Dr. Tsuyoshi Fukaminato, Assistant Professor in the Laboratory of Smart Molecules, Research Institute for Electronic Science, Hokkaido University, and his colleagues have successfully developed a novel fluorescent photoswitching molecule that can non-destructively read out information recorded on a single molecule.
In recent years, several fluorescent photoswitching molecules, which can be controlled the fluorescent property reversibly upon appropriate light irradiations, have been applied to “single-molecule optical memory” and “super-high resolution imaging”. Although such molecules are successfully used to demonstrate photoswitching of fluorescence even at the single-molecule level, the fluorescence quenching inherently induces the photoreaction of the switching unit and the recorded information is destroyed. Therefore, their performance is unsatisfactory because of the absence of “non-destructive fluorescence readout capability”.
To overcome such destructible readout problem, we employed the photoinduced electron transfer as the photoswitching mechanism. By connecting a fluorescent unit with complete separation of the spectral overlap to a switching unit, our research group developed a new fluorescent photoswitching molecule (shown below) based on intramolecular electron transfer. As a result, we were able to overcome the above issue. The fluorescence signal of individual molecules reversibly switched with one-step manner upon alternate irradiation with visible and UV light (figure below). In addition, it is worthwhile to note that both fluorescence “ON” and “OFF” states remain stable during the readout process upon excitation with 532 nm readout light (figure below). The result clearly indicates that non-destructive fluorescence readout can be achieved even at a single-molecule level, which means that fluorescent properties can be switched flexibly at any time. Thus, our research indicates that we have successfully developed a photoswitching molecule that truly functions at the molecular level.
This research was jointly conducted in collaboration with the research group led by Dr. Masahiro Irie, Professor, Department of Chemistry, Rikkyo University, and the research group led by Dr. Hiroshi Miyasaka, Professor, Graduate School of Engineering Science, Osaka University.
These research results were published in the US science journal ‘Journal of the American Chemical Society’ on April 6, 2011 (Eastern timezone in US).
