Synthesis of Gold Microstructures with Surface Nanoroughness Using a Deep Eutectic Solvent for Catalytic and Diagnostic Applications

Abstract

We synthesized highly monodisperse gold microparticles (AuMPs) using a deep eutectic solvent (DES) which composed of choline chloride and malonic acid as both a reaction medium and structure-directing agent. These microparticles exhibit distinctive surface nanoroughness and highly defined diameters that can be precisely controlled over a range of a few micrometers under different reductive conditions. The internal and external structures of the particles are thoroughly investigated by electron microscopy, which is further analyzed in association with their optical properties. We also investigate the gold microparticle concentration-dependent catalytic property employing a reductive reaction of 4-nitrophenol to 4-aminopenol as a model system. Importantly, the gold microparticles are densely functionalized with DNA and reversibly assemble with DNA-gold nanoparticle conjugate probes for the colorimetric detection of target DNA sequences, demonstrating that these novel structures can be utilized as platforms that quickly regulate the optical properties of plasmonic nanoparticles for diagnostic applications.

Potential applications of deep eutectic solvents in nanotechnology

“…ILs and DESs have been widely used as efficient dispersants during the synthesis reaction of nanoproducts. They have played roles in determining the shape, size and morphologies [47][48][49]. They are also capable of splitting small-scale structures into nano-scale and this aspect is added to their use as a functional dispersing solvent.…”

“…Oh et al [49] used a DES of ChCl and malonic acid as both a reaction medium and structure-directing agent to synthesize highly monodisperse gold microparticles. The product had a distinctive surface nanoroughness and highly defined diameters controlled precisely under different reductive conditions.…”

The role of deep eutectic solvents and carrageenan in synthesizing biocompatible anisotropic metal nanoparticles

“…The DES used served as solvent and catalyst for the condensation of furfuryl alcohol, followed by carbonization resulting in the formation of pores. Oh et al reported synthesizing highly monodispersed gold particles with a distinct rough surface and defined diameters using choline chloride and malonic acid [89].…”

On the Control and Effect of Water Content during the Electrodeposition of Ni Nanostructures from Deep Eutectic Solvents

“…46,48,49 To the best of our knowledge, only few studies have focused on the effect of water content on the electrochemical behaviour of DES 44,50,51 , as well as on the electrodeposition of nanomaterials. 52 On the one hand, water content has been proven essential to control the electrochemical properties of the DES. In fact, the presence of small amounts of water (up to 6 wt %), has shown to be beneficial for obtaining more uniform and compact Ni coatings.…”