title: Green synthesis of silver nanoparticles using Ganoderma neo-japonicum Imazeki: a potential cytotoxic agent against breast cancer cells.
abstract: BACKGROUND
  Silver nanoparticles (AgNPs) are an important class of nanomaterial for a wide range of industrial and biomedical applications. AgNPs have been used as antimicrobial and disinfectant agents due their detrimental effect on target cells. The aim of our study was to determine the cytotoxic effects of biologically synthesized AgNPs using hot aqueous extracts of the mycelia of Ganoderma neo-japonicum Imazeki on MDA-MB-231 human breast cancer cells.
  
  
  METHODS
  We developed a green method for the synthesis of water-soluble AgNPs by treating silver ions with hot aqueous extract of the mycelia of G. neo-japonicum. The formation of AgNPs was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. Furthermore, the toxicity of synthesized AgNPs was evaluated using a series of assays: such as cell viability, lactate dehydrogenase leakage, reactive oxygen species generation, caspase 3, DNA laddering, and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling in human breast cancer cells (MDA-MB-231).
  
  
  RESULTS
  The ultraviolet-visible absorption spectroscopy results showed a strong resonance centered on the surface of AgNPs at 420 nm. The X-ray diffraction analysis confirmed that the synthesized AgNPs were single-crystalline, corresponding with the result of transmission electron microscopy. Treatment of MDA-MB-231 breast cancer cells with various concentrations of AgNPs (1-10 μg/mL) for 24 hours revealed that AgNPs could inhibit cell viability and induce membrane leakage in a dose-dependent manner. Cells exposed to AgNPs showed increased reactive oxygen species and hydroxyl radical production. Furthermore, the apoptotic effects of AgNPs were confirmed by activation of caspase 3 and DNA nuclear fragmentation.
  
  
  CONCLUSIONS
  The results indicate that AgNPs possess cytotoxic effects with apoptotic features and suggest that the reactive oxygen species generated by AgNPs have a significant role in apoptosis. The present findings suggest that AgNPs could contribute to the development of a suitable anticancer drug, which may lead to the development of a novel nanomedicine for the treatment of cancers.
authors.affiliation: Department of Animal Biotechnology, Konkuk University, Seoul, South Korea.
authors.forename: Sangiliyandi
authors.initials: S
authors.lastname: Gurunathan
authors.forename: Jegadeesh
authors.initials: J
authors.lastname: Raman
authors.forename: Sri Nurestri
authors.initials: SN
authors.lastname: Abd Malek
authors.forename: Priscilla A
authors.initials: PA
authors.lastname: John
authors.forename: Sabaratnam
authors.initials: S
authors.lastname: Vikineswary
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001943:Breast Neoplasms; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D053938:DNA Fragmentation / Q000187:drug effects; D005260:Female; D032902:Ganoderma / Q000378:metabolism*; D055772:Green Chemistry Technology / Q000379:methods*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D018384:Oxidative Stress / Q000187:drug effects; D010316:Particle Size; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D012834:Silver; D053148:Caspase 3
keywords: AgNPs; DNA fragmentation; Ganoderma neo-japonicum; caspase-3 activity; cytotoxicity; human breast cancer cells