Progress in Laser Ablation and Biological Synthesis Processes: "Top-Down" and "Bottom-Up" Approaches for the Green Synthesis of Au/Ag Nanoparticles

Abstract

Because of their small size and large specific surface area, nanoparticles (NPs) have special properties that are different from bulk materials. In particular, Au/Ag NPs have been intensively studied for a long time, especially for biomedical applications. Thereafter, they played a significant role in the fields of biology, medical testing, optical imaging, energy and catalysis, MRI contrast agents, tumor diagnosis and treatment, environmental protection, and so on. When synthesizing Au/Ag NPs, the laser ablation and biosynthesis methods are very promising green processes. Therefore, this review focuses on the progress in the laser ablation and biological synthesis processes for Au/Ag NP generation, especially in their fabrication fundamentals and potential applications. First, the fundamentals of the laser ablation method are critically reviewed, including the laser ablation mechanism for Au/Ag NPs and the controlling of their size and shape during fabrication using laser ablation. Second, the fundamentals of the biological method are comprehensively discussed, involving the synthesis principle and the process of controlling the size and shape and preparing Au/Ag NPs using biological methods. Third, the applications in biology, tumor diagnosis and treatment, and other fields are reviewed to demonstrate the potential value of Au/Ag NPs. Finally, a discussion surrounding three aspects (similarity, individuality, and complementarity) of the two green synthesis processes is presented, and the necessary outlook, including the current limitations and challenges, is suggested, which provides a reference for the low-cost and sustainable production of Au/Ag NPs in the future.

Keywords: Au/Ag nanoparticles; green synthesis; laser ablation; molecular structure; potential application.

Figure 1

Properties and application of Au/Ag NPs in different fields.

Figure 2

Two different methods to fabricate Au/Ag NPs: top-down and bottom-up.

Figure 3

Mechanism of nanoparticle synthesis during the LAL process: (A) interaction of colloidal particles with laser beam; (B) polymerization and reaction of generated NPs with colloidal particles; (C1) generates an expansive cavitation bubble, within which crystallized NP is formed through nucleation and coalescence; (C2) incident laser pulse is adsorbed by the bulk material to form plasma. Reprinted/adapted with permission from Ref. [32]. Copyright 2014, Royal Society of Chemistry.

Figure 4

Evolution of laser-induced plasmas in liquids; (a,b) high-temperature chemical reaction between the target ablation; (c) the laser-induced plasma and the liquid; (d) chemical reaction inside the liquid. Reprinted/adapted with permission from Ref. [33]. Copyright 2007, Elsevier.

Figure 5

Time duration of plasma emission, shock wave formation, and bubble collapse during the LAL process. Reprinted/adapted with permission from Ref. [36]. Copyright 2015, Elsevier.

Figure 6

Plasma emission images after laser irradiation for 600 ns (pulse durations were 30 ns, 50 ns, and 100 ns, respectively). Reprinted/adapted with permission from Ref. [39]. Copyright 2015, AIP Publishing.

Figure 7

TEM images and the particle size distributions of silver nanoparticles prepared by laser ablation using a silver plate in PVP solutions at various concentrations. Reprinted/adapted with permission from Ref. [31]. Copyright 2008, Elsevier.

Figure 8

Schematic diagram of the formation of phyllanthin stabilized Au/Ag NPs.

Figure 9

Mechanism of intracellular and extracellular microbes mediated synthesis of NP. Reprinted/adapted with permission from Ref. [55]. Copyright 2016, Elsevier.

Figure 10

(a) General mechanism of the algae-mediated biosynthesis of metal nanoparticles Reprinted/adapted with permission from Ref. [55]. Copyright 2016, Elsevier. (b) Schematic diagram of the intracellular and extracellular synthesis mechanisms of algae-mediated nanoparticles. Reprinted/adapted with permission from Ref. [68]. Copyright 2020, Elsevier.

Figure 11

TEM micrographs of Au NPs produced by F. vesiculosus in pH 4 (a) and pH 7 (b) solutions. Reprinted/adapted with permission from Ref. [70]. Copyright 2009, Elsevier.

Figure 12

Effects of reaction time, temperature, pH, and extract concentration on the biosynthesis of Au NPs. Reprinted/adapted with permission from Ref. [74]. Copyright 2017, Elsevier.

Figure 13

Schematic illustration of the fabrication process of pAu NPs and pPt NPs using LATW and dealloying for biosensing applications. Reprinted/adapted with permission from Ref. [79]. Copyright 2022, Elsevier.

Figure 14

Leaf extract and synthesized nanoparticles of medicinal plant poliomyelitis and their anticancer activity. Reprinted/adapted with permission from Ref. [85]. Copyright 2020, Elsevier.