Background As an emerging nanomaterial, nano-alumina is widely used in chemical, biological, and electronic industries and composite materials due to its special physical and chemical properties, attracting increasing attention to its potential health hazards.
Objective The purpose of this study is to investigate the damage to the learning and memory levels of adult zebrafish by nano-alumina particles, and the roles of particle size and dissolved aluminum ions.
Methods To evaluate the effects of particle size, zebrafishes at 3 months old were divided into three groups:control group, 13 nm nano-alumina group, and 50 nm nano-alumina group. To investigate the individual role of particle size or dissolved aluminum ion of nano-alumina, zebrafishes at 3 months old were divided into four groups:control group, 50 nm nano-alumina group, 50 nm nano-carbon group, and AlCl3 group. The concentrations of nano-alumina and nano-carbon group were both set at 100mg/L, and the concentration of AlCl3 was 100μg/L. After 30 days of exposure, T-maze test was performed and a video tracking system were used to record the trajectory and analyze the behavioral indicators of zebrafish, including the first latencythe time from the start of the experiment to the first entry into the enriched chamber (EC) and cumulative duration (total time spent in the EC).
Results Compared with the control group, the exposure groups showed different degrees of chaotic trajectories and reduced duration in the EC. In the study of particle size, the first latency was not different between the 13 nm nano-alumina group and the 50 nm nanoalumina group; the cumulative duration in the 13 nm nano-alumina group was significantly lower than that in the 50 nm nano-alumina group on the first and second days of the experiment (P < 0.05). In the study of particle size and ion, the first latency in the 50 nm nanoalumina group was prolonged compared with the 50 nm nano-carbon group on the third and fourth days of the experiment (P < 0.05), but no statistical difference was found between the 50 nm nano-alumina group and the AlCl3 group (P > 0.05); the cumulative duration in the 50 nm nano-alumina group in the EC on the first day was reduced compared with the 50 nm nano-carbon group (P < 0.05), but no statistical difference was found between the 50 nm nano-alumina group and the AlCl3 group (P > 0.05). According to the zebrafish trajectory map, the control group showed a more orderly trajectory, longer cumulative duration in the EC, and less duration in the opposite area than the other groups, indicating a good learning and memory level.
Conclusion Nano-alumina can cause learning and memory disorders in adult zebrafish. A smaller particle size of nano-alumina is linked to a greater toxicity to learning and memory of zebrafish. Aluminum ions play an important role in the effect of 50 nm nano-alumina on the learning and memory levels of zebrafish.
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