Fig. 1

Preparation and operational principle of modular mechanofluorescent DNA hydrogels. a Enzymatic synthesis of the ssDNA hydrogel precursors and assembly of the DNA hydrogel via X/X* duplex crosslinks. b Self-assembly of a typical mechanofluorescent force-sensing module. The red-emitting fluorophore and the quencher are brought in close proximity and FRET prevents the emission of red fluorescence. c The pristine DNA hydrogel is functionalized with a force-sensing module and with a green-emitting reference fluorophore to form the mechanofluorescent hydrogel. At rest, the hydrogel fluoresces in green as only the reference fluorophore emits light due to an efficient FRET-based quenching in the force-sensing module. Stretching of the hydrogel breaks the sacrificial duplex of the mechanosensing module (in pink), which separates the red-emitting fluorophore from the quencher and decreases FRET. The red-emitting fluorophore starts emitting and the red fluorescence increases compared to the unaffected green fluorescence of the reference. FRET, forster resonance energy transfer