A1 Journal article (refereed)
Covalent and non-covalent coupling of a Au102 nanocluster with a fluorophore : energy transfer, quenching and intracellular pH sensing (2021)

Hulkko, E., Lahtinen, T., Marjomäki, V., Pohjolainen, E., Saarnio, V., Sokolowska, K., Ajitha, A., Kuisma, M., Lehtovaara, L., Groenhof, G., Häkkinen, H., & Pettersson, M. (2021). Covalent and non-covalent coupling of a Au102 nanocluster with a fluorophore : energy transfer, quenching and intracellular pH sensing. Nanoscale Advances, 3(23), 6649-6658. https://doi.org/10.1039/D1NA00368B

JYU authors or editors

Publication details

All authors or editorsHulkko, Eero; Lahtinen, Tanja; Marjomäki, Varpu; Pohjolainen, Emmi; Saarnio, Ville; Sokolowska, Karolina; Ajitha, Ardra; Kuisma, Mikael; Lehtovaara, Lauri; Groenhof, Gerrit; et al.

Journal or seriesNanoscale Advances


Publication year2021


Issue number23

Pages range6649-6658

PublisherRoyal Society of Chemistry (RSC)

Publication countryUnited Kingdom

Publication languageEnglish


Publication open accessOpenly available

Publication channel open accessOpen Access channel

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/78513


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 weakly bound complex leading to quenching of fluorescence of the KU dye via energy transfer. The KU can be separated from the complex by lowering pH, leading to recovery of fluorescence, which forms a basis for an optical reversible pH sensor. However, the sensor is not a stable entity, which could be delivered inside cells. For this purpose, a covalently bound hybrid is synthesized by linking the KU dye to the ligand layer of the cluster via an ester bond. Covalent linking facilitates entry of the cluster–dye hybrids into cells via endocytosis. Inside cells, the hybrids accumulate in endosomes where Au102 releases its cargo via hydrolysis of the ester bond. Changes of the local pH inside endosomes regulate reversible fluorescence due to variations in the interactions between the Au102 cluster and the dye. This work presents a concept for delivering reporter molecules into cells by using atomically precise gold nanoclusters as carriers and paves the way for future developments of cluster-reporter sensors for in vivo measurements of e.g. absolute pH values or ion concentrations.

Keywordsnanoparticlescolouring agentschemical bondsfluorescencepHsensors

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Ministry reportingYes

Reporting Year2021

JUFO rating1

Last updated on 2024-22-04 at 18:59