a single molecule investigation of the photostability of quantum dots一个分子调查耐光性的量子点.pdfVIP

A Single Molecule Investigation of the Photostability of Quantum Dots 1. 2.¤ 1 Eva Arnspang Christensen , Pasad Kulatunga , B. Christoffer Lagerholm * 1 Department of Physics and Chemistry and MEMPHYS – Center for Biomembrane Physics, University of Southern Denmark, Odense M, Denmark, 2 Department of Physics, Hobart and William Smith Colleges, Geneva, New York, United States of America Abstract Quantum dots (QDs) are very attractive probes for multi-color fluorescence imaging in biological applications because of their immense brightness and reported extended photostability. We report here however that single QDs, suitable for biological applications, that are subject to continuous blue excitation from a conventional 100 W mercury arc lamp will undergo a continuous blue-switching of the emission wavelength eventually reaching a permanent dark, photobleached state. We further show that b-mercaptoethanol has a dual stabilizing effect on the fluorescence emission of QDs: 1) by increasing the frequency of time that a QD is in its fluorescent state, and 2) by decreasing the photobleaching rate. The observed QD color spectral switching is especially detrimental for multi-color single molecule applications, as we regularly observe spectral blue-shifts of 50 nm, or more even after only ten seconds of illumination. However, of significant importance for biological applications, we find that even small, biologically compatible, concentrations (25 mM) of b- mercaptoethanol has a significant stabilizing effect on the emission color of QDs, but that greater amounts are required to completely abolish the spectral blue shifting or to minimize the emiss