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DNA materials micro-structuration and strain sensing

Rémi Merindol Centre de Recherche Paul Pascal, Bordeaux, France

Inspired by biological soft-tissues, the fabrication of addressable, biocompatible and hierarchically structured materials is a key challenge for material science. DNA provides synthetics materials with the highest level of molecular structural control and nanoscale complexity (DNA origami…). Yet processes to create micro and macro-structured DNA architectures are scarce.

First I will present a new method at the interface of biochemistry and macromolecular physics to prepare various all-DNA microstructures. Fast pathway controlled micro-structuration rely on two antagonistic processes : a new sequence dependent LCST-type phase-transition that promotes self-assembly at high temperature ; and DNA hybridization which prevails at low temperature. We developed multiple strategies to navigate such complex landscapes and form addressable homogeneous (A) or core-shell (B) particles and to self-assemble them into multiparticle superstructures (C) and light responsive hybrid DNA/gold-nanoparticles (D).

Then I will move to the design of programmable soft mechanofluorescent DNA hydrogels. I will show how to prepare thermoplastic DNA hydrogels which sustain more than 300% strain before failing. We functionalized these hydrogels with force-sensing mechanofluorescent modules which consist in a weak DNA duplex functionalized on one side with a fluorophore and one the other side with a quencher. At rest Förster Resonance Energy Transfer (FRET) prevents fluorescence ; whereas stretching opens the duplex which results in FRET decreases and fluoresce increase (E). We explored the influence of different modules on strain-sensing and on fluorescence recovery after strain release. I will finally show few examples of inhomogeneous strain visualization in composite materials (F) and frozen hydrogels (G).

Figure : Pathway controlled formation various DNA microstructures : (A) homogeneous and (B) core-shell particles, (C) continuous cellular hydrogel and (D) light-responsive hybrid DNA/gold-nanoparticles. The red fluorescence of mechanofluorescent DNA hydrogels increases with strain (E) which allows fracture visualization in cellulose-DNA composite (F) and microscale freezing patterns (G).

R. Merindol, A. Walther, Materials Learning from Life : Concepts for Active, Adaptive and Autonomous Molecular Systems. Chem. Soc. Rev. (2017).
R. Merindol, S. Loescher, A. Samanta, A. Walther. Pathway-controlled formation of mesostructured all-DNA colloids and superstructures. Nat. Nanotechnol. (2018).
R. Merindol, G. Delechiave, L.H. Catalani, A. Walther, Modular Design of Programmable Mechanofluorescent DNA Hydrogels. Nat. Commun. (Review process).