Preparation Of Injectable Supramolecular Polymer Hydrogels And Exploration As Artificial Vitreous Body

When biomaterials are implanted in vivo,they tend to trigger the foreign-body reaction,such as inflammatory and fibrosis reactions,thus resulting in transplant failure and affecting the service life of the transplanted materials in vivo.To mitigate the foreign-body reaction,we constructed various injectable supramolucular polymer hydrogels with excellent biocompotibility in this work.A supramolecular copolymer hydrogel was first prepared by one-step copolymerization of N-arolyoyl glycinamide(NAGA)and 1-vinyl-1,2,4-triazole(VTZ)without any chemical cross-linker through UV photo-initiation.The dual amide in side chain of NAGA could form stable multiple hydrogen bonding domains,serving as physical crosslinkages of this supramolecular polymer hydrogel.More importantly,triazole residues served to endow the obtained hydrogels with antibacterial and anti-inflammatory activities.This hydrogel exhibited excellent mechanical properties-high tensile strength(?1.2 MPa),large stretchability(?1300%),and outstanding compressive strength(?11 MPa).Furthermore,computer simulation indicated that the introduction of VTZ component weakened the hydrogen-bond interaction within the network.The equilibrium water content(EWC)was increased because more H₂O molecules could penetrate into the network.Such dynamic hydrogen bonds could be dissociated at high temperature(?70?)and reformed at room temperature,rendering this hydrogel self-healable,remoldable,thermoprocessable.The gel-sol transition temperature of PNAGA-PVTZ hydrogel was too high to be injected directly into the organism.The animal experiments indicated the fibrosis reaction around the implanted hydrogel.Further,a supramolecular binary copolymer hydrogel termed as PNAGA-PCBAA by copolymerization of N-acryloyl glycinamide and carboxybetaine acrylamide(CBAA)was prepared.The introduction of CBAA component could improve the biocompatibility of hydrogel and endow the hydrogel with anti-fouling,anti-inflammatory and anti-fibrosis.Dynamic hydrogen bonds within the network contributed to self-healability,shear-thinning behavior,and rapid network recoverability.The hydrogel had a super water absorbent(98.4%)and was still stable with a lower initial monomer concentration(10%)and monomer ratio(4/1).In addition,such hydrogel exhibited self-healability at body temperature,shear-thinning behavior and rapid network recoverability,which was beneficial for the injection into the living organisms.Most remarkably,the biomechanical,physical and optical properties of the PNAGA-PCBAA hydrogel were very close to key parameters(modulus-10 Pa,light transmittance-93.2%,refractive index-1.3354,EWC-98.4%)of human vitreous body,which have not yet been achieved as an artificial vitreous body by any reported work.The hydrogel was injected into the vitreous cavity of the rabbits as vitreous substitutes.The animal results indicated the hydrogel was an ideal artificial vitreous substitute without affecting the structure of soft tissues in eye,or eliciting adverse effects after 16 weeks implantation.When the monomer concentration and ratio were raised to 35%and 13/1,respectively,the obtained hydrogels achieved 1.13 MPa tensile strength,1200%elongation at break and 9 MPa compressive strength.This high strength supramolecular polymer hydrogel is promising to be applied as load-bearing soft tissue substitutes.