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Dimerization of Organic Dyes on Luminescent Gold Nanoparticles for Ratiometric pH Sensing
Author(s) -
Sun Shasha,
Ning Xuhui,
Zhang Greg,
Wang YenChung,
Peng Chuanqi,
Zheng Jie
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201509515
Subject(s) - chemistry , protonation , luminescence , fluorescence , rhodamine , colloidal gold , photochemistry , nanoparticle , rhodamine b , nanotechnology , combinatorial chemistry , organic chemistry , materials science , photocatalysis , ion , catalysis , physics , optoelectronics , quantum mechanics
Synergistic effects arising from the conjugation of organic dyes onto non‐luminescent metal nanoparticles (NPs) have greatly broadened their applications in both imaging and sensing. Herein, we report that conjugation of a well‐known pH‐insensitive dye, tetramethyl‐rhodamine (TAMRA), to pH‐insensitive luminescent gold nanoparticles (AuNPs) can lead to an ultrasmall nanoindicator that can fluorescently report local pH in a ratiometric way. Such synergy originated from the dimerization of TAMRA on AuNPs, of which geometry was very sensitive to surface charges of the AuNPs and can be reversely modulated through protonation of surrounding glutathione ligands. Not limited to pH‐insensitive dyes, this pH‐dependent dimerization can also enhance the pH sensitivity of fluorescein, a well‐known pH‐sensitive dye, within a larger pH range, opening up a new pathway to design ultrasmall fluorescent ratiometric nanoindicators with tunable wavelengths and pH response ranges.