scopus subject areas

  • General Materials Science


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