Abstract: 
Nanosilver is an antibacterial agent that can inhibit the growth of gram-positive bacteria such as Staphylococcus aureus. The small size makes nanosilver enhance its antibacterial properties. Nanosilver can be used as an active ingredient in topical preparations such as gels. In this study, the aim was to formulate and determine the antibacterial activity of gel nanosilver against Staphylococcus aureus. Synthesis nanosilver uses a reduction method with reducing sodium citrate and gelatin stabilizer. The Nanosilver synthesized was then characterized by UV-Vis and spectrophotometers Particle Size Analyzer (PSA). Gel preparations were nanosilver made from carbopol 940 with various concentrations of nanosilver which were 1.5%, 2%, and 2.5% which were physicochemically evaluated including organoleptic, pH, homogeneity, dispersion, viscosity, centrifugation, and cycling test at 4^oC and 40^oC. The antibacterial activity test was carried out by the excellent diffusion method using Nutrient Agar (NA) solid media with an incubation time of 1×24 hours at 37^oC. The test bacteria used was Staphylococcus aureus. Based on the data obtained showed that the gel preparation nanosilver had physicochemical characteristics which were both organoleptically clear transparent, odorless, semisolid form, had a pH range of 5.63-5.76, homogeneous, spread power 3.3-3.83 cm, viscosity 2017-2500 cP and stocks remain stable during the period of storage and cycling test. Variations in the concentration of nanosilver in gel preparations can have an effect on inhibiting the growth of bacteria Staphylococcus aureus with inhibition by Formula 1 (1.5%) of 4.467 ± 0.275 mm, Formula 2 (2%) of 5.683 ± 0.475 mm, and Formula 3 (2, 5%) of 6.483 ± 0.425 mm.

Keywords: Nanosilver, Nanoparticle Synthesis, Gel, Formulation, Antibacterial, Formulation.