α-Amino Acids as Reducing and Capping Agents in Gold Nanoparticles Synthesis Using the Turkevich Method

Abstract

Amino acid-capped gold nanoparticles (AuNPs) are a promising tool for various applications, including therapeutics and diagnostics. Most often, amino acids are used to cap AuNPs synthesized with other reducing agents. However, only a few studies have been dedicated to using α-amino acids as reducing and capping agents in AuNPs synthesis. Hence, there are still several gaps in understanding their role in reducing gold salts. Here, we used 20 proteinogenic α-amino acids and one non-proteinogenic α-amino acid in analogy to sodium citrate as reducing and capping agents in synthesizing AuNPs using the Turkevich method. Only four of the twenty-one investigated amino acids have not yielded gold nanoparticles. The shape, size distribution, stability, and optical properties of synthesized nanoparticles were characterized by scanning electron microscopy, differential centrifugal sedimentation, the phase analysis light scattering technique, and UV−vis spectroscopy. The physicochemical characteristics of synthesized AuNPs varied with the amino acid used for the reduction. We proposed that in the initial stage of gold salts reduction most of the used α-amino acids behave similarly to citrate in the Turkevich method. However, their different physicochemical properties resulting from differences in their chemical structures significantly influence the outcomes of reactions.

Conductive Gold Thin Film Prepared by the Two-Dimensional Assembly of Gold Nanoparticles on a Plastic Surface

“…It has been reported that certain amino acids are selectively adsorbed on the crystal faces of AuNPs. This might also affect the growth and connection of AuNPs on a substrate. ,− These factors account for the differences in the amino acids that are appropriate for the growth of AuNPs on a substrate and for the synthesis of AuNPs in bulk.…”

“…Intriguingly, the reducing agents suitable for the growth of AuNPs immobilized on the substrate differed from those used for synthesizing large AuNPs in bulk, as reported in previous studies. Figat et al reported the synthesis of AuNPs using all the α-amino acids except for Pro, Cys, Gln, and Arg . They found that when used as both reducing and stabilizing agents, Thr, Gly, Leu, and Ala produced larger AuNPs.…”

“…Gold nanoparticles (AuNPs) are nanomaterials that have been studied extensively. They are synthesized using a variety of approaches, some of which are energy-saving and employ “green chemicals” as reducing agents for chloroaurate ions and also as capping agents for the AuNPs. − In fact, we have also succeeded in synthesizing AuNPs using various amino acids . Several research groups have reported two-dimensional (2D) arrays of AuNPs formed by depositing AuNPs. ,− Many of the studies on the preparation of 2D arrays have featured inorganic substrates.…”

Marigold Like Structure from Methionine Mediated Growth of Positively Charged Gold Nanorod

“…The free À COOH and À NH 2 functional groups are known to participate in the reduction process. [22] TEM image after the growth reaction with peptide suggests a slight variation in the MGS (Figure 7B). The disk floret part in presence of peptide is comparable with the TEM obtained from Met mediated growth.…”

Probing the Adsorption Sites of 5‐amino‐2‐mercaptobenzimidazole Conformations on Colloidal Gold Nanoparticles Investigated by SERS and DFT

“…Among all nanomaterials, the gold nanoparticles (AuNPs) are proven to be safest and less toxic which make them superior for biomedical applications such as targeted drug delivery, diagnostics, plasmonic biosensing, tissue engineering and cancer therapy. [1][2][3][4][5][6] The unique size dependent optical properties of AuNP are well exploited in surface enhanced Raman scattering (SERS) which is strong tool to enhance the Raman signal of molecule adsorbed on a nanosurface. [7][8][9] The SERS enhancement mechanism originates both from electromagnetic effect and chemical charge transfer between adsorbing molecule and metal surface.…”