The advent of super resolution optical microscopy (SRM) revolutionized imaging technologies providing new tools to visualize cells and synthetic materials with unprecedented detail. SRM maintains some of the key features of fluorescence microscopy, e.g. multicolour ability and minimal invasiveness, but overcome the diffraction limit (~ 250 nm) offering a nanometric resolution – namely Nanoscopy. Since then, it has become possible to directly detect and image subcellular features and synthetic nanostructures, impacting the fields of cell biology, chemistry and nanotechnology.
Although working principles and instrumentation of nanoscopes differ among techniques, they all share the same basic idea: the super resolution does not arise from physical means (e.g. optics) but from the accurate control of the state of the fluorescent markers – i.e. from the photochemistry and photophysics of the labels. The great technological advancements over the last years resulted in a plethora of nanoscopy techniques such as: stochastic optical reconstruction microscopy (STORM), photo-activated localization microscopy (PALM), and points accumulation for imaging in nanoscale topography (PAINT). All these techniques rely on bright photostable fluorophores that can switched on and off in a controlled manner. Therefore, the development of probes suitable for super resolution microscopy is currently the limiting factor for the performances of state-of-the-art nanoscopes.
As a result, further advancements in the field critically depend on the ability to develop and manipulate fluorescent probes, which are still numbered. This project aims to provide novel model systems for improved single molecule imaging by developing photoluminescent metal quantum clusters (MQCs) as advanced optical probes for super-resolution microscopy. MQCs are extremely promising probes for nanoscopy because they effectively combine ultra-small sizes, brightness and high photoluminescence (PL) efficiency with good photostability and chemical inertness, which render them interesting candidates as highly biocompatible fluorescent markers. To this purpose, property-designed nanochemistry routes by combining quantum size effects and surface engineered strategies will be used for producing multicolour MQCs. Using advanced microscopy techniques we aim at fully understanding of the photophysical and photochemistry features of different nanoparticle based probes, revealing properties like brightness, stabilility and photoswitching behaviour at single particle level. Finally, the toxicity and selective targeting of the new probes will be investigated. This research will have a strong impact on broad scientific community, namely materials science, colloidal chemistry and nanoscopy fields.
