heal.abstract |
Nanoparticles have unique physiochemical properties compared to the bulk material comprising them, which make them preferable in a variety of applications including bioimaging, drug delivery and food packaging. These properties depend on the nanoparticles’ morphology. Silver nanoparticles (AgNPs) have been especially distinguished for their antimicrobial efficacy against both Gram-negative and Gram-positive bacteria. However, the mechanism of their antimicrobial action has not yet been fully understood. Although their antimicrobial properties are very tempting and they are already used in a variety of consumer products, there is still worldwide concern regarding their cytotoxicity.
Bearing these unresolved issues in mind, in the present study, synthesis of AgNPs was achieved with the aim of producing different sizes and/or different shapes of nanoparticles to subsequently test their antimicrobial efficacy and their possible cytotoxicity effects. Modified Turkevich Methods and Reduction via plasma generation were used for AgNPs synthesis. Salmonella enterica and Normal Human Dermal Fibroblasts (NHDF) were used for the antimicrobial and cytotoxicity testing accordingly.
The results of the experiment demonstrated that all AgNPs dispersions inhibited Salmonella enterica at both concentrations tested (6.2 and 3.9 ppm), at 0-6 h exposure time, but the most antimicrobial one was the one produced by plasma reduction, which inhibited Salmonella enterica even at 0.39 ppm, followed by the one synthesized by Modified Turkevich Method at 70oC with 1:10 molar ratio of AgNO3 to Na3C6H5O7. Nevertheless, all AgNPs also reduced Fibroblasts viability, at 3 days exposure time, at these concentrations tested on Salmonella enterica. The reduction of cells viability seemed to be concentration-dependent (except AgNPs synthesized by Modified Turkevich Method at room temperature with 1:10 molar ratio) and time-dependent. Most AgNPs samples did not present strong cytotoxicity effects only at low concentrations (e.g., 0.49 and 0.98 ppm), except AgNPs synthesized by plasma reduction that were found toxic on the first 2 days of exposure even at 0.39 ppm. Also, the obtained IC50 values of all samples were low (< 100 ppm). The smallest IC50 value in particular, derived from the smallest (7-15 nm) and spherical nanoparticles. Last but not least, AgNPs seem to be equally toxic and perhaps follow the same cytotoxicity action with AgNO3 on the 1st day of exposure and at high concentrations (3.9 and 6.2 ppm), whereas after 24 h exposure, AgNPs of the same concentration, appear to be more toxic than AgNO3. Therefore, more cytotoxicity studies are needed for their possible future use in health-related applications. |
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