Photoswitchable Gold Nanoparticles for Super-Resolution Radial Fluctuation Imaging in Nanostructured Materials

Camera-based super-resolution approaches surpass the diffraction limit of conventional optical microscopy by relying on the stochastic activation and precise localization of fluorescent molecules. However, traditional probes such as organic dyes and quantum dots present challenges such as photobleaching and blinking variability, which limit their application in super-resolution imaging, particularly in non-liquid environments. Herein, the study demonstrates the potential of gold nanoparticles as a promising alternative for localization-based super-resolution imaging. The study specifically investigates how different surface functionalizations and states (aggregated vs isolated) of gold nanoparticles impact their photoluminescence properties, including fluorescence intensity, lifetime, and blinking behavior. By leveraging the intrinsic photoluminescence of gold nanoparticles, their capability is demonstrated as probes to achieve super-resolution imaging of nano-sized structures, at a resolution down to 100 nm, without the need for conventional imaging buffers. These proof-of-concept applications, which include imaging of silica nanosized wrinkles and logos, reveal that gold nanoparticles exhibit superior photophysical properties compared to common organic fluorophores, offering a promising alternative for super-resolution imaging. This work paves the way for the application of super-resolution fluorescence microscopy in materials science where non-liquid environments often restrict the use of traditional probes.