Mechanistic Basis of Antimicrobial Actions of Silver Nanoparticles

Abstract

Multidrug resistance of the pathogenic microorganisms to the antimicrobial drugs has become a major impediment toward successful diagnosis and management of infectious diseases. Recent advancements in nanotechnology-based medicines have opened new horizons for combating multidrug resistance in microorganisms. In particular, the use of silver nanoparticles (AgNPs) as a potent antibacterial agent has received much attention. The most critical physico-chemical parameters that affect the antimicrobial potential of AgNPs include size, shape, surface charge, concentration and colloidal state. AgNPs exhibits their antimicrobial potential through multifaceted mechanisms. AgNPs adhesion to microbial cells, penetration inside the cells, ROS and free radical generation, and modulation of microbial signal transduction pathways have been recognized as the most prominent modes of antimicrobial action. On the other side, AgNPs exposure to human cells induces cytotoxicity, genotoxicity, and inflammatory response in human cells in a cell-type dependent manner. This has raised concerns regarding use of AgNPs in therapeutics and drug delivery. We have summarized the emerging endeavors that address current challenges in relation to safe use of AgNPs in therapeutics and drug delivery platforms. Based on research done so far, we believe that AgNPs can be engineered so as to increase their efficacy, stability, specificity, biosafety and biocompatibility. In this regard, three perspectives research directions have been suggested that include (1) synthesizing AgNPs with controlled physico-chemical properties, (2) examining microbial development of resistance toward AgNPs, and (3) ascertaining the susceptibility of cytoxicity, genotoxicity, and inflammatory response to human cells upon AgNPs exposure.

Nanomaterials for alternative antibacterial therapy

“…Ag NPs are the most effective nano-weapon against bacterial infections. [28][29][30] On the other hand, upsurge in resistance to Ag NPs has been reported due to genetic alterations in bacteria. 31 The deposition of silver 32 The high toxicity of CuO NPs causes oxidative lesions, while DNA damage induced by ZnO and TiO 2 NPs limits the efficacy of these NPs.…”

Antimicrobial Performance of Thermoplastic Elastomers Containing Zinc Pyrithione and Silver Nanoparticles

“…One of the mechanisms of silver ion release from polymeric matrix occurs through contact of metallic silver with dissolved oxygen in moisture 15,16 . Once released, AgNano will act on the microbial cells through several modes of action 17 , such as: (a) nanoparticles can bind to proteins of vital enzymes presents in the mycelial 18 and bacterial 19 cell wall, (b) also can damage the cellular structures and biomolecules 20 , (c) cause toxicity by the generation of reactive oxygen species 21 , besides (d) affecting in the molecular and cellular routes of bacteria. Recently, silver nanoparticles have been pointed out as the most innovative and efficient antibacterial form 16 , since they provide better dispersion in the polymeric matrix 22 .…”

Silver Nanoparticles-Loaded Exfoliated Graphite and Its Anti-Bacterial Performance

“…The antimicrobial mechanism of silver nanoparticles is not completely understood. The most accepted mechanism is related to the fact that silver nanoparticles can release Ag + ions, which may affect the metabolic processes and the mechanism of cell division, causing serious problems in the membrane permeability, resulting in the death of the bacteria [40,41]. …”