Silver Nanoparticles at Biocompatible Dosage Synergistically Increases Bacterial Susceptibility to Antibiotics

Abstract

Antibiotics used to treat bacterial infections can become ineffective over time or result in the emergence of antibiotic resistant pathogens. With the advent of nanotechnology, silver nanoparticles (AgNPs) have gained significant attention as a therapeutic agent due to the well-known antimicrobial properties of silver. However, there are concerns and limited literature on the potential cytotoxicity of nanoparticles at effective antimicrobial concentrations. AgNPs prepared from silver nitrate with glucose reduction were characterized by surface plasmon resonance, dynamic light scattering, zeta potential analysis and transmission electron microscopy. The cytotoxicity of AgNPs towards human gingival fibroblasts over 7 days was determined using cell proliferation assays and confocal microscopy. AgNP MIC and antibacterial effects alone and in combination with 11 antibiotics were determined against a panel of nine microbial species including gram-positive and gram-negative bacterial species. AgNPs concentrations ≤ 1 µg/mL were non-cytotoxic but also showed no antibacterial effects. However, when combined with each of eleven antibiotics, the biocompatible concentration of AgNPs (1 µg/mL) resulted in significant inhibition of bacterial growth for multiple bacterial species that were resistant to either the antibiotics or AgNPs alone. This study presents a promising strategy with further testing in vivo, to develop novel antimicrobial agents and strategies to confront emerging antimicrobial resistance.

Tannic Acid-Stabilized Silver Nanoparticles Used in Biomedical Application as an Effective Antimelioidosis and Prolonged Efflux Pump Inhibitor against Melioidosis Causative Pathogen

“…AgNPs possess lower antibacterial concentration than those of LL-37 because AgNPs act as a nonspecific multimodal mechanism of action both insight and outsight of the bacterial cells. Thus, this advantage allows their effective antibacterial action at very low concentrations [ 44 , 45 ]. On the other hand, LL-37 is a cationic peptide, and the biological function of this peptide has been debated in several studies [ 3 , 46 , 47 ].…”

The Antibacterial and Remineralizing Effects of Biomaterials Combined with DMAHDM Nanocomposite: A Systematic Review

“…Despite the interdisciplinary role AgNP has in modern medicine, recent reviews have discussed the possible environmental and economic impacts of AgNPs that are synthesized either naturally (green synthesis) or chemically [ 55 , 56 , 57 , 58 ]. Moreover, development of AgNPs using the biological method of synthesis with the use of bacteria, fungi and plant extracts [ 55 , 56 ] have shown to be ecofriendlier, cost effective and energy efficient [ 59 ], with reports of greater antimicrobial activity against pathogenic bacteria [ 55 ].…”

The Potential Translational Applications of Nanoparticles in Endodontics

“…By electrostatically interacting with cell membranes and binding to thiol groups of proteins, AgNPs are able to disrupt cell walls and metabolic processes, inactivate bacterial enzymes, increase cell permeability and generate reactive oxygen species. 7 , 32 More recently, it has been shown that AgNPs could not only improve the antifungal effects of antifungal agents, but also enhance antibacterial effects of antibiotics against a range of bacteria, including antibiotic resistant strains. 33 , 34 The synergistic and multimode antibacterial actions substantially decrease the need for high doses of antibiotics, therefore minimizing the potential of antibiotic resistance and toxicity to the neighbouring tissues.…”

“…58 , 59 This includes, but is not limited to, the average diameter, zeta potential, surface plasmon resonance peak and concentration. 32 , 35 , 36 , 57 A full list of the key physicochemical properties of nanomaterials can be found in Table 1 . 59 For example, Abbaszadegan et al provided a comprehensive characterization of the synthesized AgNPs with negative, neutral and positive surface charges, reporting the plasmon resonance peak was 400 nm, 425 nm and 407 nm, average size was 7.5 nm, 10.1 nm and 9.0 nm, concentration was 9.7 x 10 −8 mol L −1 , 4.0 x 10 −8 mol L −1 and 5.7 x 10 −8 mol L −1 and zeta potential was −38.0 mV, 0.0 mV and +50.0 mV respectively.…”