The Potential of Silver Nanoparticles for Antiviral and Antibacterial Applications: A Mechanism of Action

Abstract

Rapid development of nanotechnology has been in high demand, especially for silver nanoparticles (AgNPs) since they have been proven to be useful in various fields such as medicine, textiles, and household appliances. AgNPs are very important because of their unique physicochemical and antimicrobial properties, with a myriad of activities that are applicable in various fields, including wound care management. This review aimed to elucidate the underlying mechanisms of AgNPs that are responsible for their antiviral properties and their antibacterial activity towards the microorganisms. AgNPs can be synthesized through three different methods-physical, chemical, and biological synthesis-as indicated in this review. The applications and limitations of the AgNPs such as their cytotoxicity towards humans and the environment, will be discussed. Based on the literature search obtained, the properties of AgNPs scrutinizing the antibacterial or antiviral effect shown different interaction towards bacteria which dependent on the synthesis processes followed by the morphological structure of AgNPs.

Keywords: antimicrobials; antiviral; cytotoxicity; mechanism of action; nanotechnology; silver nanoparticles.

1. Introduction

Silver (Ag) is a chemical element that has provided promising results in various fields such as medicine, electronics, and household applications, e.g., silver sulfadiazine has been used as a standard treatment for burn wounds to prevent the formation of biofilm on the wound area, thus enhancing the wound recovery progress [1]. Silver is a part of transition metals and has been classified as a precious metal due to its decreasing availability. Silver has interesting properties, yet the uses of the materials are limited due to silver instability towards oxygen [2]. Silver metal will oxidize spontaneously when exposed to free oxygen molecules. In these past few years, there has been an unprecedented rise in the application of nanoscience and nanotechnologies which lead to substantial progress in the production of nanomaterials. Thus, it had made possible to produce silver in nanoscale and these emerging nanoparticle products have attracted interest due to their physical, chemical, and biological properties in comparison with their macro-scaled counterparts [3]. These properties are being assessed through various analytical techniques.
Evaluation of silver nanoparticles (AgNPs) involves various types of analytical techniques which includes X-ray diffractometry (XRD) at wavelength (λ) = 1.54056 Å, X-ray photoelectron spectroscopy (XPS) usually between 300–400 eV, Fourier transform infrared spectroscopy (FTIR) in wavelength range of 400–4000 cm−1, ultraviolet visible spectroscopy (UV–vis spectroscopy) at the range of 400–500 nm, transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS) at scattering angle of 173°, and localized surface plasma resonance (LSPR) at wavelength of 300 nm to 1100 nm [4]. These analyses are important to assess the behavior, bio-distribution, and reactivity of these fabricated nanoparticles. Table 1 shows the basic functions of the analytical techniques used for the characterization of AgNPs. However, the result of these analytical techniques depends on the synthesis of AgNPs which also alter the physicochemical properties of the nanoparticles [5]. Recently, experiments with AgNPs have been conducted extensively due to their greater chemical, physical, and biological features compared to their bulk counterparts, such as their size, composition, crystallinity, shape, and structure.