Polymeric DNA hydrogel: Design, synthesis and applications

Deoxyribonucleic acid (DNA) stores genetic information as a biomolecule, and also is regarded as a block copolymer and polyanion. Under favorable environments, DNA polymeric chains can spontaneously self-assemble into well-defined secondary or even higher ordered structures by following Watson-Crick base-paring rules, thus making DNA a competitive alternative in the fabrication of materials with precisely designed molecular structure and tailored functions. Among DNA based materials, DNA hydrogels comprising three-dimensional networks of DNA polymeric chains, have received considerable attention as a new class of polymeric materials particularly as biomaterials, showing great potential in a wide range of promising applications. Targeting to a specific application, DNA chain composed of four deoxyribonucleotide monomers (abbreviated as A, T, C and G) can be designed rationally and synthesized precisely, thus endowing a hydrogel with desirable functions and properties, such as responsiveness upon pH, enzyme, ions and biomolecules. Moreover, other functional materials may be introduced into DNA hydrogels, yielding multi-functional hybrid hydrogels. This review highlights recent progress on DNA hydrogels from a polymeric perspective, including general molecular design principles, synthesis strategies, and applications. DNA hydrogels are categorized according to the structure of building blocks including linear DNA, dendritic DNA and hybrid. The development roadmap of DNA hydrogels is sketched chronologically. Landmark work on the preparation of DNA hydrogels are presented to illustrate the design principles and synthesis strategy. The mechanical property and structure relationship is detailed to illuminate the mechanical regulation principle. Representative applications in biosensing, therapeutics, protein production, cell culture, intelligent device, and environmental protection are exemplified to show how DNA hydrogels are rationally and exquisitely designed to address application issues. The challenges and future development of DNA hydrogels are discussed at the end of the review.