Preparation Of Silk Fibroin-based Bioinks For Three-Dimensional Printing Applications

Articular cartilage injury is one of the most difficult diseases in the clinic and has a high incidence.Trauma,improper exercise,and increased age are all risk factors for knee injury.Cartilage is a common injury site of the knee joint,which can cause damage to the knee joint function and directly affect the daily activities of the patient.The transplantation of tissue engineering cartilage substitute is a common treatment strategy.Individualized differences of patients are one of the key factors affecting the repair effect for constructing cartilage implants.3D printing is a precise and rapid additive manufacturing technology.The combination of 3D printing technology and construction of tissue engineering scaffold has opened up a new path for improving clinical repair efficacy.However,at present the lack of 3D printing "bioinks" materials that applied in cartilage tissue engineering limits its development and application,so it is particularly important to develop a suitable 3D printing bioinks for tissue engineering.In recent years,hydrogels have attracted great attention in the biomedical field due to their similar physical and chemical properties to extracellular matrices(ECM).Compared with other synthetic biomaterials,natural polymer hydrogels are closer to living tissue,possess higher water absorption rate and can reduce the friction on surrounding tissues.At the same time,the hydrogel exhibits good biocompatibility and can be used as an active matrix to control cell morphology,proliferation and differentiation.Therefore,hydrogel-like biomaterials have a promising application prospect in soft tissue regeneration.In this study,we developed a composite 3D printing bioinks based on silk fibroin material and constructed a cartilage biomimetic scaffold.The fabricated bioinks consist of modified silk fibroin and modified gelatin,and a hydrogel biomimetic scaffold suitable for cartilage transplantation is explored and prepared by 3D printing technology.We conducted a series of studies on the synthesis of inks developed and the physical and chemical properties and biocompatibility of the prepared stents,which mainly comprising the following aspects:(1)Firstly,silk fibroin and gelatin grafted with photosensitive groups were synthesized separately,and the structure and grafting efficiency of the target product were investigated.The experimental results show that the modification of silk fibroin with glycidyl methacrylate can maximally utilize the extremely limited lysine on silk fibroin to successfully prepare the target product.(2)Preparation and UV-crosslinking of composite hydrogels using modified silk fibroin(SilMA)and gelatin(GelMA),investigate the impact of different modified silk fibroin(SilMA)content on hydrogel physical and chemical properties.The experimental results show that the pore size and swelling ratio of the composite hydrogel decrease with the increased content of SilMA,the while mechanical properties exhibit reverse tendency,and the content of SilMA has a slight influence on the crosslinking point,which is resulted from the constraints of internal structure between SilMA and GelMA.(3)Construction of a biomimetic scaffold using a synthetic SilMA-GelMA composite 3D printing bioinks.The effects of different parameters,including grid filling widths,needle diameters and other printing parameters,on the construction of bionic scaffolds were explored and the vitro and in vivo biological effects were evaluated.Cell proliferation experiments showed that bone marrow mesenchymal stem cells(BMSCs)can adhere and grow on the SilMA-GelMA 3D printed bionic cartilage scaffold.Subcutaneous implantation experiments in rats demonstrated that the scaffold has good biocompatibility,and the cells can grow into the inside of the scaffold within one week without causing an inflammatory reaction.In summary,the SilMA-GelMA composite bioinks prepared in this study can be well applied to tissue engineering 3D printing technology,can print a variety of personalized stents,especially suitable for transplantation and repair of cartilage damage.The combination of 3D printing technology and hydrogel tissue engineering scaffolds provides new insights for therapeutic strategies in the biomedical field.