title: Effect of graphene oxide on bacteria and peripheral blood mononuclear cells.
abstract: BACKGROUND
  Driven by the potential biological applications of graphene, many groups have studied the response of cells exposed to graphene oxide (GO). In particular, investigations of bacteria indicate that there are 2 crucial parameters, which so far have only been investigated separately: GO size and exposure methodology. Our study took into account both parameters. We carefully characterized the samples to catalog sizes and structural properties, and tested different exposure methodologies: exposure in saline solution and in the presence of growth media. Furthermore, we performed experiments with peripheral blood mononuclear cells exposed to our GO materials.
  
  
  METHODS
  Atomic force microscopy, scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy were used to characterize the morphology and composition of different samples of GO: GO-H2O, GO-PBS and GO-MG. Our samples had 2D sizes of ~100 nm (GO-H2O and GO-PBS) and &gt;2 µm (GO-MG). We tested antibacterial activity and cytotoxicity toward peripheral blood mononuclear cells of 3 different GO samples.
  
  
  RESULTS
  A size-dependent growth inhibition of Escherichia coli (DH5 α) in suspension was found, which proved that this effect depends strongly on the protocol followed for exposure. Hemocompatibility was confirmed by exposing peripheral blood mononuclear cells to materials for 24 hours; viability and apoptosis tests were also carried out.
  
  
  CONCLUSIONS
  Our experiments provide vital information for future applications of GO in suspension. If its antibacterial properties are to be potentiated, care should be taken to select 2D sizes in the micrometer range, and exposure should not be carried out in the presence of grow media.
authors.affiliation: CIACYT, Universidad Autónoma de San Luis Potosí, San Luis Potosí - México.
authors.forename: Jessica
authors.initials: J
authors.lastname: Campos-Delgado
authors.affiliation: DIMAT, INMETRO, Xerem, Rio de Janeiro - Brazil.
authors.forename: Kelly L S
authors.initials: KL
authors.lastname: Castro
authors.affiliation: Department of Molecular Biology, IPICYT, San Luis Potosí - México.
authors.forename: Jose G
authors.initials: JG
authors.lastname: Munguia-Lopez
authors.affiliation: CIACYT, Universidad Autónoma de San Luis Potosí, San Luis Potosí - México.
authors.forename: Ana K
authors.initials: AK
authors.lastname: González
authors.affiliation: DIMAT, INMETRO, Xerem, Rio de Janeiro - Brazil.
authors.forename: Martin E
authors.initials: ME
authors.lastname: Mendoza
authors.affiliation: Departamento de Física, UFJF, Juiz de Fora - Brazil.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Fragneaud
authors.affiliation: DIMAT, INMETRO, Xerem, Rio de Janeiro - Brazil.
authors.forename: Raphael
authors.initials: R
authors.lastname: Verdan
authors.affiliation: DIMAT, INMETRO, Xerem, Rio de Janeiro - Brazil.
authors.forename: Joyce R
authors.initials: JR
authors.lastname: Araujo
authors.affiliation: CIACYT, Universidad Autónoma de San Luis Potosí, San Luis Potosí - México.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: González
authors.affiliation: CIACYT, Universidad Autónoma de San Luis Potosí, San Luis Potosí - México.
authors.forename: Hugo
authors.initials: H
authors.lastname: Navarro-Contreras
authors.affiliation: CIACYT, Universidad Autónoma de San Luis Potosí, San Luis Potosí - México.
authors.forename: Ivan N
authors.initials: IN
authors.lastname: Pérez-Maldonado
authors.affiliation: Department of Molecular Biology, IPICYT, San Luis Potosí - México.
authors.forename: Antonio de
authors.initials: A
authors.lastname: León-Rodríguez
authors.affiliation: DIMAT, INMETRO, Xerem, Rio de Janeiro - Brazil.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Achete
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004926:Escherichia coli / Q000254:growth & development* / Q000648:ultrastructure*; D006108:Graphite / Q000494:pharmacology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism* / Q000648:ultrastructure*; D050296:Microbial Viability / Q000187:drug effects
chemical_list: D006108:Graphite