Synthesis and Application of Silver Nanoparticles (Ag NPs) for the Prevention of Infection in Healthcare Workers

Abstract

Silver is easily available and is known to have microbicidal effect; moreover, it does not impose any adverse effects on the human body. The microbicidal effect is mainly due to silver ions, which have a wide antibacterial spectrum. Furthermore, the development of multidrug-resistant bacteria, as in the case of antibiotics, is less likely. Silver ions bind to halide ions, such as chloride, and precipitate; therefore, when used directly, their microbicidal activity is shortened. To overcome this issue, silver nanoparticles (Ag NPs) have been recently synthesized and frequently used as microbicidal agents that release silver ions from particle surface. Depending on the specific surface area of the nanoparticles, silver ions are released with high efficiency. In addition to their bactericidal activity, small Ag NPs (<10 nm in diameter) affect viruses although the microbicidal effect of silver mass is weak. Because of their characteristics, Ag NPs are useful countermeasures against infectious diseases, which constitute a major issue in the medical field. Thus, medical tools coated with Ag NPs are being developed. This review outlines the synthesis and utilization of Ag NPs in the medical field, focusing on environment-friendly synthesis and the suppression of infections in healthcare workers (HCWs).

Keywords: antiviral property; cytotoxicity; healthcare workers (HCWs); medical application; microbicidal property; silver nanoparticles (Ag NPs).

Figure 1

Various methods for silver nanoparticle (Ag NP) synthesis. Ag NPs have been synthesized using various methods that can be classified as solid, liquid, or gas-phase routes.

Figure 2

Environment-friendly method for Ag NP synthesis with the diameters control by glucose concentration. We have reported that environment-friendly processes were used to produce small Ag NPs (<10 nm) within a narrow size distribution. The diameters of generated Ag NPs were easily controlled by glucose concentrations [14].

Figure 3

The mechanism for microbicidal and antivirus activities of the Ag NP chitin nanofiber sheet (CNFS). To prevent contact infection of healthcare workers (HCWs), an Ag NP chitin nanofiber sheet (CNFS) was developed, showing strong microbicidal activity against microorganisms/viruses via reactive oxygen species (ROS) and silver ions on the surface of substratum.

Figure 4

The microbicidal/antiviral activity of materials using Ag NPs/CNFS with various concentration of Ag NPs [48]. The activities of various concentrations of Ag NPs on CNFS against E. coli (a) and H1N1 Influenza A (b). Data are mean value ± standard deviation (n = 6); the asterisk indicates a statistically significant difference (p < 0.01) using two-sample t-test vs. control. ND means non-detection. The vertical axis is listed with a common logarithm. For example, with an Ag NP concentration of 8.5 μg/cm² in the CNFS in (b), there was a reduction of greater than 2 log10 (100-fold) corresponding to a reduction of viral titers by approximately 99%.

Figure 5

The application of the Ag NP/CNFS complex to protect HCWs. To prevent contact infection of HCWs, we have proposed medical consumables, such as infection-protective coats, masks, and gloves, immobilized Ag NPs.