Assessment of in vitro cellular responses of monocytes and keratinocytes to tannic acid modified silver nanoparticles

Abstract

Hydrolyzable tannins are known to exhibit diverse biological effects, which can be used in combination with silver nanoparticles (AgNPs). In this study, we tested toxic and inflammatory properties of tannic-acid modified 13, 33, 46nm and unmodified 10–65nm AgNPs using murine 291.03C keratinocyte and RAW 264.7 monocyte cell lines. Both cell lines exposed for 24h to 1–10μg/ml of 13nm, 33nm, 46nm and unmodified AgNPs showed dose-dependent toxicity and decreased cell proliferation. Only small-sized AgNPs induced production of ROS by monocytes, but not keratinocytes. Monocytes internalized large aggregates of 33, 46nm and 10–65nm AgNPs in cytoplasmic vacuoles, whereas keratinocytes accumulated less particles. AgNPs of 13nm were localized ubiquitously within both cell types. The tested AgNPs strongly down-regulated production of tumor necrosis factor-α (TNF-α) by monocytes, whereas keratinocytes exposed to AgNPs showed an opposite effect. Unmodified but not tannic acid-modified AgNPs increased production of the pro-inflammatory MCP-1 by monocytes and keratinocytes. In summary, low inflammatory potential and lack of ROS production by tannic-acid modified AgNPs sized above 30nm suggests that tannic acid modification of large silver nanoparticles may help to increase AgNPs biosafety.