title: Comparative in vitro toxicity of a graphene oxide-silver nanocomposite and the pristine counterparts toward macrophages.
abstract: BACKGROUND
  Graphene oxide (GO) is a highly oxidized graphene form with oxygen functional groups on its surface. GO is an excellent platform to support and stabilize silver nanoparticles (AgNP), which gives rise to the graphene oxide-silver nanoparticle (GOAg) nanocomposite. Understanding how this nanocomposite interacts with cells is a toxicological challenge of great importance for future biomedical applications, and macrophage cells can provide information concerning the biocompatibility of these nanomaterials. The cytotoxicity of the GOAg nanocomposite, pristine GO, and pristine AgNP was compared toward two representative murine macrophages: a tumoral lineage (J774) and peritoneal macrophages collected from Balb/c mouse. The production of reactive oxygen species (ROS) by J774 macrophages was also monitored. We investigated the internalization of nanomaterials by transmission electron microscopy (TEM). The quantification of internalized silver was carried out by inductively coupled plasma mass spectrometry (ICP-MS). Nanomaterial stability in the cell media was investigated overtime by visual observation, inductively coupled plasma optical emission spectrometry (ICP OES), and dynamic light scattering (DLS).
  
  
  RESULTS
  The GOAg nanocomposite was more toxic than pristine GO and pristine AgNP for both macrophages, and it significantly induced more ROS production compared to pristine AgNP. TEM analysis showed that GOAg was internalized by tumoral J774 macrophages. However, macrophages internalized approximately 60 % less GOAg than did pristine AgNP. The images also showed the degradation of nanocomposite inside cells.
  
  
  CONCLUSIONS
  Although the GOAg nanocomposite was less internalized by the macrophage cells, it was more toxic than the pristine counterparts and induced remarkable oxidative stress. Our findings strongly reveal a synergistic toxicity effect of the GOAg nanocomposite. The toxicity and fate of nanocomposites in cells are some of the major concerns in the development of novel biocompatible materials and must be carefully evaluated.
authors.affiliation: Laboratory of Solid State Chemistry (LQES), Institute of Chemistry, University of Campinas, Campinas, Brazil. luisvisani@gmail.com.|Laboratory of Leishmaniasis (Lableish), Institute of Biology, University of Campinas, Campinas, Brazil. luisvisani@gmail.com.
authors.forename: Luis Augusto Visani
authors.initials: LA
authors.lastname: de Luna
authors.affiliation: Laboratory of Solid State Chemistry (LQES), Institute of Chemistry, University of Campinas, Campinas, Brazil. anacmmo@gmail.com.
authors.forename: Ana Carolina Mazarin
authors.initials: AC
authors.lastname: de Moraes
authors.affiliation: Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil. silviorconsonni@yahoo.com.br.|Laboratory of Cytochemistry and Immunocytochemistry (LCI), Institute of Biology, University of Campinas, Campinas, Brazil. silviorconsonni@yahoo.com.br.
authors.forename: Sílvio Roberto
authors.initials: SR
authors.lastname: Consonni
authors.affiliation: Atomic Spectrometry Group (GEAtom), Institute of Chemistry, University of Campinas, Campinas, Brazil. catarinie.dp@gmail.com.
authors.forename: Catarinie Diniz
authors.initials: CD
authors.lastname: Pereira
authors.affiliation: Atomic Spectrometry Group (GEAtom), Institute of Chemistry, University of Campinas, Campinas, Brazil. cadore@iqm.unicamp.br.
authors.forename: Solange
authors.initials: S
authors.lastname: Cadore
authors.affiliation: Laboratory of Leishmaniasis (Lableish), Institute of Biology, University of Campinas, Campinas, Brazil. selmagiorgio@gmail.com.
authors.forename: Selma
authors.initials: S
authors.lastname: Giorgio
authors.affiliation: Laboratory of Solid State Chemistry (LQES), Institute of Chemistry, University of Campinas, Campinas, Brazil. oalves@iqm.unicamp.br.
authors.forename: Oswaldo Luiz
authors.initials: OL
authors.lastname: Alves
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects; D045744:Cell Line, Tumor; D037741:Fullerenes / Q000009:adverse effects*; D006108:Graphite / Q000009:adverse effects*; D008264:Macrophages / Q000187:drug effects*; D053768:Metal Nanoparticles / Q000009:adverse effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D053761:Nanocomposites / Q000009:adverse effects*; D010087:Oxides / Q000009:adverse effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012834:Silver / Q000009:adverse effects*
chemical_list: D001672:Biocompatible Materials; D037741:Fullerenes; D010087:Oxides; D017382:Reactive Oxygen Species; C530172:pristine (C60); D012834:Silver; D006108:Graphite