Modulation by surroundings of the antibacterial efficiency of silver in water environments

Abstract

Silver is a usual antibacterial agent acting in water solutions. However, quantitative data fail to anticipate the silver availability for interactions with bacterial cells and the resulting fluctuations of the inhibitory and bactericidal concentrations according to silver amount and chemical composition of the liquid environment. We investigated whether and how three different biological media modify silver ions (Ag + ) and nanoparticles (AgNPs), and alter their antibacterial performances against Escherichia coli K12. The predominant silver species highly differed in terms of nature and quantity according to the medium. Bioavailability was reduced to a few percent of the initial Ag + amount in physiological serum (NaCl) and lysogeny-broth (LB), while it was higher than 67% in minimal phosphate medium (M63G). To reach similar antibacterial performances, Ag + concentrations were 100 times lower in M63G than in the other media. Even with a silver concentration of 10 -1 M, 53% of the bacterial cells living after 3h in LB were undamaged and revealed normal metabolic activity, while the cells were almost completely eliminated in M63G. Effects of AgNPs were also strongly but differently modulated by the medium's components. AgNPs revealed higher antibacterial effect than Ag + in NaCl and M63G with similar silver content, thus providing an argument to assert that AgNPs act through a combination of release of Ag + and intake of AgNPs. Our results finally provide guidelines about the Ag + dose that must be released from coatings to reach efficient performances according to the surrounding medium and the framework of the study.

Bio-sourced phosphoprotein-based synthesis of silver-doped macroporous zinc phosphates and their antibacterial properties

“…In particular, the bacterial strain, culture medium and temperature are parameters known to affect bacterial sensitivity to antibacterial agents. 62,63 Thus, reported studies 64,65 and results obtained by our group using M63G culture medium 66 have shown that the interactions of Ag + ions with compounds in different media reduce the amount of Ag + available for antibacterial action. Despite these interactions, however, the results reported here demonstrate that Ag + ions were released from the ZnPOs/Ag-750 material in sufficient amounts to affect both bacterial colonization and proliferation and therefore to endow it with antibacterial properties.…”

Antimicrobial and mechanical properties of functionalized textile by nanoarchitectured photoinduced Ag@polymer coating

“…This leads to the leakage of cellular components through the pores of the perforated cellular membrane. Once inside, the ions promote reactive oxygen species (ROS) generation, deactivate proteins, and block DNA replication [ 21 ]. Silver nanoparticles (AgNPs) have the added benefit of being ionic silver vessels, combining the latter’s antimicrobial properties with their own characteristics [ 16 ].…”