Abstract
The toxicity towards viruses of silver nanoparticles (AgNPs) has been reported to be dependent on several factors such as particle concentration, size, and shape. Although these factors may indeed contribute to the toxicity of AgNPs, the results presented in this work demonstrate that surface chemistry and especially surface charge is a crucial factor governing their antiviral activity. Here, this work investigated the influence of capping agents representing various surface charges ranging from negative to positive. These AgNPs were capped with citrate, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) mercaptoacetic acid (MAA) and (branched polyethyleneimine (BPEI). We show that AgNPs exhibited surface charge-dependent toxicity towards MS2 bacteriophages. Among the capping agents under investigation, BPEI capped AgNPs (Ag/BPEI) exhibited the highest reduction of MS2 resulting in ≥6 log10-units reductions, followed by 4–5 log10-units reductions with PVP and PEG capping’s and 3–4 log10-units with MAA and citrate cappings. Bare nanoparticles reported a mere 1–2 log10-units reduction. Electrostatic interaction between the positively charged BPEI-coating and the negatively charged virus surface played a significant role in bringing the MS2 closer to toxic silver ions (Ag+). Further results obtained from TEM showed that Ag/BPEI nanoparticles could directly damage the structure of the MS2 bacteriophages. AgNPs and cationic capping agents’ observed synergy can lead to much lower and much more efficient dosing of AgNPs for antiviral applications.
Highlights
Infectious diseases are responsible for more than 20% of global mortality, and one of the leading causes of suchNanotechnology 32 (2021) 365101 diseases are viruses, accounting for about one-third of these deaths [1]
The toxicity towards viruses of silver nanoparticles (AgNPs) has been reported to be dependent on several factors such as particle concentration, size, and shape. These factors may contribute to the toxicity of AgNPs, the results presented in this work demonstrate that surface chemistry and especially surface charge is a crucial factor governing their antiviral activity
We investigate the antiviral activity of AgNPs capped with several capping agents namely, branched polyethyleneimine (Ag/BPEI), mercaptoacetic acid (Ag/ MAA), citrate (Ag/Citrate), polyethylene glycol (Ag/PEG) and polyvinylpyrrolidone (Ag/PVP) against MS2 bacteriophages
Summary
Infectious diseases are responsible for more than 20% of global mortality, and one of the leading causes of such. Given the significant effect of capping agents on the toxicity towards bacteria and the other nanoparticles’ properties, it becomes vital to understand the impact of a capping agent on metallic nanoparticles’ antiviral activity. Such nanoparticles could act as broad-spectrum antivirals while still being non-toxic to humans [5, 30]. MS2’s properties, such as morphology and survival in the environment, have been likened to many enteric viruses Due to these reasons, MS2 has been used as a surrogate for pathogenic enteroviruses for disinfection testing on surfaces, in water and food; modelling the movement and survival of pathogens in different environments, and transfer properties from surfaces. While the focus is on the effect as a stabiliser, the additional effects of change in nanoparticle stock concentration, exposure time and NP size on reducing the viral titre of MS2 were investigated as a comparison
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