Research Of SA/AAM Controllable Hydrogel Based On PBP Technology

Photoresponsive hydrogels are particularly advantageous in many applications due to the non-contact remote control,inherent spatiotemporal control capability of biomaterials.Because light is non-invasive and can be manipulated remotely without the assistance of other reagents,the by-products produced are limited,and spatial control can be achieved in both two and three dimensions due to the inherent properties of light,such as wavelength and intensity,which can be adjusted.Aiming at the effect of light stimulation,this paper explores the process of preparing a curved blood vessel model based on the deformation of sodium alginate（SA）/acrylamide（AAM）hydrogel based on projection-based 3D bioprinting（PBP）technology.This study provides a method to fabricate a curved blood vessel model based on photostimulus-responsive hydrogels based on the PBP technique.The main research contents and conclusions are as follows:1.Rheological test was used to compare the viscosity of SA/AAM hybrid hydrogel with different molecular weight and different concentration ratios.It was found that the viscosity of the hydrogel increased with the increase of the molecular weight of SA.The printing process requires that the bio-ink has a low viscosity and can quickly recover to cover the printing area.SA with molecular weight of 98K was selected as one of the monomers of the mixed bioink to meet the requirements.Therefore,the rheological test and compression test of SA/AAM hybrid hydrogel with different concentration ratios were carried out.It was found that after the completion of photopolymerization,the storage modulus（G’）was significantly greater than the loss modulus（G"）,indicating that the bioink could undergo rapid photocuring.The higher the AAM concentration,the greater the G’of the hydrogel.The material characterization of SA/AAM hybrid hydrogel was systematically studied and analyzed.It was found that the storage modulus of SA/AAM hybrid bioink with molecular weight of 98K and concentration of 30wt%and the concentration of 30wt%was 90.157KPa and the viscosity was 0.013Pa.s.The optimized material ratio not only meets the needs of the printing process for bioink,but also has good mechanical properties for subsequent experiments.2.A test aperture size model was constructed to explore the influence of printer light intensity,layer thickness and exposure time on the print aperture size.According to the influence of printing parameters on the print aperture size,two experiments were designed to explore the relationship between exposure time and layer thickness after fixed light intensity and the relationship between exposure time and light intensity after fixed layer thickness.By matching the change of printing parameter conditions with the printing accuracy,a range of printing parameters that can be referred to is obtained,and the optimal printing parameters are obtained through the multi-channel structure with a printing aperture of 200μm for subsequent research.3.3.FTIR verified that there are a large number of free carboxyl groups in the molecular chain of SA/AAM hydrogel that can coordinate with metal ions.XPS and EDS determined the necessary factors for the deformation of SA/AAM hydrogel in response to light stimulation by testing the content of Fe³⁺and Fe²⁺ions at different stages.The carboxyl group in the hydrogel can bond with Fe³⁺ions after the printed sample is immersed in the Fe Cl₃ solution.The Fe³⁺ions can be introduced into the SA/AAM hydrogel,and Fe³⁺ions can be partially converted to Fe²⁺ions under ultraviolet light.By establishing a deformation standard based on the vascular model,the deformation standard is used to explore the influence of the concentration of crosslinker,the concentration of soaking Fe Cl₃ solution,and the time of soaking Fe Cl₃ solution on the deformation performance of light stimulation response,the relationship between material concentration,time and deformation performance is obtained,and the deformation conditions of the optimal deformation performance are obtained.4.After preparing blood vessels based on PBP technology,according to the controllability of light and multi-point control,illumination in different directions at different points of the long blood vessel revealed that the blood vessel presented"S"shape,and ultraviolet light irradiation was performed on the bifurcation blood vessel to find that it had light bending.Then,the single-channel blood vessels were subjected to different post-treatments of soaked Fecl₃solution,and soaked Fecl₃ solution followed by light.The cells were cultured on the two groups of blood vessels,and the cell activity was observed and verified.The overall cell activity was high.This study not only verified that Fe had no toxic effect on normal cells,but also showed that SA/AAM bioink had good cytocompatibility.