Acute Toxicity of Silver Free and Encapsulated in Nanosized Zeolite for Eukaryotic Cells

The potential toxicity of encapsulated silver in EMT-type nanosized zeolites on prokaryotic cells, human tumor cell lines from various origins, and primary cultures of neurons and astrocytes was investigated. Silver in cationic form (Ag+) was encapsulated in EMT-type nanosized zeolites via an ion exchange process (Ag+-EMT) and compared with the reduced silver (Ag0) in the zeolite (Ag0-EMT). As reference samples for the toxicity measurements, pure EMT-type zeolite and silver perchlorate were used. Cells were exposed to silver-containing zeolites (50, 100, and 400 μg/mL) for 24 and 48 h. After exposure to Ag+-EMT (50 μg/mL) for 24 h, a loss in cell viability independent of the cell type was observed, ranging from −34.37 ± 23.90% for astrocytes to −99.5 ± 0.24% for U87-MG cells. These results were comparable with the toxicity for silver perchlorate. The Ag0-EMT sample showed lower toxicity on human cell lines in comparison to that of Ag+-EMT. A decrease in cell viability, i.e., −73.46 ± 20.78% and −62.3 ± 17...