A Biocompatible Supramolecular Hydrogel Mesh for Sample Stabilization in Light Microscopy and Nanoscopy

Most embedding media for live and fixed samples were not designed for microscopy and have issues including long polymerization times, peak of toxicity toward the sample during the sol-gel transition, and irreversibility of this transition. Gels derived from biological sources are widely used in microscopy, but their precise composition is ill-defined and can vary between batches. Non-physiological temperatures and/or specific enzymatic solutions are often needed to revert the gel back to the sol state to allow sample recovery. Recovering the sample undamaged is important for multiple purposes, from the ability to release a living organism back into its environment and re-observe it at a later stage, to interrogating the sample once freed from the gel after imaging. We describe a supramolecular hydrogel that enables the observation of small living organisms using light microscopy, with simple sample recovery through vigorous pipetting with water. The organisms can be recovered alive and capable of further development into adulthood, which represents a significant advancement, as most other matrices require release conditions such as heating, the addition of chemicals, or mechanical disruption, which can damage or kill the embedded organisms. Furthermore, the gel is compatible with super-resolution multi-colour STED nanoscopy.