Cytotoxicological study of Creighton colloidal silver nanoparticles in Vero 76 monkey kidney cells

Abstract

<p>Silver ionic has been used since ancient times due to its antimicrobial and oligomeric properties. Nowadays, with the advancement of nanoscience and nanotechnology, silver nanomaterials find numerous commercial and research applications. However, little is known about the cytotoxicity of silver nanomaterials, in particular silver nanoparticles (AgNPs). In this study, non-ionic AgNPs were synthesized, characterized, and size-selected for cytotoxicological studies. Colloidal AgNPs were prepared using a modified Creighton method by the reduction of silver nitrate with sodium borohydride. The physical and chemical properties of AgNPs showed the size and shape distribution (TEM, UV-Vis absorption spectrophotometry), surface functionalization and charge (reaction mechanism), aggregation state (TEM), concentration (flame atomic absorption spectrophotometry), and purity (Raman spectroscopy). The U.S. Environmental Protection Agency and other organizations have indicated that these parameters must be reported in cytoxicity studies. A tangential flow ultrafiltration process was employed to sizeselect AgNPs (20 nm diameter and smaller) and to concentrate them in a small volume of water (from 10 L to 2 mL suspension) with minimal aggregation for cellular dosage. Vero 76 monkey kidney cells were exposed to varying concentrations of control ionic silver (Ag+) and nonionic AgNPs treatment ranging from 4 to 512 ppm. The following control samples were also included: untreated cells, sodium borohydride and vehicle. Flame atomic absorption spectroscopy measurements verified the silver content for both silver ionic and AgNP cell treatments. MIT, an in vitro bioassay, was used to measure the metabolic function of Vero 76 cells and to determine the median lethal dose (LD50) of silver ionic and nonionic AgNPs. LD50 of silver ionic was calculated at 31.9 ppm using the Karber formula. Undergoing studies in our group will establish the LD50 of AgNPs. Preliminary results indicate AgNPs as being at least 2-fold less cytotoxic than the ionic silver.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 8, 2011</p>