A supramolecular hydrogel with identical cross-linking point density but distinctive rheological properties

Preparation of hydrogels with solely variable mechanical properties is greatly desired in the study of cell-matrix interactions in situ as well as cellular behaviors. Here, we fabricated a supramolecular polypeptide-DNA hydrogel, via the DNA self-assembly strategy, which possesses identical cross-linking point density but distinctive rheological properties. Keeping the cross-linking density constant, the rheological properties of the hydrogel can be adjusted by tailoring the stability of the DNA cross-linkers via easy programming of the DNA sequences. Through elongating and shortening the length of the DNA linker or inserting mismatch sites, the hydrogel can be strengthened, softened, or even fluidized, respectively. In addition, the mechanical properties can also be modulated by a pH-triggered conformation transition of the polypeptide backbone. Combining rapid physiological gelation and reversible thermal responsiveness, these supramolecular polypeptide-DNA hydrogels with solely tuned mechanical strength will promote studies on mechanical induced cell differentiation in situ, and have great potential in tissue engineering.