Heteroatom-Doped Carbon Dots as Super-Resolution Imaging Probe via Tunable Fluorescence Blinking

Single-molecule localization microscopy (SMLM) is an advanced imaging technique that enables the visualization of nanoscale structures beyond the diffraction limit. However, optimizing fluorescence blinking parameters such as photon count, blinking cycle, switching cycle, and duty cycle are crucial for improving resolution. Here we show that heteroatom (N, S) doping in carbon dots (CDs) significantly changes the blinking behavior that alters the switching cycle between 1.4 to 8.5, localization precision between 13 and 26 nm, and average spatial resolution of 70 nm. We found that dopant atoms create additional trap-assisted pathways that increase the frequency of fluorescence “on”/“off” transitions under continuous excitation. While undoped CDs with a lower blinking cycle are ideal for quantitative SMLM imaging, N,S-doped CDs with a higher blinking cycle are suitable for high resolution SMLM imaging. This study demonstrates that heteroatom doping significantly alters the single-particle blinking properties of CD that widen their scope as a super-resolution bioimaging probe.