Lipid Expansion Microscopy

Strategies to visualize cellular membranes with light microscopy are restricted by the diffraction limit of light, which far exceeds the dimensions of lipid bilayers. Here, we describe a method for super-resolution imaging of metabolically labeled phospholipids within cellular membranes. Guided by the principles of expansion microscopy, we develop an approach featuring cell-permeable reagents that enables direct chemical anchoring of bioorthogonally labeled phospholipids into a hydrogel network and is capable of tunable, isotropic expansion, thus facilitating super-resolution imaging of cellular membranes. We apply this method, termed lipid expansion microscopy, to visualize organelle membranes with precision, including a unique class of membrane-bound structures known as nuclear invaginations. As it is compatible with standard confocal microscopes, lipid expansion microscopy will be widely applicable for super-resolution imaging of phospholipids and cellular membranes in numerous physiological contexts.