Methionine-Controlled Impediment of Secondary Nucleation Leading to Nonclassical Growth within Self-Assembled De Novo Gold Nanoparticles

Abstract

The conventional key steps for seed mediated growth of noble metal nanostructures involve classical and nonclassical nucleation. Furthermore, the surface of the seed catalytically enhances the secondary nucleation involving Au + to Au 0 reduction, thus providing in-plane growth of seed. In contrast to this well-established growth mechanism, herein we report the unique case of methionine (Met) controlled seed mediated growth reaction, which rather proceeds via impeding secondary nucleation in presence of citrate stabilized gold nanoparticle (AuNP). The interaction between the freshly generated Au + and thioether group of Met in the medium restricts the secondary nucleation process of further seed catalyzed Au + reduction to Au 0 . This incomplete conversion of Au + , as confirmed by X-ray photoelectron spectroscopy (XPS), results in a significant enhancement of the zeta (z) potential even at low Met concentration. Nucleation of in situ generated small-sized particles (nAuNPs) takes place on the parent seed surface followed by their segregation from the seed. Self-assembly process of these nAuNPs arises from the aurophilic interaction among the Au + . Furthermore, the time dependent growth of smaller particles to larger sized particles through assembly and merging within the same self-assembly validates the nonclassical growth. This strategy has been successfully extended towards the seed mediated growth reaction of AuNP in presence of three bio-inspired decameric peptides having varying number of 2 Met residues. The study confirms the nucleation strategy even in presence of single Met residue in the peptide and also the self-assembly of nucleated particles with increasing Met residues within the peptide.

Growth Reaction of Gold Nanorods in the Presence of Mutated Peptides and Amine‐Modified Single‐Stranded Nucleic Acids

“…This attachment helps in the assembly and merging process of the nanocrystal during the nanoparticle growth [16] . Recently we have also shown the similar assembly and merging process during the methionine controlled nonclassical growth in the seed mediated growth of gold NPs [17] …”

“…[16] Recently we have also shown the similar assembly and merging process during the methionine controlled nonclassical growth in the seed mediated growth of gold NPs. [17] The absorption nature during the growth reaction with 1 mM Arg group amino acids are similar to Ala group amino acids (Figure S13). Decreasing the concentration of Arg group amino acids from 1 mM to 10 μM, the rate of declining absorption intensity at 405 nm has also been lowered down (Figure 3A and S13).…”

Anisotropic Gold Nanomaterial Synthesis Using Peptide Facet Specificity and Timed Intervention

“…Additionally, methionine plays a role in chemical reduction of gold because it can be oxidized and form intermediate Au­(I)–methionine species . It has been proposed that Au­(I)–methionine complexation may decrease the rate of reduction and impede secondary nucleation on or near the particle surface . The former is evident in our previous work which explored the effect of substituting methionine with isoleucine in the Z2 sequence .…”

Origin of luminescence properties and synthetic methods for gold- and bimetallic gold-based nanomaterials

“…131 Recently, we also reported the role Au(I)/methionine metallic bonds. 132 Another interesting observation, which deals with the interaction towards the generation of emissive properties in nucleated Au(0)/ Au(I) NPs in aqueous medium, was reported. 132 The interaction of methionine with Au(I) led to the inhibition of secondary nucleation during the growth reaction of AuNPs.…”

“…132 Another interesting observation, which deals with the interaction towards the generation of emissive properties in nucleated Au(0)/ Au(I) NPs in aqueous medium, was reported. 132 The interaction of methionine with Au(I) led to the inhibition of secondary nucleation during the growth reaction of AuNPs. At a lower concentration of Au salt, this inhibition resulted in the generation of luminescent NPs (2.8 nm).…”