Effects of Sub-lethal Concentrations of Silver Nanoparticles on a Simulated Intestinal Prokaryotic–Eukaryotic Interface

Abstract

Nanotechnology applications are expected to bring a range of benefits to the food sector, aiming to provide better quality and conservation. In this research, the physiological response of both an Escherichia coli mono-species biofilm and Caco-2 intestinal cells to sub-lethal concentrations of silver nanoparticles (AgNPs) has been investigated. In order to simulate the anaerobic and aerobic compartments required for bacteria and intestinal cells growth, a simplified semi-batch model based on a transwell permeable support was developed. Interaction between the two compartments was obtained by exposing Caco-2 intestinal cells to the metabolites secreted by E. coli biofilm after its exposure to AgNPs. To the best of the authors' knowledge, this study is the first to investigate the effect of AgNPs on Caco-2 cells that takes into consideration previous AgNP-intestinal biofilm interactions, and at concentrations mimicking real human exposure. Our data show that 1 µg/mL AgNPs in anaerobic conditions (i) promote biofilm formation up to 2.3 ± 0.3 fold in the first 72 h of treatment; (ii) increase reactive oxygen species (ROS) production to 84 ± 21% and change the physiological status of microbial cells after 96 h of treatment; (iii) seriously affect a 72-h old established biofilm, increasing the level of oxidative stress to 86 ± 21%. Moreover, the results indicate that oxygen renders the biofilm more adequate to counteract AgNP effects. Comet assays on Caco-2 cells demonstrated a protective role of biofilm against the genotoxic effect of 1 µg/mL AgNPs on intestinal epithelial cells.

Molecular Mechanisms of Bacterial Resistance to Metal and Metal Oxide Nanoparticles

“…This is due to the fact that under anaerobic conditions there is a lower production of ROS and although the nanoparticles affect the bacterium the lack of the deleterious mechanisms induced by ROS diminishes its bactericidal activity [64]. This is important since the use of nanoparticles to fight bacteria causing diseases in anaerobic environments could cause the adaptation of bacteria and changes in microbiomes that could aggravate the pathologies [65].…”

Synthesis of Pyrazolone Derivatives and Their Nanometer Ag(I) Complexes and Physicochemical, DNA Binding, Antitumor, and Theoretical Implementations

“…The spherical particles display λ max band at shorter wave length, while the nonspherical shape of particles shifts the λ max to longer wave length [ 41 ]. The higher the intensity of the complex color, the higher the concentration of AgNPs [ 42 ]. The tetrahedral configuration of Ag(I) complexes ( Figure 2 ) was proposed based on analytical, IR, 1 H, 13 C NMR, and mass spectral analysis, which is acceptable for d 10 systems.…”

Hindering the formation and promoting the dispersion of medical biofilms: non-lethal effects of seagrass extracts

“…E. coli biofilm was grown on a sterile polycarbonate membrane (PC, Whatman Nucleopore, diameter 2.5 cm, pore diameter 0.2 μm) as previously described by Garuglieri et al [ 42 ]. Briefly, 0.05 ml of an overnight culture (approximately 10 6 cells/ml) were inoculated at the center of a sterile polycarbonate membrane and, when the inoculum was completely dried, the membrane was carefully put inside a transwell structure (ThinCert™ Cell Culture Inserts with translucent PET membrane – Greiner bio-one) inlaid in a 6 well culture plate (Greiner bio-one).…”