Self-assembly Of Gold Nanoclusters Research Articles

Ratiometric fluorescent detection of carbendazim in foods based on metallic nanoclusters self-assembled nanocomplex.

Indicator replacement assay combining with fluorescence resonance energy transfer (FRET) effect has attractive performance in sensing small molecules, however, there wasn't application in pesticide molecule sensing reported so far. In this work, we prepared a nanocomplex (NCP), AuAgNCs-CD, through self-assembly of gold nanoclusters (AuNCs), silver nanoclusters (AgNCs) and carboxymethyl-β-cyclodextrin (CM-β-CD) by one-step method. The emission of AuNCs was significantly enhance. It was found that FRET between the AuAgNCs-CD and rhodamine B (RhB) existed after AuAgNCs-CD combined with RhB. And carbendazim (CBZ) could induce anti-FRET effect through competing with RhB and binding to AuAgNCs-CD. Thus, this phenomenon was utilized to develop a ratiometric fluorescent detection of CBA. This method was applied in food sample detection and reliable results were obtained. Due to high sensitivity, rapidness and good selectivity, this ratiometric fluorescent method was expected to hold high application potential in monitoring CBZ in foods.

Self-Assembly of Gold Nanoclusters into a Metal-Organic Framework with Efficient Electrochemiluminescence and Their Application for Sensitive Detection of Rutin.

Ligand-protected gold nanoclusters (Au NCs) are promising electrochemiluminescence (ECL) emitters because of their striking optical properties and excellent biocompatibility, but free vibration and rotation of their ligand result in low ECL efficiency, dramatically limiting their applications. Herein, using the ligand of Au NCs as one of the building units, a Au NC-based metal-organic framework (Au NC-based MOF) was constructed by the coordination-assisted self-assembly strategy, which not only impedes the ligand rotation-induced energy dissipation but also diminishes the self-quenching effect due to the spatial distribution of Au NCs. As a proof of concept, the prepared GSH-Au NCs@ZIF-8 gives rise to a 10-fold enhanced anodic ECL efficiency compared to that of densely aggregated GSH-Au NCs with triethylamine as the coreactant. Based on high ECL efficiency of GSH-Au NCs@ZIF-8, a "signal off" sensing platform was proposed with rutin as a model analyte, achieving a low detection limit of 10 nM. Therefore, the strategy paves an effective and alternative methodology to enhance ECL efficiency of metal NCs, considerably broadening their potential applications in sensing analysis, clinical diagnosis, and light-emitting devices.

Preparation of fluorescent nanocomposites based on gold nanoclusters self-assembly

In this work, we report a facile strategy to fabricate fluorescent nanocomposites through the self-assembly of gold nanoclusters and polymers. The gold nanoclusters and polymers were modified with guest and host molecules, respectively. Then, the self-assembly based on the supramolecular interaction of gold nanoclusters and polymers can be conducted. Through optimizing the ratio between gold nanoclusters and polymers, we obtained novel fluorescent nanocomposites with high dispersity and uniform size in aqueous solution. Furthermore, the aggregated gold nanoclusters in the optimized nanocomposites exhibited an enhanced fluorescence. These superior properties of the fluorescent nanocomposites indicate their promising application in biological sensing and imaging.

Self-Assembly of Gold Nanoclusters on Molecularly Modified GaAs

The elaboration of closed-packed monolayers of Au55(PPh3)12Cl6 clusters on oxidized and non-oxidized GaAs surfaces is reported. The first part of this work describes the use of silanethiol modified GaAs oxide surfaces to trap 18 nm gold colloids and Au55(PPh3)12Cl6 clusters. The surfaces characterized by AFM measurements present high-quality coverage on a quite long range for both metallic species. The second part is devoted to the elaboration of Au55(PPh3)12Cl6 cluster monolayers on non-oxidized p-type GaAs substrates, functionalized with dithiol molecules. AFM measurements demonstrate the presence of closed-packed two-dimensional arrangements of Au55 clusters.

Self-assembly of gold nanoclusters on micro- and nanoelectronic substrates

Layer-by-layer self-assembly of hexanethiol stabilized gold nanoclusters by a series of alkanedithiol coupling agents [HS(CH2)nSH, n = 6, 8, 9, 12] onto SiO2/Si substrates with micron- and nanometre-scale Au electrodes is investigated by electron transport and XPS measurements. The self-assembly process for each layer consists of a two-step cycle of alkanedithiol treatment and gold cluster deposition. For maximized electron transport, critical features to optimize are the alkanedithiol chain length and the extent of dithiol coupling agent displacement of the hexanethiol ligand. Substitution of a phenethyl for the hexyl structure in the cluster ligand shell significantly enhances conductivity while substitution of a phenylene structure in the dithiol coupling agent has little effect on electron transport. Current–voltage characteristics for self-assembled depositions on the micron-scale electrode are found to be ohmic whereas I–V characteristics for analogous self-assemblies on the nanometre-scale electrode are initially nonlinear but become increasingly ohmic after about 3 cycles of deposition. The nonlinear features observed at the nanoscale are believed to be associated with Coulomb blockade.