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pH-Responsive Near-Infrared Emitting Gold Nanoclusters |
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| Authors: | Dr Shaochen Zhou Lotta Gustavsson Dr Grégory Beaune Dr Sourov Chandra Prof Jukka Niskanen Prof Janne Ruokolainen Dr Jaakko V I Timonen Prof Olli Ikkala Dr Bo Peng Prof Robin H A Ras |
| Institution: | 1. Department of Applied Physics, School of Science, Aalto University, 00076 Espoo, Finland;2. Department of Applied Physics, School of Science, Aalto University, 00076 Espoo, Finland
Center of Excellence in Life-Inspired Hybrid Materials LIBER, Aalto University, 00076 Espoo, Finland;3. Department of Chemical Engineering and Metallurgy, School of Chemical Engineering, Aalto University, 00076 Espoo, Finland |
| Abstract: | Near-infrared (NIR) fluorophores with pH-responsive properties suggest merits in biological analyses. This work establishes a general and effective method to obtain pH-responsive NIR emissive gold nanoclusters by introducing aliphatic tertiary amine (TA) groups into the ligands. Computational study suggests that the pH-responsive NIR emission is associated with electronic structure change upon protonation and deprotonation of TA groups. Photo-induced electron transfer between deprotonated TA groups and the surface Au-S motifs of gold nanoclusters can disrupt the radiative transitions and thereby decrease the photoluminescence intensity in basic environments (pH=7–11). By contrast, protonated TA groups curb the electron transfer and restore the photoluminescence intensity in acidic environments (pH=4–7). The pH-responsive NIR-emitting gold nanoclusters serve as a specific and sensitive probe for the lysosomes in the cells, offering non-invasive emissions without interferences from intracellular autofluorescence. |
| Keywords: | Gold Nanoclusters Near-Infrared Photoluminescence Tertiary Amine pH-Responsive |