Physicochemical Characterization and Antimicrobial Activity of Nanosilver Containing Hydrogels

Silver ion has been used for centuries to prevent and treat a variety of diseases and infections. In recent years, extensive studies have been undertaken on the use of antimicrobial properties of silver, incorporated within medical devices. The aim of this study was to prepare a formulation containing silver ion, which could be applied for wound dressing. The purity of nanosilver was measured by atomic absorption spectrophotometer. The purity was determined to be 96.80 % ±0.01. The "serial dilution method" was used to determine the Minimum Inhibitory Concentration (MIC) of nanosilver, on microorganisms such as staphylococcus aureus, and Pseudomonas aeruginosa. The MIC of nanosilver solution was 15.12 µg/ml. In order to design a hydrogel formulation, different formulations, using HPMC K15M, were made. Next, the best formulation (at 2% w/w) was selected, based on attractiveness, homogeneity and flexibility. This formulation was used for the preparation of the next formulations, containing various percentages of two types of plasticizer. Again, the best formulation was chosen. In order to increase the thickness and resistance of the film, another polymer (HPMC K100 or agar), was added to the formulation. For evaluation of the prepared films, different tests including determination of thickness and tensile strength, swelling and water vapor transition were performed. Finally, the best formulation containing 2% w/w HPMC K15M, 0.5% w/w HPMC K100 and 0.2% triacetin (as plasticizer)was selected. Then, various concentrations of nanosilver solution were added to the selected formulation. In this manner, the most suitable concentration of nanosilver (4 mg in an area of 100 cm2 or almost 1.5 g weight), which had the best antimicrobial effect in the hydrogel films was detected. In the final stage, the amount of silver in the final film was determined by atomic absorption spectrophotometer. The obtained result confirmed the amount of silver in the final film.