Cytogenetic effects of chitosan-capped silver nanoparticles in the Allium cepa test

Silver nanoparticles are one of the most commonly used nanomaterials. However, there remains insufficient information on their genotoxic effects. The goal of this study was to investigate cytotoxic and genotoxic effects of chitosan-coated AgNPs using the well-established Allium test. Root tip cells were treated with solutions at different concentrations (1, 2.5, 5 and 50 mg l−1) of chitosan-coated AgNP (size: 10–30 nm; organic coat: 2–5 nm). On the same slide mitotic abnormalities, chromosome aberrations and micronuclei were detected. Also mitotic and phase indexes were analyzed. No cytotoxic or genotoxic effects were found at concentrations below 5 mg l−1. The absence of induction of chromosomal and mitotic abnormalities by chitosan-capped AgNPs at low concentrations is possibly due to the capping, which may partly protect the cells from direct interaction with the AgNPs. Mitotic and chromosomal abnormalities and micronuclei were detected at a concentration of 50 mg l−1. Significant increase in mitotic index was found at 5 and 50 mg l−1 concentrations of AgNP. The data demonstrated that chitosan-coated AgNP exhibit both clastogenic and aneugenic activity.