title: Nanotoxicity of graphene oxide: Assessing the influence of oxidation debris in the presence of humic acid.
abstract: This study sought to evaluate the toxicological effects of graphene oxide (GO) through tests with Danio rerio (zebrafish) embryos, considering the influence of the base washing treatment and the interaction with natural organic matter (i.e., humic acid, HA). A commercial sample of GO was refluxed with NaOH to remove oxidation debris (OD) byproducts, which resulted in a base washed GO sample (bw-GO). This process decreased the total oxygenated groups in bw-GO and its stability in water compared to GO. When tested in the presence of HA, both GO and bw-GO stabilities were enhanced in water. Although the embryo exposure showed no acute toxicity or malformation, the larvae exposed to GO showed a reduction in their overall length and acetylcholinesterase activity. In the presence of HA, GO also inhibited acid phosphatase activity. Our findings indicate a mitigation of material toxicity after OD removal. The difference in the biological effects may be related to the materials' bioavailability and biophysicochemical interactions. This study reports for the first time the critical influence of OD on the GO material biological reactivity and HA interaction, providing new data for nanomaterial environmental risk assessment and sustainable nanotechnology.
authors.affiliation: Laboratory of Ecotoxicology and Biosafety, Brazilian Agricultural Research Corporation (Embrapa Environment), Jaguariúna, SP, Brazil; Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil. Electronic address: zairaclemente@hotmail.com.
authors.forename: Zaira
authors.initials: Z
authors.lastname: Clemente
authors.affiliation: Laboratory of Ecotoxicology and Biosafety, Brazilian Agricultural Research Corporation (Embrapa Environment), Jaguariúna, SP, Brazil.
authors.forename: Vera Lúcia S S
authors.initials: VLSS
authors.lastname: Castro
authors.affiliation: Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil.
authors.forename: Lidiane S
authors.initials: LS
authors.lastname: Franqui
authors.affiliation: Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil.
authors.forename: Cristiane A
authors.initials: CA
authors.lastname: Silva
authors.affiliation: Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil.
authors.forename: Diego Stéfani T
authors.initials: DST
authors.lastname: Martinez
mesh_terms: D000818:Animals; D006108:Graphite / Q000633:toxicity*; D006812:Humic Substances; D049329:Nanostructures / Q000633:toxicity*; D010084:Oxidation-Reduction; D010087:Oxides; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish
chemical_list: D006812:Humic Substances; D010087:Oxides; D014874:Water Pollutants, Chemical; D006108:Graphite
keywords: Biomarker; Embryotoxicity; Nanoecotoxicology; Nanotechnology; Zebrafish