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Jedinstvena antibakterijska svojstva srebra su poznata još od vremena egipatskih faraona. Otkrićem antibiotika početkom dvadesetog stoljeća srebro je uglavnom istisnuto iz uobičajene upotrebe u medicini. Prekomjernom upotrebom antibiotika pojavile su se superbakterije koje su stvorile otpornost na antibiotike, stoga je povećan interes za proučavanje antibakterijskih djelovanja koloidnog srebra. U ovom radu istražen je utjecaj različitih koncentracija srebrovog nitrata na stvaranje koloidnih čestica srebra u otopini. Koloidno srebro je pripremljeno metodom kemijskog taloženja pomoću natrijeva borohidrida. Za karakterizaciju dobivenih koloida su korišteni boja otopine, Tyndallov efekt, apsorpcija UV/Vis zračenja te veličina čestica koja je procijenjena PWHM i Mie metodom. Boja otopina je s porastom koncentracije srebra varirala od žute do tamno smeđe. Sve otopine su podjednako pokazivale Tyndallov efekt. UV/Vis spektrofotometrom je ustanovljeno da otopine apsorbiraju zračenje valnih duljina 390- 402 nm, a intenzitet opada s porastom koncentracije. PWHM i Mie metodom procijenjeno je da otopine sadrže čestice srebra veličine 12-20 nm. Unique antibacterial properties of silver have been known since the time of Egyptian pharaohs. With the discovery of antibiotics at the beginning of the twentieth century silver is mostly pushed out from the conventional medicine. With excessive use of antibiotics, superbugs have emerged that developed resistance to antibiotics. Therefore, there is an increased interest in studying the antibacterial effects of colloidal silver. In this paper, the influence of various concentrations of silver nitrate on the formation of colloidal silver particles in the solution was investigated. Colloidal silver was prepared by a chemical precipitation method using sodium borohydride. For characterization of the obtained colloids were used color of the solution, Tyndall effect, UV/Vis absorption and particle size which was estimated by PWHM and Mie method. The color of the solution is with the increase in the concentration of silver varied from yellow to dark orange. All solutions showed Tyndall's effect equally. The UV/Vis spectrophotometer determined that the solutions absorb wavelengths of 390-402 nm and intensity decreased with increase of concentration. With PWHM and Mie method was estimated that the solutions contain silver particles of 12-20 nm. |
