Study On Supramolecular Polypeptide-DNA Hydrogel

Hydrogel is an important mimetick of extracellular matrix that can provide physical environment and structural support for cells,thus it has been widely used for stem cell culture.Due to the rich responsiveness and dynamic controllability,supramolecular hydrogel has attracted more and more attentions in material sicene and tissue engineering.However,currently there is no one hydrogel sample which can sytisfy all the property requirements needed in tissue engineering like biocompatibility,biodegradability,permeability,mechanical strength,etc,and development of new supramolecular hydrogel material is critically desriable but still challenging in this field.Inspired by the structural characteristics of biological molecules,we successfully construct a new type of supramolecular hydrogel,named supramolecular polypeptide-DNA hydrogel,which can fulfill all the requirments above.Firstly,we prepared the supramolecular polypeptide-DNA hydrogel by using polypeptide as polymer backbone and DNA assembling structure(linear or branched)as crosslinker.The hydrogel can be formed at the normal cellular condition including physical salt concentration and pH via a two-conponent mixing method.Secondly,we systematically studied the mechanical property of the supramolecular polypeptide-DNA hydrogel.By changing the length of DNA “sticky ends” or inserting mismatch sites,or adjusting the secondary conformation of polypeptide backbone,we can realize the achievements of tuning the mechanical strenghth without changing the total crosslinking point density.Benefiting from the reversiable and danymic natural of DNA hybridization,the formed hydrogel possesses excellent shear-thinning property,injectable property and self-healing performance.Thirdly,based on the study on the hydrogel mechanical performance,we moved further to the real applicalions in biological medicine.The injectable property makes the hydrogel writable,which can be wroten into any shapes directly by syringe.By using branched DNA structure as crosslinker,the hydrogel can be modified by functional groups with desired ratio and postion,here fluorescent proteins as model guests.Combing with the 3D printing technich,the hydrogel is used for printing into any desired shapes and structures with living cells.pH responsive i-motif makes the hydrogel useful as a platform for enyzmes encapsulation and controlled release.Lastly,we expanded the supramolecualr DNA hydrogel system and constructed a supramolecular double network hydrogel by interpenetrating DNA and host-guest interaction.Different from the stepwise polymerization cross-linking,the supramolecular double network hydrogel can be prepared by one-pot assembling method under normal physiological conditions without any other harsh conditions.Meanwhile,the supramolecular double network hydrogel not only possesses enhanced mechanical property,but also shows specific and dynamic controllability,such as shear thinning and thixotropic behavior,a variety of biological enzymatic degradation.