Construction And Evaluation Of Sodium Alginate Based Hydrogels For Tissue Repair Application

Hydrogels are widely used in tissue engineering and biological medicine due to their high water content,physical properties similar to the extracellular matrix(ECM)and could simulate the human body's organizational structure.With the development of scientific technology,higher requirements were proposed on hydrogels.Ideal hydrogels could not only provide supporting for defect site,but also be a part of the body to participate in the life activities,thus realizing the tissue repairment and reconstruction.Therefore,it's very important to study the tissue engineering combined cytokines with biomaterials.The microparticles had good properties in drug delivery system;they could encapsulate drugs to avoid the inactivation and could realize sustained release drugs.So the functionalized hydrogel systems were prepared by integrating microparticles into hydrogels.In this paper,on the basis of the bionic,we committed to the preparation of microspheres composite hydrogels with good comprehensive properties.The work played an important and significative role in the design and preparation of composite hydrogel scaffolds.The natural materials were modified to get aldehyde groups and amino groups,upon mixing the two components together schiff's based reaction occurred and then hydrogels formed quickly.The swelling behaviors of hydrogels were associated with aldehyde content and amino content,with the increase of the amount of crosslinking groups,a denser network structure formed and the swelling ratio decreased.In the process of the preparation of the hydrogels,there were no toxic crosslinking agents introduced,so the hydrogels had good biocompatibility,safety and reliability.In addition,the prepared hydrogels have good adhesive strength which equal to the commercially available adhesive Fibrin glue.So,these hydrogels in this study could be a promising candidate as soft tissue adhesive.In order to prepare hydrogels with not only good biocompatible but also good mechanical properties,aldehyde sodium alginate(ASA)was chosen to further graft methacrylate groups on the main chain of ASA to form AMSA,then mixed AMSA and AG aqueous solutions.Firstly the schiff's based reaction occurred quickly to form the primary network between aldehyde groups in AMSA and amino groups in AG,and then a 365 nm ultraviolet(UV)light was used to initiate the radical reaction of methacrylate groups in AMSA to produce the secondary network.This double crosslinking network hydrogels had higher crosslink densities,lower swelling ratios and improved mechanical properties compared to the single schiff's based networks hydrogels.The in vitro cytotoxicity activity of cells on the hydrogels surface tests showed that the double network hydrogels are more suitable for tissue repair.Furthermore,the hydrogels could provide the suitability environment for cell growth not only on the surface but also into the inner after the modification of RGD.Furthermore,for the purpose of hydrogel has a better effect in tissue repair and reconstruction.Here we construct a functional composite hydrogels systems which integrating the polyurethane nanoparticles into AMSA/AG photocrosslinked double network hydrogels.Firstly,amphiphilic polyurethanes containing amino groups were prepared by PEG as the main material.These polyurethanes could be self-assembled to nanoparticles in water,and the properties of nanoparticle could be controlled by changing the molecular weight of PEG and the ratio of hydrophilic to hydrophobic segments.It had good biocompatibility and could loading drugs.In addition,the amino group of the polyurethane can also graft small molecule drug KGN(Kartogenin).Then the prepared polyurethane nanoparticles were integrated the hydrogels,these composite hydrogel combined the drug delivery characteristics of nanoparticles and the injectability of hydrogels,it has the potential as a candidate of cartilage repair and regeneration.