Inducing reversible stiffness changes in DNA-crosslinked gels

Researchers have constructed a number of DNA-based nanodevices that undergo stepped configuration changes through the application of single-stranded DNA oligomers. Such devices can be incorporated into gel networks to create new classes of active materials with controllable bulk mechanical properties. This concept was demonstrated in a DNA-crosslinked gel, the stiffness of which was modulated through the application of DNA strands. Each crosslink incorporated a single-stranded region to which a DNA strand with a complementary base sequence (called the fuel strand) bound, thereby changing the nanostructure of the gel network. The gel was restored to its initial stiffness through the application of the complement of the fuel strand, which cleared the fuel strand from the crosslink via competitive binding. Stiffness changes in excess of a factor of three were observed. The ability to switch the mechanical properties of these gels without changing temperature, buffer composition, or other environmental conditions, apart from the application of DNA, makes these materials attractive candidates for biotechnology applications.