Preparation And Properties Of Silk Fibroin/hyaluronic Acid Blend Hydrogels

Hydrogel has the advantages of good water retention, shape preserving and so on. It can provide good anchor point for the cell, and can be used as growth factors or drug’s carrier by its internal three-dimensional network structure. Because of this, it has become the hot spot of research in the field of biomedical materials. Human soft tissues(such as skin and spinal cord) is a typical colloid system, mainly consisting of protein and polysaccharides, such as spinal extracellular matrix contains a large number of hyaluronic acid(HA). This paper imitates the composition and structure of the spinal cord in the extracellular matrix, used silk fibroin(SF) which has good biocompatibility and hyaluronic acid(HA) as raw material, prepared the composite gel quickly which has good mechanical properties, and it provides a kind of new material for the repair of spinal cord nerve.This paper prepares SF/HA composite hydroge, through the synergy of chemical crosslinking and physical function. Adding cross-linking agent 1-ethyl-(3-Dimethyl aminopropyl) carbodiimide(EDC) / hydroxy acyl imine(NHS), change the gel temperature and the proportion of SF/HA composite hydrogel, optimize the forming time of composite gel. The results showed that with the increase of temperature, the time of gelation gradually shortened, the ratio of SF/HA has little effect on the gel forming time. In addition, EDC has an obvious effect on the crosslinking of SF/HA composite gel, it makes the composite gel water dissolved rate decreased significantly. Then study the mechanical properties of SF/HA composite gel by testing and analyzing it’s water absorption, porosity, contact angle, mechanical properties. The results showed that with the increase of HA content, the water absorption, porosity and failure strain increased gradually, the contact angle decreased, and the compressive strength increased first and then decreased. Further, the scanning electron microscopy(SEM), infrared spectroscopy(IR), raman spectra and X-Ray diffraction(XRD) were employed to investigate the structure of the composite gel. The study showed that the composite gel was mainly amorphous structure, and contained a small amount of β-sheets, and with the increase of HA content, the content of β-sheets gradually decreases.Finally, through the optimization of the performance indicators, to determine the optimal ratio of SF/HA composite gel was 5/5. In this ratio,composite gel has good water absorption performance, and has good mechanical properties. In vitro degradation and drug release studies showed that under the action of alpha protease, the hydrogel’s degradation rate can reach 50% after 18 days, proved it has good biodegradability. Then use rhodamine B as a model drug, and its early release quantity is larger, the late sustainable slow release, in the accumulation of 38 days drug release a quantity to reach 80%, proved that it can be used to build drug control-released carrier. This study provides the theory basis for the construction of soft tissue regeneration materials such as spinal cord repair material and corneal repair materials.