Abstract
The advancement of nanotechnology has increased use of nanoparticles in
industrial scale. Among the most used nanoparticles are those
silver-based. Large-scale use can raise levels of these nanoparticles in
aquatic environments, which, in turn, presents potential risks to
aquatic organisms and ecosystems, causing undesired environmental
impacts. To evaluate the potential risk of the silver nanoparticles
(AgNPs) interaction with plants, seeds of Lactuca sativa L. (Asteraceae)
were exposed to different concentrations of AgNPs (12.5, 25, 50, 100
ppm), using the percentage of germinated seeds and morphological changes
in the root as toxicity criterion. Only at the maximum concentration of
AgNPs (100 ppm), there is a negative effect on root growth in relation
to the positive control (distilled water). These negative effects may be
related to the production of reactive oxygen species (ROS) caused by the
dissolution of Ag-0 in Ag+. Other concentrations had a positive effect
on root growth, although not significant. Scanning electron microscopy
(SEM) images showed morphological changes in the root surface exposed to
the concentration of 100 ppm of AgNPs, resulting in root deformation.
The accumulation of silver nanoparticles (AgNPs) was observed using
transmission electron microscopy (TEM). AgNPs were found in the
vacuoles, cell wall, middle lamella and cytoplasm, individualised or
forming agglomerates. These results broaden our understanding of the
safe levels of nanoparticle use and its impact on the environment. In
addition, the nanoparticles used in this study can be used in new
product development, since the observed maximum safe amount.
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