Surface-dependent quenching of Qdot emission can be a new tool for high resolution measurements

Single quantum dots (Qdots) are often used in the field of single-molecule imaging. Qdots are sensitive to changes in the physical interactions between the Qdots and the surrounding materials. However, the spectral changes in a single Qdot emission have not been studied in detail. Low-temperature plasma treatment of glass surfaces reduced the intensity of the 655 nm emission peak of Qdot655 on glass surfaces, but did not significantly change the intensity of the 580 nm emission. Silanization of the glass surface increases the thickness of the silane layer, and the 655 nm emission peak increased. When single Qdots on the untreated glass were imaged, plasma treatment decreased the intensity of red emission and increased yellow emission. When Qdots were brought close to the glass surface in the range of 28–0 nm, the red emission intensity decreased and the yellow emission intensity increased slightly. When single actin filaments were labeled with Qdots, fluctuations of the yellow and red emission of the Qdot were detected, which reflected the very small distance changes. Our results indicate that the local interaction of Qdots with the glass surface improves the spatial and temporal resolution of optical measurements of biomolecules labeled with Qdots.