Fabrication of Stable and Luminescent Copper Nanocluster-Based AIE Particles and Their Application in β-Galactosidase Activity Assay

Abstract

Thiolated copper nanoclusters (CuNCs) with aggregation-induced emission characteristic are becoming a novel luminescent material, but it is still a challenging task to retain its bright luminescence in a neutral solution. In this work, we report a new copper nanocluster with aggregation-induced emission (AIE) enhancement property using a hydrophobic molecule as the protecting ligand, and brightly luminescent AIE particles of copper nanocluster were prepared via hydrophobic interaction. These CuNCs AIE particles possess uniform rod-like shapes, with sizes in hundreds of nanometer, and an intense luminescence; more importantly, its luminescence remains stable in neutral and alkaline solutions. It is found that 4-nitrophenol is able to effectively quench the luminescence of CuNC AIE particles through strong hydrophobic interaction and electron transfer between them. This strong quenching effect was adopted to develop a luminescent assay for β-galactosidase at physiological condition. This work presents a demonstration of preparing CuNC AIE particles with bright luminescence at neutral condition and gives an example of the use of AIE particles in monitoring the enzyme activity.

Stimuli‐Responsive Fluorescent Nanoswitches: Solvent‐Induced Emission Enhancement of Copper Nanoclusters

“…Feng et al. prepared brightly fluorescent AIE‐active particles of CuNCs with a protecting hydrophobic compound through hydrophobic interaction by adding poor solvents . Liu et al.…”

“…[8] Feng et al prepared brightly fluorescentA IE-activep articles of CuNCsw ith ap rotecting hydrophobic compound through hydrophobic interactionb ya dding poor solvents. [9] Liu et al utilized ap H-guided strategy for the fabricationo fC uNCs hybrid nanostructures with stable and bright luminescence. [10] For fluorescencee nhancement, the self-assembly of CuNCs can suppress the vibrationa nd rotationo fl igandso fC uNCs.…”

Luminescent Metal Nanoclusters for Potential Chemosensor Applications

“…Moreover, Li et al successfully exploited this method for the determination of glycoproteins in the egg white of chickens and human urine samples, which shows quantitative spike recoveries from 95% to 104%. Zhao and co-workers described 4-methylthiolphenol functionalized Cu NCs with a quantum yield of 2.4% in ethanol as an aggregation-induced emission probe and also consumed in β-galactosidase activity assay [150] by fluorescence "turn-off" response. Related to the nanoclusters of Au and Ag, Cu NCs with double-strand DNA (dsDNA) scaffold were also used in the recognition of microRNAs as defined next.…”

Tuning aggregation-induced emission nanoparticle properties under thin film formation

“…Within such a short period of time and in the absence of proper mixing under shear, AIE particles are likely to be distributed in a wide range of sizes, thereby affecting their ultimate brightness and applications. [12][13][14] It is believed that control of AIEgen particle size during formation influences their ultimate brightness, where packing of molecules minimizes intramolecular rotation. Despite numerous attempts, the size of AIEgen particles is still within the range of 200-300 nm.…”