Covalent and non-covalent coupling of a Au₁₀₂ nanocluster with a fluorophore: energy transfer, quenching and intracellular pH sensing

Abstract

Interactions between an atomically precise gold nanocluster Au102(p-MBA)44 (p-MBA = para mercaptobenzoic acid) and a fluorescent organic dye molecule (KU, azadioxatriangulenium) are studied. In solution, the constituents form spontaneously a...

Engineering ligand chemistry on Au25 nanoclusters: from unique ligand addition to precisely controllable ligand exchange

“…Fig. 4c shows some fragment peaks from Au 25 Interestingly, the luminescence spectra show very similar shape and peak position (Fig. 5b, ESI, Fig.…”

Tailoring the interaction between a gold nanocluster and a fluorescent dye by cluster size: creating a toolbox of range-adjustable pH sensors

“…Therefore, the optical spectra of the larger nanoclusters were compared with the reported spectra for evaluation. Au 102 has a weak peak around 423 nm, 23 and Au 250 exhibits weak LSPR around 530 nm. 27 These isolated large-size nanoclusters were identified as Au 102 and Au 250 , respectively.…”

“…The steady-state fluorescent intensity of the KU dye at different pH was measured in the presence of three different-sized gold nanoclusters protected with the same type of ligand, to understand the size effect on the functionality of the fluorescent pH sensor. The fluorescence of the positively charged (+1) KU dye is quenched when they are bound to the negatively charged (–COO − ) p -MBA protected gold nanoclusters, leading to an energy transfer process from the KU dye to the gold nanocluster 23 ( Fig. 2a ).…”

“…The fluorescence of the positively charged (+1) KU dye is quenched when they are bound to the negatively charged (-COO -) p-MBA protected gold nanoclusters, leading to an energy transfer process from the KU dye to the gold nanocluster. 23 (Fig. 2a) This behaviour allows the fluorescence of the KU dye to quench and it is dependent on the surface charge of the nanocluster, which could be regulated by the amount of the nanoclusters or the number of charged ligands.…”

“…In our previous report, 23 we fabricated a fluorescent pH sensor by covalently binding a pH-independent dye (azaoxotriangulenium dye, KU) with an atomically precise and a water-soluble gold nanocluster (Au 102 ( p -MBA) 44 ; p -MBA = para -mercaptobenzoic acid) to create a functional hybrid material for intracellular pH imaging in live cells. The gold nanoclusters act as both nanocarriers and regulators of the fluorescence intensity in the targeted live cells.…”