Silver and Gold Nanoparticles for Antimicrobial Purposes against Multi-Drug Resistance Bacteria

Abstract

Several pieces of research have been done on transition metal nanoparticles and their nanocomplexes as research on their physical and chemical properties and their relationship to biological features are of great importance. Among all their biological properties, the antibacterial and antimicrobial are especially important due to their high use for human needs. In this article, we will discuss the different synthesis and modification methods of silver (Ag) and gold (Au) nanoparticles and their physicochemical properties. We will also review some state-of-art studies and find the best relationship between the nanoparticles' physicochemical properties and potential antimicrobial activity. The possible antimicrobial mechanism of these types of nanoparticles will be discussed in-depth as well.

Keywords: antimicrobial resistance; gold nanoparticles; green chemistry; silver nanoparticles.

Figure 7

Schematic representation of the synthesis of dextran capped AuNPs (A). TEM image of localized MB@GNPDEX-ConA on K.Pneumoniae-12 bacterial surface and treatment. The schematic displays the cytological mass with accumulated conjugates (yellow arrow) and cell surface discomposure (B). The uniform morphology of bacterial aggregation and control cells according to concanavalin A (ConA)-mediated connection of conjugates (C). With light irradiation, the singlet oxygen produces ambient ¹ and cyto O_2, however, the cytosolic singlet oxygen influence the bactericidal effect and the absence of adherence through ambient oxygen. Singlet oxygen around the bacterial cells decreases the adherence ability (D) [135] Reprinted with permission from Elsevier. Table 2 displays other examples of the application of Au NPs in antimicrobial resistance activity (AMR).

Figure 1

Various synthesis methods of Ag and Au NPs.

Figure 2

Schematic illustration of synthesized VAuNPs by vanillin (the above illustration); FESEM image of P. aeruginosa in untreated, in presence of the (a) 50 μg/mL of VAuNPs, (b) Meropenem-200 μg/mL, (c) Meropenem (20 μg/mL) and (d) VAuNPs (50 μg/mL) (the below images) [24]. Reprinted with permission from Elsevier.

Figure 3

(A) Image of Esculentin-1a (1-21)-NH2 coated Au NPs and its interaction with bacteria. (B) Treatment of P. aeruginosa with (left) Au NPs@Esc(1-21) and (right) buffer as a control. (C) Schematic of P. aeruginosa cells treatment with Au NPs@Esc(1-21), Au NPs@PEG, and buffer [114]. Reprinted with permission from Elsevier.

Figure 4

Schematic illustration of the killing of bacterial cells by Au NPs (A); schematic of spectrum antimicrobial activity of Au NPs, naked drug, and drug-loaded Au NPs against oral pathogenic pathogens. (B) The AuNPs (100 µg) and drug-AuNPs show a wide-spectrum antimicrobial effect against the pathogens. AuNPs exhibited antimicrobial activity through the creation of a zone of inhibition ranging from about 17 mm against pathogens excluding B. subtilis, which shows less of a response with a 9 mm zone [117]. Reprinted with permission from Elsevier.

Figure 5

Schematic of an optical and sensing detection assay for the third generation of antibiotics through bacterial cells, (a) Optical detection assembly (b) The biosensing mechanism of antibiotics with bacterial cells [123]. Reprinted with permission from Elsevier.

Figure 6

Schematic illustration of the Silica-coated Au-Ag nanocages displays antibacterial activity through photothermal activity (A). Schematic of wound tissues with various treatments on three days (B). Photographs of bacterial colonies from tissues of various treatment groups (C) Reprinted with permission from [134]. Copyright 2022 American Chemical Society.