Here we created a dynamic gel system that allows programming of a metastable assembly state which eventually drives the system to a new material exhibiting a gel-to-gel transition.

Self-assembly of fluorenylmethoxycarbonyl-protected diphenylalanine (FmocFF)i nw ater is widely known to produce hydrogels. Typically,c onfocal microscopy is used to visualize such hydrogels under wet conditions, that is, withoutf reezing or drying. However,k ey aspects of hydrogels like fiber diameter,n etwork morphologya nd mesh size are sub-diffraction limited features and cannot be visualized effectively using this approach. In this work, we show that it is possible to image FmocFF hydrogels by Points Accumulationfor Imaging in Nanoscale Topography (PAINT) in native conditions and without direct gel labelling. We demonstrate that the fiber network can be visualized with improved resolution (% 50 nm) both in 2D and 3D.Q uantitativei nformation is extracteds ucha sm esh size andf iber diameter.T hismethodcan complement theexistingc haracterizationt ools forh ydrogels andp rovideu seful information supporting the design of new materials.