# Influence of Silver Fiber Morphology on the Dose–Response Relationship and Enrichment in Daphnia magna Studied by Elemental Imaging with LA-ICP-TOF-MS

## TL;DR

This study investigates how the shape and size of silver nanofibers affect their toxicity and accumulation in water fleas (Daphnia magna).

## Contribution

A novel sample preparation method enabled whole-organism elemental imaging to study nanofiber distribution in Daphnia magna.

## Key findings

- Silver nanofibers showed similar ecotoxicity despite varying dimensions.
- The amount of silver associated with Daphnia neonates differed by a factor of 2–3 between fiber types.
- Both nanofiber types were primarily found in the gut of Daphnia magna.

## Abstract

This study aims to
enhance the understanding of the environmental
risks associated with nanomaterials, particularly nanofibers. Previous
research suggested that silver fibers exhibit higher toxicity (EC50/48h 1.6–8.5 μg/L) compared to spherical silver
particles (EC50/48h 43 μg/L). To investigate the
hypothesis that toxicity is influenced by the morphology and size
of nanomaterials, various silver nanofibers with different dimensions
(length and diameter) were selected. The study assessed their toxicity
toward Daphnia magna using the 48 h
immobilization assay. The EC50 values for the different
fibers ranged from 122 to 614 μg/L. Subsequently, the study
quantified the uptake and distribution of two representative nanofibers
in D. magna neonates by employing digestion
and imaging mass spectrometry in the form of laser-ablation-ICP-MS.
A novel sample preparation method was utilized, allowing the analysis
of whole, intact daphnids, which facilitated the localization of silver
material and prevented artifacts. The results revealed that, despite
the similar ecotoxicity of the silver fibers, the amount of silver
associated with the neonates differed by a factor of 2–3. However,
both types of nanofibers were primarily found in the gut of the organisms.
In conclusion, the findings of this study do not support the expectation
that the morphology or size of silver materials affect their toxicity
to D. magna.