AuNPs synthesis

Figure 4.4 Schematic representation of the two phase AuNPs synthesis proposed by Brust and coworkers in 1994.134...

One year later, Brust and Schiffrin [28,29] published a method for AuNPs synthesis which has a considerable impact on the overall field in less than a decade because it allowed the facile synthesis of thermally stable and air-stable AuNPs of reduced dispersity and controlled size for the first time. In this method, the gold colloids are sterically stabilized by organic molecules having thiol, amide or acid groups in contrast to the citrate reduction method where the gold colloids are kinetically stabilized in aqueous solutions by an electrical double layer [28,29], The main advantage of the Brust method is that the gold particles behave in a way as chemical compounds. These AuNPs can be repeatedly isolated and... 

In addition to chemical methods variety of physical methods has been employed for the synthesis of AuNPs. UV irradiation is used to improve the quality of the AuNPs when it is used in synergy with micelles or seeds [32,33], Near-IR laser irradiation provokes an enormous size growth of thiol-stabilized AuNPs [34], The presence of an ultrasonic field (200 kHz) allowed the control of the rate of AuC14" reduction in an aqueous solution containing only a small amount of 2-propanol and the sizes of the formed AuNPs are controlled by varying the parameters such as the temperature of the solution, the intensity of the ultrasound, and the positioning of the reactor [35,36], Sonochemistry was also used for the synthesis of AuNPs within the pores of silica and for the synthesis of Au/Pd bimetallic particles [37,38], Radiolysis has been used to control the size of AuNPs [39], Laser photolysis has been used to form AuNPs in block copolymer micelles. Laser ablation is another technique of AuNP synthesis that has been used under various conditions whereby size control can be induced by the laser [40,41],... 

Hybrid organic-gold nanoparticles may be obtained essentially in two ways, that is, by formation of an organic layer around preformed AuNPs or colloids, and by synthesis of AuNPs in the presence of organic ligands such as thiols, amines, or phosphines. 

Figure 4.6 Structure of oligothia-dendrimers used for the controlled formation of AuNPs,161 and of 1,2,3,4,5,6,7,8,9,10,11,12-dodecakis-p-tolylsulfanyl-coronene used for the synthesis of 1.0 nm AuNPs.162...

Figure 4.7 Structure of the amphiphilic fluorinated thiol used for the synthesis of water-soluble AuNPs.169...

Synthesis, properties, and applications of polymer-protected AuNPs have been reviewed by Shan and Tenhu and will not be covered in detail here.139 The basic motivation here is to better control the particle size and dispersity and to obtain robust materials avoiding metal loss during or after utilization of the polymeric material. 

Figure 4.9 Schematic representation of a solid-phase approach for the synthesis of monofunctional AuNPs.205...

Scheme 5 Synthesis of a AuNP-cored silylferrocenyl dendrimer (direct method)...

Later, Suri Iyer et al. synthesized similar Gb3-AuNPs but with different length of linkers and surface glycan densities [66], They conducted luciferase assay to measure the toxin-mediated inhibition of protein synthesis and found that Gb3-AuNPs were nontoxic to Vero monkey kidney cells and protected Vero cells from Shiga toxin in a dose-dependent manner. 

Scheme 11.20 General scheme for the synthesis of triferrocenyldendronized AuNPs (ligand substitution method).

Metal NPs represent an excellent biocompatibility with biomolecules and display unique structural, electronic, magnetic, optical, and catalytic properties, which in combination with their size have made them a very attractive material in biology (14-18). The attractive physicochemical properties of gold nanoparticles (AuNPs) are highly affected by its shape and size (19, 20). The size and properties of AuNPs are highly dependent on their preparation conditions (7, 21). Dos Santos et al. have reported the synthesis of AuNPs of different shapes and sizes (22). 

Currently, synthesis of novel AuNPs with unique properties and with applications in a wide variety of areas is the subject of substantial research (23, 24). 

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