jp304494t_si_001.pdf (1.15 MB)
Redox Modification of CdSe–ZnS–Polymer Quantum Dots: Photoassisted Fluorescence Quenching and Recovery
journal contribution
posted on 2012-08-30, 00:00 authored by X. X. Yu, J. N. Li, K. C. Kwok, M. C. Paau, Martin M. F. Choi, K. K. Shiu, J. Y. Chen, N. H. CheungCommercial CdSe–ZnS–polymer quantum dots
(QDs) were
shown to be readily quenched by strong oxidants such as potassium
permanganate. When exposed to permanganate solution of millimolar
concentration for hours, damage was severe and the QDs would be permanently
bleached. When oxidant concentration was micromolar and reaction time
was minutes, oxidation would be mild and bleached QDs could recover
their fluorescence if the oxidant was removed and the QDs subsequently
irradiated. Light was essential in activating the fluorescence recovery.
Light could also transform mild oxidations into severe ones if administered
with the oxidant simultaneously. A model of the bleaching and recovery
was proposed. It was based on the oxidative attack of the Zn–ligand
bond and its repair. The model helped explain the critical role that
light played and was consistent with all the experimental observations.
By means of photocatalyzed oxidation of single QDs, a redox probe
of high spatial and temporal resolution was demonstrated.