Fluorescence was collected using the same objective and guided to a confocal pinhole to reject out-of-focus light. After passing through the pinhole, the fluorescence signal was split using a dichroic beam splitter into two beams and then filtered using learn more suitable band-pass filters before being detected by a pair of single-photon avalanche photon diodes. Time-tagged time-resolved (TTTR) measurements were performed during the experiments. TTTR SN-38 mouse is a time-correlated single-photon counting (TCSPC) technique capable of recording all time-related information for every detected photon, including the relative

time between the excitation pulse and photon emission as well as the absolute time between the start of the experiment and the photon emission. We used the TCSPC setup in TTTR mode to monitor the blinking behavior and lifespan of the QDs simultaneously. Results and discussion Figure 1 presents a schematic diagram depicting the process of attaching a single Au-NP to the end of an AFM probe. Initially, tapping mode image scanning was performed to determine the position of each Au-NP (Figure 1a). The AFM tip was then moved to a position above the selected Au-NP (Figure 1b). The probe was moved close to the Au-NP; the waveform generator was then used to apply a pulse of voltage to the AFM probe

(Figure 1c). In so doing, the Au-NP was evaporated and redeposited on the AFM tip (Figure 1d), whereupon the probe was withdrawn (Figure 1e). selleck chemical Tapping mode image scanning was performed once more to verify the absence of the Au-NP (Figure 1f). Figure 1 Schematic diagram depicting the procedures used to attach a single Au-NP to the AFM probe tip. (a) An image is taken to find the position of each Au-NP. (b) The AFM tip is moved

above the selected Au-NP. (c) The probe is moved toward the Au-NP and the waveform generator applies a pulse of voltage to the AFM probe. 3-mercaptopyruvate sulfurtransferase (d) The Au-NP is evaporated and redeposited on the AFM tip. (e) The probe is withdrawn. (f) An image is taken again to verify the absence of the Au-NP. The figures are not drawn to scale. AFM images of a 1.8-nm Au-NP before (first scan) and after (second scan) application of the voltage pulse are presented in Figure 2. The second AFM image confirms the transfer of the Au-NP following the application of a 2-V pulse for 32 ns. Figure 2 AFM images, cross sections, and 3D images of the Au-NP. AFM images of the 1.8-nm Au-NP on Si wafer (a) before and (b) after the application of a 2-V pulse for 32 ns. (c) Cross section following the line in (a). (d) Cross section following the line in (b). (e) 3D image of (a). (f) 3D image of (b). The red arrows indicate the position of the Au-NP before and after the application of 2-V pulse for 32 ns. In approximately half of the experiments, the AFM images do not reveal obvious differences following the application of the voltage pulse (see Additional file 1).