A survey of place-exchange reaction for the preparation of water-soluble gold nanoparticles

Abstract

Water-soluble gold nanoparticles (AuNPs) have gained considerable attention because they offer a myriad of potential applications, especially in the fields of biology and medicine. One method to prepare such gold nanoparticles is through the well-known Murray place-exchange reaction. In this method, precursor gold nanoparticles, bearing labile ligands and with very good size distribution, are synthesized first, and then reacted with a large excess of the desired ligand. We report a comparison of the reactivity of several known precursor gold nanoparticles (citrate-stabilized, pentanethiol-stabilized, tetraoctylammonium bromide-stabilized, and 4-dimethylaminopyridine-stabilized) to several biologically relevant ligands, including amino acids, peptides, and carbohydrates. We found that citrate-stabilized and 4-dimethylaminopyridine-stabilized gold nanoparticles have broader reactivities than the other precursors studied. Citrate-stabilized gold nanoparticles are more versatile precursors because they can be prepared in a wide range of sizes and are very stable. The hydrophobic pentane-stabilized gold nanoparticles made them “inert” toward highly water-soluble ligands. Tetraoctylammonium bromide-stabilized gold nanoparticles exhibited selective reactivity, especially for small, unhindered and amphiphilic ligands. Depending on the desired ligand and size of AuNPs, a judicious selection of the available precursors can be made for use in place-exchange reactions. In preparing water-soluble AuNPs with biologically relevant ligands, the nature of the incoming ligand and the size of the AuNP should be taken into account in order to choose the most suitable place-exchange procedure.

Rational design of gold nanocarrier for the delivery of JAG-1 peptide

“…The obtained GNPs showed themselves as stable in aqueous media over several weeks and were characterized by means of UV-Vis, ATR-FT-IR, and DLS techniques. The surface plasmon resonance band (SPR) for the GNP solution, as determined by UV-Vis spectroscopy, was located at 522 nm, value in agreement with other literature data [24,[26][27][28]. The concentration of the GNP solution was calculated to be 11.5 nM based on the extinction coefficient at 522 nm [29,30].…”

A Versatile AuNP Synthetic Platform for Decoupled Control of Size and Surface Composition

“…30 An alternative is the synthesis of AuNPs with a more labile intermediate capping agent to facilitate the exchange. The use of AuNP protectants such as citrate, 31 phosphine, 32,33 4-(N,N-dimethylamino)pyridine (DMAP), 34,35 dioctylamine (DOA), 36 and tetraoctylammonium bromide (TOAB) 37 allows us to separate the synthesis of the AuNP core and the formation of a tailored ligand shell via a thiol-for-agent ligand-exchange procedure. 37 While each of the routes described above has been successfully implemented in certain protocols, their general applicability is limited by drawbacks such as (i) the available AuNP size range and size tunability, (ii) the uniformity in size and shape of the AuNP core, (iii) the stability and exchangeability of the intermediate capping agent, (iv) the yield and scalability of the reaction, and (v) the practicality of the procedure.…”

Effects of multivalent histamine supported on gold nanoparticles: activation of histamine receptors by derivatized histamine at subnanomolar concentrations

“…This layer can be easily replaced by ligands with a stronger binding affinity, such as for example thiols. 19,20 Thus, in a second step the ligand shell was substituted by a bivalent ligand. Bivalent ligands give access to further functionalization steps at the ligand periphery.…”