title: Adsorption characteristics of nano-TiO2 onto zebrafish embryos and its impacts on egg hatching.
abstract: The characteristics of nanoparticles (NPs) uptake may fundamentally alter physicochemical effects of engineered NPs on aquatic organisms, thereby yielding different ecotoxicology assessment results. The adsorption behavior of nano-TiO2 (P-25) on zebrafish embryos in Holtfreter's medium (pH 7.2, I ∼ 7.2 × 10(-2) M) and the presence of sodium alginate (100 mg/L) as dispersant was investigated. Zebrafish embryos (total 100) were exposed to nano-TiO2 at different concentrations (e.g., 0, 10, 20, 60, 120 mg/L) in batch-mode assay. The adsorption capacity of nano-TiO2 on fish eggs was determined by measuring the Ti concentration on the egg surface using ICP-OES analysis. Results showed that the adsorption capacity increased rapidly in the first hour, and then declined to reach equilibrium in 8 h. The adsorption characteristics was visualized as a three-step process of rapid initial layer formation, followed by break-up of aggregates and finally rearrangement of floc structures; the maximum adsorption capacity was the sum of an inner rigid layers of aggregates of 0.81-0.84 μg-TiO2/#-egg and an outer softly flocculated layers of 1.01 μg-TiO2/#-egg. The Gibbs free energy was 543.29-551.26 and 100.75 kJ/mol, respectively, for the inner-layer and the outer-layer aggregates. Adsorption capacity at 0.5-1.0 μg-TiO2/#-egg promoted egg hatching; but hatching was inhibited at higher adsorption capacity. Results clearly showed that the configuration of TiO2 aggregates could impact the hatching efficiency of zebrafish embryos.
authors.affiliation: Department of Marine Environmental Engineering, National Kaohsiung Marine University, Kaohsiung 81157, Taiwan, ROC.
authors.forename: Yu-Jen
authors.initials: YJ
authors.lastname: Shih
authors.affiliation: Department of Marine Environmental Engineering, National Kaohsiung Marine University, Kaohsiung 81157, Taiwan, ROC.
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Su
authors.affiliation: Department of Marine Environmental Engineering, National Kaohsiung Marine University, Kaohsiung 81157, Taiwan, ROC.
authors.forename: Chiu-Wen
authors.initials: CW
authors.lastname: Chen
authors.affiliation: Department of Marine Environmental Engineering, National Kaohsiung Marine University, Kaohsiung 81157, Taiwan, ROC.
authors.forename: Cheng-Di
authors.initials: CD
authors.lastname: Dong
authors.affiliation: Asia-Pacific Biotech Developing Inc., Kaohsiung, Taiwan, ROC.
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: Liu
authors.affiliation: Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716, USA. Electronic address: huang@udel.edu.
authors.forename: C P
authors.initials: CP
authors.lastname: Huang
mesh_terms: D000327:Adsorption; D000818:Animals; D001692:Biological Transport; D054750:Ecotoxicology; D053758:Nanoparticles / Q000737:chemistry*; D010058:Oviposition / Q000187:drug effects*; D014025:Titanium / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity*; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism / Q000502:physiology
chemical_list: C009495:titanium dioxide; D014025:Titanium
keywords: Adsorption; Embryos; Flocculation; Hatching; TiO(2); Zebrafish