Enhancement of Antibacterial Activity of Capped Silver Nanoparticles in Combination with Antibiotics, on Model Gram-Negative and Gram-Positive Bacteria
The nanoparticles used in this study were prepared from AgNO3 using NaBH4 in the presence of capping agents such as citrate, sodium dodecyl sulfate, and polyvinylpyrrolidone. The formed nanoparticles were characterized with UV-Vis, TEM, and XRD. The generation of silver nanoparticles was confirmed from the appearance of yellow colour and an absorption maximum between 399 and 404？nm. The produced nanoparticles were found to be spherical in shape and polydisperse. For citrate, SDS, and PVP capped nanoparticles, the average particle sizes were , , and ？nm, respectively. The crystallinity of the nanoparticles in FCC structure is confirmed from the SAED and XRD patterns. Also, the combined antibacterial activity of these differently capped nanoparticles with selected antibiotics (streptomycin, ampicillin, and tetracycline) was evaluated on model Gram-negative and Gram-positive bacteria, employing disc diffusion assay. The activity of the tested antibiotics was enhanced in combination with all the stabilized nanoparticles, against both the Gram classes of bacteria. The combined effects of silver nanoparticles and antibiotics were more prominent with PVP capped nanoparticles as compared to citrate and SDS capped ones. The results of this study demonstrate potential therapeutic applications of silver nanoparticles in combination with antibiotics. 1. Introduction Since ancient times, silver has been known to possess antibacterial properties [1], but the solubility characteristics of silver metal and silver salts (e.g., silver nitrate) render it impractical in many clinical scenarios, that is, where silver nanoparticles (Ag NPs) have been a subject of great interest among researchers [2–4], because it is not only facile to synthesize silver nanoparticles of desired sizes [5, 6] and shapes [7–9] dispersed in aqueous/organic phases but also feasible to make films, with the composite of these particles suiting various applications in the field of medical diagnosis and therapy. The use of silver nanoparticles in materials modification for application in different fields such as clothing, semiconductor, and preparation of nanocomposite materials with improved performances has been demonstrated. For example, silver nanoparticles have been successfully coated on medical devices for infection-free transplantation [10, 11]. Silver nanoparticles have also been coated on various fabrics [12–15]; the coating of nanosilver imparts not only the metallic feature to the fibers rendering the textiles conductive but also the antibacterial property to the textiles. These studies
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