Preparation And Properties Of Bionic Articular Cartilage Hydrogel Based On Lipid Lubrication

Articular cartilage is a kind of connective tissue with high gradient layered structure,which can buffer the vibration and impact generated by human movement.It is difficult to heal after injury due to there are almost no blood vessels and nerve tissue around the articular cartilage.Traditional artificial articular cartilage materials mainly include metal materials,inorganic ceramic materials and synthetic polymer materials,but they are not ideal artificial articular cartilage implant materials.For example,metal materials are easy to corrode,inorganic ceramic materials are easy to crack,and synthetic polymer materials are easy to wear.The structure and properties of hydrogels are similar to those of articular cartilage,with three-dimensional network structure and excellent biocompatibility.Hydrogels have great potential in biomimetic articular cartilage materials.Therefore,three kinds of bionic articular cartilage hydrogels were synthesized in this paper.The main research contents are as follows:（1）Carbon quantum dots（CQDs）were synthesized by high temperature and high-pressure hydrothermal method using sucrose and concentrated sulfuric acid as raw materials.Then CQDs chitosan/poly（acrylamide-co-acrylic acid）-Fe³⁺hydrogels were synthesized using CQDs as nano fillers,and the physical and chemical properties of the hydrogels were characterized.The morphology and functional groups of CQDs were characterized by TEM and FTIR,which showed that CQDs had a graphite like crystal structure and rich in oxygen-containing functional groups.In the mechanical property test,the hydrogel showed excellent mechanical strength:the tensile stress was 6.85 MPa when the fracture tensile strain was 312%.The UV-vis spectra showed that the CQDs in the hydrogel and the carboxyl group on the polymer chain of poly（acrylamide-co-acrylic acid）reacted with Fe³⁺,giving the hydrogel good mechanical properties and self-healing properties.The dynamic rheological property test shows that the hydrogel can withstand the periodic dynamic changes of human body.Swelling experiments show that the hydrogel has good swelling resistance in a wide p H range and under different solute conditions.In vitro hemolysis experiments showed that the hydrogel had low hemolysis rate,which met the requirements of medical materials,indicating that the hydrogel has good biocompatibility and has a wide application prospect in biomimetic articular cartilage materials.（2）Agarose/polyvinyl alcohol-DMPC-sodium citrate hydrogel was synthesized by using agarose,polyvinyl alcohol and 1,2-dimyristoyl-sn-glycero-3-phosphocholine（DMPC）materials.In addition,water/dimethyl sulfoxide was used as the mixed solvent.The hydrogel has good mechanical properties,friction properties and biocompatibility.The results show that the compressive stress is 5.52 MPa when the compressive strain is 75%and the tensile stress is 10.11 MPa when the tensile strain is 1400%.The hydrogel can withstand the daily activities of human joints and shows excellent mechanical properties.Friction experiments showed that the friction coefficient of the hydrogel was only 0.027 after DMPC was added,which was lower than that of most hydrogel materials.The hydration and lubrication of phosphatidylcholine head group of DMPC played a key role.In vitro experiments show that the hydrogel has good blood solubility and low cytotoxicity to cells.It can be used as a candidate material for bionic articular cartilage.（3）Using CQDs as hard template and cetyltrimethyl ammonium bromide as soft template,then adding phosphorus source and calcium source to synthesize mesoporous hydroxyapatite（HAP）nanomaterial,and then loading anti-inflammatory drugs into HAP.Furthermore,the agarose/poly(acrylamide-co-N-（2-hydroxyethyl）-DMPC-HAP hydrogel was synthesized by freezing-UV irradiation with agarose,acrylamide,N-（2-hydroxyethyl）-acrylamide,DMPC and HAP hydrogel.The hydrogel has good mechanical properties and drug loading performance.The results show that the hydrogel has excellent mechanical properties.The compressive stress is 5.12 MPa when the compressive strain is 75%,and the tensile stress is 3.11 MPa when the fracture tensile strain is 470%.Dynamic rheological tests showed that the rheological behavior of the hydrogel under shear force was similar to that of natural articular cartilage.At low load,the friction coefficient of the hydrogel after adding DMPC is0.057,indicating that DMPC has good hydration lubrication performance.Using Curcumin（Cur）as the model drug,the encapsulation rate and drug loading rate of HAP@Cur nanoparticles reached 21.5%and 4.3%at 37℃,indicating that HAP has a good drug loading capacity.The hydrogel has good biocompatibility and provides theoretical guidance for the replacement of natural articular cartilage.