Resumo

Silver nanoparticles have attracted interest in biomedical engineering because of their antimicrobial properties against not only gram-positive but also gram-negative bacteria. Various poly(ethylene oxide)-poly(propylene oxide) block copolymers are known to enhance the activity of different antibacterial and antifungal drugs. Furthermore, studies suggest that these polymers show a broad spectrum of biological response - modifying activities. In this way, this class of polymers is one of the most potent drug targeting systems available, which has a remarkable impact on the emergent field of nanomedicine. The aim of this work was to evaluate the influence of one such polymer, commercially available as Pluronic ^® F68, on the antimicrobial activity of Silver nanoparticles. The Silver nanoparticles were produced by chemical reduction of silver nitrate with sodium citrate at 90°C. They were stabilized with the following polymers (i) PVP, (ii) PVA, (iii) PVP with pluronic and (iv) PVA with pluronic. The susceptibly tests were performed using the minimal inhibitory concentration method (MIC) against Pseudomonas aeruginosa ATCC 9721, in TSB broth in 24-wells microplates. These experiments were carried out at 37°C during 24 hours. For Silver nanoparticles stabilized with PVP, it was found that the presence of pluronic promoted a decrease of MIC values from 12.5% to 6.25%. However, for PVP-stabilized Silver nanoparticles, the necessary amount of Silver nanoparticles to promote the microorganism death was 16 fold higher with pluronic than without it. In this way, pluronic could be a promising enhancement agent for PVA-stabilized Silver nanoparticles. More assays should be delineated with other microorganisms before this combination can find therapeutic application in medical devices