Correlative super-resolution bright-field and fluorescence imaging by microsphere assisted microscopy

The resolution of fluorescence imaging has been significantly enhanced with the development of super-resolution imaging techniques, surpassing the diffraction limit and reaching sub-diffraction scales of tens of nanometers. However, the resolution of the bright-field images of cells is restricted by the diffraction limit, leading to a significant gap between the resolutions of fluorescence and bright-field imaging, which hinders the research of the precise distribution of intracellular nanostructures. A microsphere superlens offers a promising solution by providing label-free super-resolution imaging capabilities compatible with fluorescence super-resolution imaging. In this study, we used microsphere superlenses to simultaneously enhance the resolution of bright-field and fluorescence imaging, achieving correlated super-resolution bright-field and fluorescence imaging. Compared to conventional bright-field images, we improved the imaging resolution from λ/1.3 to λ/4.2. A correlative super-resolution of mouse skeletal muscle cells was achieved, enabling the clear observation of the precise distribution of nanoparticles in mouse skeletal muscle cells. Furthermore, microsphere superlenses inherit the advantages of optical imaging, which is expected to enable the capturing of ultrafast biological activity within living cells with extremely high temporal resolutions.