Surface functionalized silver nanoparticles augment macrophage activation followed by intracellular killing of pathogenic bacteria

Nanoparticles interact with these immune cells and modulate its function, leading to immunosuppression or immunostimulation. The immunostimulatory activity of modified metal nanoparticles is based on the activation of immune system against pathogenic bacteria. In this study, we evaluate the efficacy of modified metal nanoparticles to activate immune cells (Macrophage) and also to examine the efficacy of those activated macrophages towards intracellular killing of pathogenic S. aureus and P. aeruginosa bacterial strains. Synthesized Ag-NPs were modified by polyethylene glycol (PEG). The modified nanoparticles successfully activated macrophage (MФ) evident by the increasing the serum TNF-α level and intracellular NO generation. To check the effective contribution of TNF-α and COX-2 pathway underlying the Ag@PEG NPs pulsed macrophage induced bacterial killing addition of POF and ASA in co-culture setup was done. PEG functionalized nanoparticles enhanced the intracellular killing of pathogenic bacteria in macrophage. We also found that, Ag@PEG NPs pulsed RAW 264.7 secreted elevated level of proinflammatory cytokines. Pulse macrophages were also successfully killed intracellular pathogenic S. aureus and P. aeruginosa bacteria in in vitro setup at 1:1 ratio for 24 h. The use of TNF-α inhibitor and NO blocker confirmed the association between Ag@PEG NPs with TNF-α and NO function. These findings will enrich the biomedical applications of Ag@PEG NPs as a potent immune stimulating agent and this macrophage stimulating efficacy might be an effective way in the bacterial immunotherapy. Such a metal nanoparticles offers versatility in that it can simultaneously activate the primary Immune cells as well as kill the ingested microbes.