Structural Design And Biomedical Properties Of High Strength And Toughness PHEMA-based Hydrogels

Hydrogels are widely used in the field of biomedical materials because of their adjustable mechanical properties,good biocompatibility and similar modulus to natural soft tissue.However,most of the biocompatible hydrogel materials have poor mechanical properties that are difficult to meet the application requirements of high loads such as articular cartilage and internal scaffolds.Therefore,it is great significance to design a hydrogel material with high strength and good biocompatibility.In this paper,a series of hydroxyethyl methacrylate（HEMA）and maleic acid（MA）hydrogels with biocompatible and excellent mechanical properties are prepared by constructing different cross-linked networks,which can be used in biomedical applications.The main contents of this paper are as follows:（1）By polymerization of HEMA and MA,a strong hydrogen bond network is constructed to improve the mechanical properties of PHEMA-based hydrogel,in which compression modulus（48.81 k Pa）corresponding to commercially available silicone breast prosthesis materials.In addition,the hydrogel has good energy dissipation ability,self-recovery ability and fatigue resistance ability through cyclic compression.At the same time,the hydrogel has good biocompatibility through in vitro and vivo biological experiments.These characteristics demonstrate the potential of the hydrogel as breast prosthesis material.（2）In order to further improve the mechanical properties of PHEMA-based hydrogel materials and broaden their application in tissue scaffolds or cartilage materials.Fe³⁺are introduced into PHEMA-based hydrogel system to form robust coordination in this experiment.This coordination suppresses phase separation of PHEMA chains from aqueous solution,thereby inducing a homogeneous network.The homogeneous network can avoid stress concentration,and robust coordination crosslinking can effectively dissipate energy and maintain network elasticity simultaneously.The synergistic effect of these two factors imparts the hydrogel with exceptionally high tensile strength（3.44 MPa）,elastic modulus（14.22 MPa）and toughness（4.17 MJ/m~3）.Such mechanical properties are comparable to human nasal and auricular cartilages.Moreover,the hydrogels manifest outstanding self-recovery properties and fatigue resistance.Based on features,the hydrogels provide a new platform for the nasal and auricular cartilage substitution.（3）In order to impart PHEMA-based hydrogel with excellent anti-swelling performance in humid physiological environment.N,N’-methylene bisacrylamide（MBA）chemical crosslinking is introduced on a series of strong and tough PHEMA-based hydrogels prepared previously,so as to prepare the physicochemical hybrid crosslinking hydrogel network.Such network endows the hydrogels with outstanding mechanical properties,in which the tensile strength is up to 2.42 MPa and elastic modulus is up to 3.32 MPa,superior to many reported PHEMA-based hydrogels.Meanwhile,the hydrogel possesses stability and anti-swelling.Then,the hydrogel is combined with estradiol-loaded silica to prepare PHEMA-based hydrogel with high strength and toughness.More importantly,these drug-loaded hydrogels release estradiol continuously and stably,and have a good therapeutic effect in promoting the growth of endometrial cells.Therefore,the tough and stable hydrogels show promising potential in intrauterine adhesion（IUAs）treatment.