Super-Resolution Imaging in Non-Liquid Environments

Traditional microscopes have a limit to their resolution due to the physics of diffraction. Super-resolution techniques, based on stochastic activation and localization of fluorescent molecules, have allowed researchers to break this barrier but remain constrained by issues related to photobleaching and blinking instability in non-liquid environments. To address these issues, an international team of Swiss, German, UK and Chinese rsearchers led by Julie Probst and Stavros Stavrakis have developed a novel photoswitchable probe using gold nanoparticles (AuNPs). This probe enables super-resolution imaging down to 100 nm without the need for imaging buffer solutions, opening new opportunities in the nanoscale characterization of materials.

Key to this innovation is advanced surface functionalization of AuNPs and precise control of their aggregation state. For example, aggregated BPEI-coated AuNPs generated almost 104 photons per blinking event with a duty cycle as low as 10-3, outperforming conventional organic fluorophores. Notably, these nanoparticles enable stable imaging in ambient air due to their outstanding photostability. Additionally, mechanistic studies revealed that charge transfer between surface ligands and the metallic core enhances radiative processes, with plasmonic coupling in aggregated particles further boosing emission efficiency. Leveraging this understanding, the team employed super-resolution radial fluctuation (SRRF) algorithms to image nanoscale silicon wrinkles and focused ion beam-etched features, achieving a resolution of 105 nm.

Beyond immediate applications in nanofabrication quality control, the technology opens new frontiers for label-free analysis of air-exposed structures. Compared to electron or atomic force microscopy, AuNP-based imaging combines high resolution, operational simplicity, and environmental adaptability, promising transformative impacts in interfacial studies and nanodevice characterization.

Written by Junyue Chen

Read the published article here.