Silver nanoparticles and silver salts: internal concentration and behavioural effects on marine amphipods

Author(s)

Monizze Vannuci Silva

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2018-06-25

Examining board members

Gisela de Aragão Umbuzeiro; Silvana Gomes Leite Siqueira; Clarice Maria Rispoli Botta; Maurea Nicoletti Flynn; Vicente Gomes

• Advisor: Solange Cadore; Gisela de Aragão Umbuzeiro

Abstract

Silver has been incorporated in nanomaterials due to its broad-spectrum antibacterial property and, consequently, it has been released into the environment in worrying amounts. Silver effects in marine organisms, especially as nanoparticles, are not totally known yet. Among marine organisms, amphipods are widely distributed and an important ecological link in their ecosystems. The aims of this work were to develop and to apply methodologies to determine silver internal concentration ¿ present in the haemolymph ¿ and to evaluate behavioural alterations in marine amphipods when they are exposed to silver nanoparticles (AgNP) and silver salts via water and via feeding. Methods to determine silver in the haemolymph were successfully developed and applied in exposure experiments using the tropical marine amphipod Parhyale hawaiensis. Silver absorption was proportional to the exposure time and silver concentration in water, ranging from 0.4 ng mg-1 to 13 ng mg-1. However, Ag concentration was regulated in a time/concentration-dependent way, since no significant increase of Ag in the haemolymph was observed for a same concentration after 48 of exposure, neither between the concentrations of 50 and 100 µg L-1. In the feeding exposure, absorption rate of silver was 2.8 times higher when the organisms were exposed to AgNP than AgCl, suggesting that nanoparticles were absorbed by the organisms and distributed in the haemolymph, possibly releasing ionic silver (Ag+) after their internalization; or that the NPs were trapped in the gut, releasing Ag+ over time, even after feeding period. The evaluation of the swimming behaviour was studied in the marine amphipod from temperate zones, Echinogammarus marinus, exposed to the same concentrations and for the same period as P. hawaiensis. This behavioural endpoint was relevant for metal exposure studies, once significant behavioural alterations in swimming velocity in response to light were observed for exposure via water. The present work provides new tools and information that contribute to the understanding of the effects and potential risks of Ag from AgNP released in the environment (AU)

• FAPESP's process: 13/26301-7 - Development and application of method for silver determination in the hemolymph of amphipods exposed to nanomaterials
• Grantee: Monizze Vannuci e Silva
• Support Opportunities: Scholarships in Brazil - Doctorate