In vitro efficacy and toxicology evaluation of silver nanoparticle-loaded gelatin hydrogel pads as antibacterial wound dressings

The silver nanoparticle (nAg)-loaded gelatin hydrogel pads were prepared from 10 wt % gelatin aqueous solution containing silver nitrate (AgNO3) at 0.75, 1.0, 1.5, 2.0, or 2.5 wt % by solvent-casting technique. These AgNO3-containing gelatin solutions, that had been aged for 15, 12, 8, 8, and 8 h, respectively, showed noticeable amounts of the as-formed nAgs, the size of which increased with an increase in the AgNO3 concentration (i.e., from 7.7 to 10.8 nm, on average). The hydrogels were crosslinked with a glutaraldehyde aqueous solution (50 wt %, at 1 mu L mL(-1)). At 24 h of submersion in phosphate buffer saline (PBS) or simulated body fluid buffer (SBF) solution, about 40.5-56.4% or 44.4-79.6% of the as-loaded amounts of silver was released. Based on the colony count method, these nAg-loaded hydrogels were effective against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, with at least about 99.7% of bacterial growth inhibition. Unless they had been treated with a sodium metabisulfite aqueous solution, these hydrogels were proven, based on the indirect cytotoxicity evaluation, to be toxic to human's normal skin fibroblasts. Lastly, only the hydrogels that contained AgNO3 at 0.75 and 1.0 wt % were not detrimental to the skin cells that had been cultured directly on them. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012