One-Component DNA Mechanoprobes for Facile Mechanosensing in Photopolymerized Hydrogels and Elastomers

Abstract

DNA mechanosensors offer unique properties for mechano-adaptive and self-reporting materials, such as programmable bond strength and geometrical strain response, tunable fluorescent strain sensing, interfacing to biological systems, and the ability to store mechanical information. However, the facile incorporation of advanced DNA motifs into polymer networks and achieving robustness in application settings remain difficult. Herein, we introduce one-component DNA mechanoprobes that can be easily polymerized into polymer hydrogels and even elastomers to allow strain-induced fluorescence sensing. The all-in-one mechanoprobe contains a DNA hairpin for programmable force sensing, an internal fluorophore–quencher pair as a reporter, and methacrylamide groups on both ends for rapid and facile photopolymerization into networks based on the nontoxic water-soluble monomer methoxy triethylene glycol acrylate (mTEGA). In addition to mechanosensing hydrogels, we utilize the low T g of p­(mTEGA) to develop the first bulk elastomer materials with DNA force sensors, which show high elasticity and stronger mechanofluorescence. The system makes decisive steps forward for DNA-based mechanoprobes by overcoming the classical multicomponent design of such probes, allowing photopolymerization useful for the design of complex objects or even 3D printing and demonstrating that such motifs may even be useful in dry bulk materials.

Tailoring the Properties of Optical Force Probes for Polymer Mechanochemistry

“… [46] While these OFPs enable the detection of forces in the pN range, which is suitable for soft biomimetic hydrogels, their incorporation into artificial materials is synthetically challenging, which Walther and coworkers recently have tackled with acrylamide‐terminated DNA OFP crosslinkers. [47] Since the analysis of mechanical processes in biohybrid materials and the associated interaction between living systems and polymers is an emerging challenge, [48] nucleic acid and genetically engineered protein [49] OFPs could become increasingly important.…”

DNA‐Engineered Hydrogels with Light‐Adaptive Plasmonic Responses

“…[ 41–45 ] However, the use of DNA‐engineered optical elements for generating bulk color responses is still at infancy, and involves mostly the use of fluorophores. [ 46,47 ] DNA‐engineered ANP responses have been demonstrated in solution but not widely explored in bulk macroscopic materials. [ 48,49 ]…”

Supramolecular Rings as Building Blocks for Stimuli-Responsive Materials

“…Indeed, temperature changes, light irradiation, mechanical force, or the changing polarity of the environment can serve as stimuli that lead to the assembly or disassembly of the chromophores, which can in turn trigger a defined optical response in the material. Chromophore systems that have been used in this context include excimer-forming dyes [ 7 , 8 ], energy-transfer pairs [ 9 ], charge-transfer complexes [ 10 ], and photo-induced electron transfer dye pairs [ 11 ]. The corresponding polymers featuring these dye systems have been used to sense, e.g., temperature [ 12 ], chemicals [ 13 , 14 ], and mechanical deformation [ 8 , 9 , 11 , 15 , 16 , 17 , 18 ].…”

“…Chromophore systems that have been used in this context include excimer-forming dyes [ 7 , 8 ], energy-transfer pairs [ 9 ], charge-transfer complexes [ 10 ], and photo-induced electron transfer dye pairs [ 11 ]. The corresponding polymers featuring these dye systems have been used to sense, e.g., temperature [ 12 ], chemicals [ 13 , 14 ], and mechanical deformation [ 8 , 9 , 11 , 15 , 16 , 17 , 18 ]. Whereas simple blending of polymers with a suitable dye is often sufficient to create responsive materials [ 2 , 3 , 4 , 7 ], it can be beneficial to covalently incorporate the chromophores into a polymer matrix.…”

“…Accordingly, we set out to explore new types of linear molecules in which dye pairs are covalently connected by a short linker ( Figure 1 ). The intramolecular association of the chromophores, which can be influenced via the interaction strength of the two motifs [ 7 , 21 ] as well as by auxiliary groups that provide directional non-covalent interactions [ 9 , 18 ], might lead to the formation of dynamic cyclic structures with quenched or altered fluorescence emission. Such motifs could display straightforward stimulus-induced assembly or disassembly, and appear to be attractive candidates for the development of a wide range of novel stimuli-responsive sensor motifs, notably, mechanochromic mechanophores [ 8 , 9 , 10 , 18 , 25 , 26 , 27 ].…”