Preparation And Performance Of Tough And Repairable Tissue Adhesive Hydrogel Based On Nucleobase

Hydrogel materials have many excellent properties such as high water content,softness,rubber viscoelasticity and good biocompatibility,and widely used in food,cosmetics,medical and health,agriculture,environmental protection and other fields.Due to their resemblance to biological tissues,good biocompatibility and biological safety,polymer hydrogels have been extensively applicated in drug delivery carriers,wound dressings,contact lenses,tissue engineering,wearable devices and soft matter drivers.However,most traditional hydrogels showed poor mechanical properties,and limit their application.In the past two decades,various hydrogels with special network structure have been designed,which greatly improved the mechanical properties of hydrogels,typical structures include slip ring hydrogels,nanocomposite hydrogels,double network hydrogels and macromolecule microsphere hydrogels.With the development of tough hydrogels,simply improving the mechanical properties is far from meeting the practical requirements.In many cases,hydrogels are required to have certain adhesion and fatigue resistance,in order to bond with other materials and circulation machinery.Nucleobase is a heterocyclic compound with relatively stable properties,which can produce a variety of physical or chemical interactions with substrate surfaces,such as hydrogen bond,metal complexation,and hydrophobic interaction.Moreover,nucleobase molecules have molecular recognition and obtain adhesion via interacting with other components by hydrogen bonding,hydrophobic interaction,and π-π stacking.At the same time,the highly specific hydrogen bonds of nucleobases have great potential for preparation of supramolecular materials,which can be used as drugs delivery,molecular sensors and other functional structures.In Chapter 2,two different nucleobases,guanine(G)and cytosine(C)were introduced into poly(acrylamido-2-methylpropanesulfonic acid)(PAMPS)polymer backbone by sulfalation,then PAMPS-G/C hydrogel with good self-healing properties and excellent adhesion properties were successfully synthesized.The maximum tensile strength of hydrogel is 122 KPa,and the tensile strength after repairing can reach about 65% of the original strength.At the same time,it has good adhesion to plastics,PTFE sheets,glass,aluminum sheets and other substrates.It can easily adhere objects that are hundreds of times the quality of its own,and glass show the highest adhesion,reaching 5.05±0.15 KPa.In chapter 3,adenine(A)and thymine(T)were grafted onto PAMPS backbones,then a series of a PAMPS-A/T composite hydrogels with good self-healing properties and tissue adhesion was obtained.The introduction of adenine and thymine provides good adhesion to various substrates and tissues,and the hydrogen bond interaction between adenine and thymine can effectively improve the tensile strength and repairing ability of the hydrogel.The maximum tensile strength of the composite hydrogel was 144 KPa.After repairing,the tensile strength can reach 70% of the original strength.Moreover,the hydrogel showed good adhesion properties to plastics,PTFE,glass and aluminum,and the adhesion strength to glass can reach 5.30±0.09 KPa.In addition,the hydrogel also showed excellent adhesive behavior with various tissues such as heart,liver,spleen,lung and kidney of mice.