Enhanced Antimicrobial and Anticancer Activity of Silver and Gold Nanoparticles Synthesised Using Sargassum incisifolium Aqueous Extracts

Molecules. 2016 Dec 2;21(12):1633. doi: 10.3390/molecules21121633.

Abstract

A detailed, methodical approach was used to synthesise silver and gold nanoparticles using two differently prepared aqueous extracts of the brown algae Sargassum incisifolium. The efficiency of the extracts in producing nanoparticles were compared to commercially available brown algal fucoidans, a major constituent of brown algal aqueous extracts. The nanoparticles were characterised using TEM, XRD and UV/Vis spectroscopy and zeta potential measurements. The rate of nanoparticle formation was assessed using UV/Vis spectroscopy and related to the size, shape and morphology of the nanoparticles as revealed by TEM. The antioxidant, reducing power and total polyphenolic contents of the aqueous extracts and fucoidans were determined, revealing that the aqueous extracts with the highest contents produced smaller, spherical, more monodisperse nanoparticles at a faster rate. The nanoparticles were assessed against two gram-negative bacteria, two gram-positive bacteria and one yeast strain. In contrast to the literature, the silver nanoparticles produced using the aqueous extracts were particularly toxic to Gram-negative bacteria, while the gold nanoparticles lacked activity. The cytotoxic activity of the nanoparticles was also evaluated against cancerous (HT-29, MCF-7) and non-cancerous (MCF-12a) cell lines. The silver nanoparticles displayed selectivity, since the MCF-12a cell line was found to be resistant to the nanoparticles, while the cancerous HT-29 cell line was found to be sensitive (10% viability). The gold nanoparticles displayed negligible toxicity.

Keywords: Sargassum incisifolium; antibacterial activity; cytotoxicity; fucoidans; gold nanoparticles; green synthesis; silver nanoparticles; total phenolic content.

MeSH terms

  • Acinetobacter baumannii / drug effects
  • Anti-Bacterial Agents / chemical synthesis
  • Anti-Bacterial Agents / pharmacology*
  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / pharmacology*
  • Candida albicans / drug effects
  • Cell Line, Tumor
  • Drug Resistance, Multiple, Bacterial / drug effects
  • Enterococcus faecalis / drug effects
  • Gold / pharmacology*
  • Green Chemistry Technology
  • HT29 Cells
  • Humans
  • Klebsiella pneumoniae / drug effects
  • MCF-7 Cells
  • Metal Nanoparticles / therapeutic use*
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Microbial Sensitivity Tests
  • Microscopy, Electron, Transmission
  • Particle Size
  • Plant Extracts / pharmacology*
  • Sargassum / chemistry*
  • Silver / pharmacology*
  • Spectrometry, X-Ray Emission

Substances

  • Anti-Bacterial Agents
  • Antineoplastic Agents
  • Plant Extracts
  • Silver
  • Gold