Redox-responsive and light-responsive DNA-based hydrogels and their applications

Abstract

The synthesis and applications of redox-responsive and photoresponsive hydrogels are introduced. One approach to synthesize redox-responsive hydrogels involves the crosslinking of polymers with nucleic acid duplexes and metal-carboxylate bridges. The second approach to assemble redox-responsive hydrogels includes the cooperative crosslinking of the polymers with duplex nucleic acids and donor-acceptor redox-active bridges. By reversible oxidation/reduction of the redox-active groups, switchable stiffness of the hydrogels is demonstrated. The use of redox-responsive hydrogels as shape-memory and self-healing materials is discussed. Photoresponsive hydrogels are introduced by the design of polymer matrices cooperatively stabilized by permanent crosslinking units, e.g. boronate ester/glucosamine, and trans/cis-photoisomerizable nucleic acid bridges. Alternatively, photoresponsive hydrogels crosslinked by nucleic acids and supramolecular complexes consisted of photoisomerizable host-guest or donor-acceptor complexes are introduced. Cyclic photoinduced formation/dissociation of the photoresponsive bridges lead to reversible stiffness of the hydrogels. In addition, Au nanoparticles (NPs) or nanorods (NRs) are immobilized in hydrogels. The light-induced thermoplasmonic melting of the nucleic acid bridges by Au NPs or NRs and switchable stiffness of the hydrogels are demonstrated. The stiffness-controlled hydrogels are applied as shape-memory and self-healing matrices and as controlled drug release materials. In addition, light-induced mechanical bending of bilayer hydrogels consisting of Au NPs/NRs is demonstrated.