Natural Glycyrrhizic Acid-Tailored Responsive Supramolecular Gels

Supramolecular gel generally refers to the molecules through noncovalent interactions of three-dimensional(3D)reticular spatial structures self-assembled in the solvents,which can wrap and tie a large number of solvent with potential applications in many fields of sensors,drug delivery,tissue engineering etc.As an ideal building block,glycyrrhizic acid,a natural three terpenoid saponin,is a typical amphiphilic natural product.Its sweetness is 50 times that of sucrose,and is widely used as a sweetener.What's more,glycyrrhizic acid has many biological activities including antiinflammatory,detoxification and liver preservation,and has been widely used in many fields like food,medicine,cosmetics and so on.To date,it has beebn reported that glycyrrhizic acid can not only assemble into supramolecular hydrogels,but also be used as the stabilizer for the oil-in-water emulsions.However,it is still rate to modify glycyrrhizin acid with resposive moieties,thus forming functional supramolecular gels.As our continuous work on self-assembly of amphiphilic molecules,in this thesis natural glycyrrhizic acid was utilized as the molecular skeleton of gelators.Their gelation ability,microstructures,assembled mechanism,mechanical properties and biological applications were studied in detail.This work may expand and enrich the glycyrrhizic acid-based supramolecular gel systems.The main text was as following:1)We synthesized a photo-responsive molecule trans-GAG,where glycyrrhizic acid as was linked with azobenzene ends by the amide groups.The results showed that trans-GAG could form supramolecular gels in a number of solvents.Moreover,their morphologies and mechanical properties were studied in detail before and after the ultraviolet light.In addition,the injectable and self healing properties of these supramolecular gels layed a foundation for its potential applications in 3D printing and surface coatings.2)We synthesized a gelator TGA with AIE effect,where glycyrrhizic acid and tetraphenylethylene(TPE)were used as the gelator backone and the AIEgen,respectively.The results showed that TGA has good gelling properties,and has good biocompatibility and bioactivity.In this part,we explored the gelation properties of and self-assembly morphology TGA,further explored properties of AIE of TGA.