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Photoswitchable NIR‐Emitting Gold Nanoparticles
Author(s) -
Bonacchi Sara,
Cantelli Andrea,
Battistelli Giulia,
Guidetti Gloria,
Calvaresi Matteo,
Manzi Jeannette,
Gabrielli Luca,
Ramadori Federico,
Gambarin Alessandro,
Mancin Fabrizio,
Montalti Marco
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201604290
Subject(s) - isomerization , chromophore , photochemistry , absorbance , luminescence , excitation , nanomaterials , colloidal gold , azobenzene , nanoparticle , chemistry , energy transfer , materials science , nanotechnology , optoelectronics , catalysis , chemical physics , organic chemistry , molecule , chromatography , electrical engineering , engineering
Photo‐switching of the NIR emission of gold nanoparticles (GNP) upon photo‐isomerization of azobenzene ligands, bound to the surface, is demonstrated. Photophysical results confirm the occurrence of an excitation energy transfer process from the ligands to the GNP that produces sensitized NIR emission. Because of this process, the excitation efficiency of the gold core, upon excitation of the ligands, is much higher for the trans form than for the cis one, and t → c photo‐isomerization causes a relevant decrease of the GNP NIR emission. As a consequence, photo‐isomerization can be monitored by ratiometric detection of the NIR emission upon dual excitation. The photo‐isomerization process was followed in real‐time through the simultaneous detection of absorbance and luminescence changes using a dedicated setup. Surprisingly, the photo‐isomerization rate of the ligands, bound to the GNP surface, was the same as measured for the chromophores in solution. This outcome demonstrated that excitation energy transfer to gold assists photo‐isomerization, rather than competing with it. These results pave the road to the development of new, NIR‐emitting, stimuli‐responsive nanomaterials for theranostics.