| Hydrogel is a new polymer with high water content and high biocompatibility.It has a wide range of applications in tissue engineering,drug delivery and wound repair.However,the traditional hydrogel has poor mechanical properties,low tissue adhesion,weak environmental adaptability and single function,which seriously limit its wide application in the field of biomedicine.Therefore,it is of great significance to develop a new type of hydrogel with high strength,high viscosity and high environmental adaptability.Objective:To construct a new nanocomposite crosslinker with the self-assembly of natural biological macromolecule casein and metal silver-sulfur coordination.To construct the high performance nanocomposite hydrogel with acrylamide as polymer monomer,and explore its application prospect in biomedical fields.Methods:(1)Based on the structural characteristics of casein,casein was self-assembled to obtain uniform micelles,and a new nanocomposite crosslinker was prepared by metal-nonmetal coordination.The morphology and structure of the crosslinker were investigated by TEM,EDS,DLS and RS.With the addition of monomer and initiator,a three-dimensional polyacrylamide hydrogel network was constructed under the action of ultraviolet light.The pore size,distribution and structure of the gel were evaluated by SEM,EDS,FTIR and other techniques.(2)The effects of cross-linking agent composition(casein and silver nitrate)on the properties of hydrogels were investigated by using tensile strength and adhesion strength as the indexes of mechanical properties and adhesion properties,and the optimum dosage was selected.The self-repairing performance,notch insensitivity and swelling ability of hydrogels were evaluated by self-repairing efficiency,fracture toughness and swelling ratio.(3)The antifreeze hydrogel was constructed by using binary solvent ethylene glycol/water as gel dispersant.The effect of ethylene glycol content on the properties of hydrogel was investigated by tensile strength and adhesion strength.The effects of temperature on the mechanical toughness,electrical conductivity and sensing accuracy of the hydrogel were evaluated with the changes of tensile strength,adhesion strength and relative resistance.(4)The cytocompatibility and transdermal delivery ability of hydrogel were evaluated by cell experiment and transdermal test in vitro.Results:(1)In this study,Casein could be assembled in aqueous solution of p H=11～12to form spherical micelles with negative charge on the surface.Ag~+could be bound to the surface of Casein spherical micelles through electrostatic interaction,and BACA could be further bound to the surface of Casein@Ag~+composite spherical micelles through Ag-S metal coordination to form Casein@Ag~+@BACA nanocomposite crosslinking agent,adding monomers and photoinitiators.Nanocomposite hydrogels with uniform size and network structure could be obtained under the action of ultraviolet light.(2)When the mass fraction of casein was 15 wt%and the amount of silver nitrate was0.05 mg,the prepared CAP hydrogel showed the strongest tensile properties(fracture stress:3.7 MPa,fracture strain:1600%)and adhesion strength(the adhesion strength to pigskin was 28 KPa).The existence of metal coordination bonds and a large number of hydrogen bonds given CAP hydrogel self-repairing properties,and the self-repairing efficiency could reach 55%and 36%under the stimulation of microwave and p H,respectively.(3)On the basis of CAP hydrogel,ethylene glycol was introduced to form antifreeze hydrogel.When the volume ratio of ethylene glycol to water was 1:6,CAEP hydrogel had certain strength,viscosity,moisturizing and anti-freezing ability,and its electrical conductivity and sensing properties were not affected by temperature.It had a good sensibility in the range of 0-1000%and could be used to monitor all kinds of human sports behavior.(4)The results of cytotoxicity test in vitro showed that the hydrogel had good cell compatibility,and the results of transdermal test in vitro showed that the hydrogel had a stable and sustained drug release effect as a transdermal drug delivery vehicle.Conclusions:In this study,we successfully constructed a new nanocomposite crosslinker based on casein self-assembly,electrostatic interaction and dynamic reversible silver-sulfur metal coordination bonds.The nanocomposite hydrogels prepared by this crosslinker had excellent mechanical properties,adhesion properties and self-repairing properties.In the aspect of biological flexible sensors,after the introduction of ethylene glycol,the nanocomposite hydrogel had excellent temperature tolerance,excellent sensing performance and human behavior monitoring ability in the range of-20℃-60℃.In the aspect of drug delivery,the hydrogel also showed excellent cytocompatibility and could be used as a drug sustained release preparation to realize the slow transdermal release of colchicine. |
PDF Full Text Request