Multicolor expansion fluorescence emission difference microscopy to reveal potential organelle contacts

Biologists have long been interested in the submicroscopic structures of cells and interactions between organelles. However, due to resolution limitations, investigating cell biology using fluorescence microscopy remains a challenge. In recent decades, super-resolution microscopy has been developed as an essential solution. Recently, a new microscopic technique called expansion microscopy has been developed, which circumvents this resolution limit by increasing the size of the biological sample, thus allowing for super-resolution of the enlarged structure. In this study, we combined expansion microscopy with fluorescence emission difference microscopy (ExFED) and achieved a spatial resolution of approximately 40 nm in mammalian cells. Delicate subcellular and sub-organelle structures were investigated, and potential contacts were detected. The results indicated that ExFED is a simple and powerful super-resolution method for studying biological specimens.