Comparative Cytotoxicological Study of Ionic Silver and Silver Nanoparticles Using an MTT Bioassay

Abstract

<p>The development and deployment of nanomaterials for consumer applications is underway. In fact, 54% of the nanomaterials in commercial use contain silver due to its antimicrobial or oligomeric properties. Yet, 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 use in comparative toxicological studies. Colloidal AgNPs were produced using a modified Creighton method by the reduction of silver nitrate with sodium borohydride. The physico-chemical properties of AgNPs were characterized to confirm 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). EPA and other organizations have recently established these parameters as being critical for the comparison between various cytotoxicity studies. Tangential flow ultrafiltration was employed to size-select AgNPs (20 nm diameter and smaller) and to concentrate them (larger than 10-fold) in a small volume of water with minimal aggregation for cellular dosage. Vero 76 monkey kidney cells were exposed to varying concentrations of ionic silver (Ag+) and nonionic AgNPs ranging from 0 to 500 ppm. MIT, an in vitro bioassay, was used to measure the cellular metabolic function of Vero 76 cells and to determine the median lethal dose of Ag+ (LD50 in between 28 and 40 ppm). 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>