Background

Bivalves can accumulate and concentrate most pollutants, even if they are present in somewhat low concentrations. The present study aimed to use freshwater bivalveas for the first time as vital indicator for silver/chitosan nanocomposites (Ag-CS NCs) in the freshwater environment.

Methods

Following the preparation and characterization of Ag-CS NCs by using UV–vis spectrophotometer, X-ray diffraction, transmission electron microscopy, and acute toxicity study, the animals exposed to three different dose of nano chitosan (CS), AgNPs, and Ag-CS NCs (12.5, 25 and 50 mg/L) for consecutive 6 days.

Results

Ag-CS particles were in size range of 8–19 nm. The nominal concentrations for Ag-CS NCs were 12.5, 25 and 50 mg Ag L⁻¹ were corresponding to measured concentration of AgNPs 0.37, 0.81, and 1.65 mg Ag L⁻¹, respectively. All concentrations of Ag-CS NCs caused a significant increase in MDA and NO, while GSH and CAT levels decreased significantly in all organs. Histological investigation of the gills, labial palp and foot tissues showed alternation after exposure to Ag-CS NCs, especially at dose 50 mg/L.

Conclusion

The present study showed that exposure to Ag-CS NCs caused oxidative stress responses in Coelatura aegyptiaca and histological changes in the organs. These physiological and histological changes observed after exposure to Ag-CS NCs were most likely the result of the action of AgNPs themselves while the effect of chitosan on these changes was negligible. We concluded that Coelatura aegyptiaca was a sensitive bio-indicator for monitoring of the past and the present water pollution by nanoparticles.

中文翻译：

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银/壳聚糖纳米复合材料诱导淡水双壳类动物的生理和组织学变化

背景

双壳类动物可以积累和浓缩大多数污染物，即使它们的浓度有点低。本研究旨在首次使用淡水双壳类动物作为淡水环境中银/壳聚糖纳米复合材料 (Ag-CS NCs) 的重要指标。

方法

在使用紫外-可见分光光度计、X 射线衍射、透射电子显微镜和急性毒性研究制备和表征 Ag-CS NCs 之后，动物暴露于三种不同剂量的纳米壳聚糖 (CS)、AgNPs 和 Ag- CS NCs（12.5、25 和 50 mg/L）连续 6 天。

结果

Ag-CS 颗粒的尺寸范围为 8-19 nm。Ag-CS NC 的标称浓度为12.5、25和 50 mg Ag L ^{-1 ，}分别对应于测量的 AgNP 浓度 0.37、0.81 和 1.65 mg Ag L ^-1。所有浓度的 Ag-CS NCs 均导致 MDA 和 NO 显着增加，而所有器官中的 GSH 和 CAT 水平显着降低。鳃、唇缘和足部组织的组织学研究表明，在暴露于 Ag-CS NCs 后，尤其是在剂量为 50 mg/L 时发生了交替。

结论

本研究表明，暴露于 Ag-CS NCs 会导致Coelatura aegyptiaca 的氧化应激反应和器官的组织学变化。暴露于 Ag-CS NCs 后观察到的这些生理和组织学变化很可能是 AgNPs 本身作用的结果，而壳聚糖对这些变化的影响可以忽略不计。我们的结论是Coelatura aegyptiaca是一种敏感的生物指标，用于监测纳米粒子的过去和现在的水污染。