Sandra Vranic: Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan. sandra.vranic@manchester.ac.uk.
Yasuhito Shimada: Department of Integrative Pharmacology, Mie University Graduate School of Medicine, Tsu 514-8572, Japan. shimada.yasuhito@mie-u.ac.jp. ORCID
Sahoko Ichihara: Department of Environmental and Preventive Medicine, Jichi Medical University School of Medicine, Shimotsuke 329-0498, Japan. saho@jichi.ac.jp. ORCID
Masayuki Kimata: Department of Human Functional Genomics, Life Science Research Center, Mie University, Tsu 514-8572, Japan. mk.lucky-seven@ezweb.ne.jp.
Wenting Wu: Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan. wendywu1206@163.com.
Toshio Tanaka: Department of Systems Pharmacology, Mie University Graduate School of Medicine, Tsu 514-8572, Japan. tanaka@doc.medic.mie-u.ac.jp.
Sonja Boland: Unit of Functional and Adaptive Biology (BFA), Laboratory of Molecular and Cellular Responses to Xenobiotics, CNRS UMR 8251, Universite Paris Diderot, Sorbonne Paris Cite, 75013 Paris, France. boland@univ-paris-diderot.fr. ORCID
Lang Tran: Institute of Occupational Medicine, Research Avenue North, Riccarton, Edinburgh EH14 4AP, UK. lang.tran@iom-world.org.
Gaku Ichihara: Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan. gak@rs.tus.ac.jp.
As the use of nanoparticles (NPs) is increasing, the potential toxicity and behavior of NPs in living systems need to be better understood. Our goal was to evaluate the developmental toxicity and bio-distribution of two different sizes of fluorescently-labeled SiO₂ NPs, 25 and 115 nm, with neutral surface charge or with different surface functionalization, rendering them positively or negatively charged, in order to predict the effect of NPs in humans. We performed a zebrafish embryo toxicity test (ZFET) by exposing the embryos to SiO₂ NPs starting from six hours post fertilization (hpf). Survival rate, hatching time, and gross morphological changes were assessed at 12, 24, 36, 48, 60, and 72 hpf. We evaluated the effect of NPs on angiogenesis by counting the number of sub-intestinal vessels between the second and seventh intersegmental vessels and gene expression analysis of vascular endothelial growth factor (VEGF) and VEGF receptors at 72 hpf. SiO₂ NPs did not show any adverse effects on survival rate, hatching time, gross morphology, or physiological angiogenesis. We found that SiO₂ NPs were trapped by the chorion up until to the hatching stage. After chemical removal of the chorion (dechorionation), positively surface-charged SiO₂ NPs (25 nm) significantly reduced the survival rate of the fish compared to the control group. These results indicate that zebrafish chorion acts as a physical barrier against SiO₂ NPs, and removing the chorions in ZFET might be necessary for evaluation of toxicity of NPs.
