hrvatski

Evaluation of the Embryotoxicity of Nanosized Zeolite Beta

Zeolites are widely used in various fields of human activities [1] and as such there are many particular cases when large amounts of zeolite powder can be released to certain area and have a potentially harmful effect on specific ecosystem. Therefore, the goal of this research is to prepare nanosized zeolite beta particles and evaluate their toxicity towards chosen representatives of vertebrates. For this reason zebrafish embryotoxicity test was performed [2] on two zeolite beta samples having different size. Zeolite beta samples have been prepared by hydrothermal treatment of alumosilicate precursors of molar oxide composition 0.35Na2O : 0.5Al2O3 : 25SiO2 : 9TEAOH : 295H2O at 100 °C 7 days and 1.23K2O : 1.23Na2O : 1Al2O3 : 50SiO2 : 25TEAOH : 745H2O at 140 °C for 30 h. The average size of synthesized zeolite Beta crystals was 140 nm and 640 nm, respectively. The washed samples have been freeze- dried and calcined at 550 °C. The solid product was characterized by XRD, DLS, TEM and TG. Prior testing, both merely dried and calcined powder have been dispersed in artificial water in three different concentrations. In addition, tetraethylammonium hydroxide solutions of corresponding concentrations have been prepared for the test. Standardized zebrafish Danio rerio embryotoxicity test has been conducted as follows: embryos have been exposed to zeolite beta suspensions up to 72 hours post fertilization (hpf), followed by determination of lethal (coagulation of the embryo, non- detachment of the tail, lack of heart beat and no somite formation) and sublethal effects (developmental retardation, deformations, formation of edems, blood accumulation, etc) of tested nanosized zeolites. In addition, at 48 and 72 hpf heart beat and hatching rate were evaluated, as well as pigmentation formation. All experiments have been performed on the non- protected embryonal stages, which do not require permission by animal welfare commissions. The collected data have been statistically analyzed. Results indicate the zeolites do exhibit a certain effect on the development of the Danio rerio embryos, but they are not lethal. The obtained results have showed that selected model organisms could improve our ability to understand the mechanism of the toxicity of alumosilicates, and should be incorporated in nanoparticles toxicity monitoring and risk assessment studies. Additionally, this research focuses on the importance of an early and accurate determination of the toxic potential of the nanoparticles to assess its further use.

nanosize ; zeolite ; embryotoxicity

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