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, 46 nm and unmodified 10-65 nm AgNPs using murine 291.03C keratinocyte and RAW 264.7 monocyte cell lines. Both cell lines exposed for 24h to 1-10 μg/ml of 13 nm, 33 nm, 46 nm 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, 46 nm and 10-65 nm AgNPs in cytoplasmic vacuoles, whereas keratinocytes accumulated less particles. AgNPs of 13 nm 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 30 nm suggests that tannic acid modification of large silver nanoparticles may help to increase AgNPs biosafety.
Keywords: Keratinocytes; Monocytes; Silver nanoparticles; Tannic acid.
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