Study On Processing And Mechanical Propertiesanalysis Of Degradable Micro-bioscaffolds

Micro bioscaffolds are three-dimensional structures that support damaged parts and deliver nutrient products for cell growth in the medical field,and are an important part of the field of regenerative medicine.Among them,bone tissue engineering scaffolds have been used for a long time and are widely used in fields such as disease treatment,surgery and tissue engineering,and have great application prospects.Gel-MA hydrogel is a modified material of natural gelatin,which not only has excellent biocompatibility and degradability of natural gelatin,but also maintains a good level of mechanical properties.Two-photon polymerization technology is a micro-nano processing technology with nano-resolution and high three-dimensional controllability.Using two-photon polymerization processing technology to process degradable bone tissue engineering microscaffolds is an effective way to process more precise microscale bioscaffolds.Therefore,it is of great significance to conduct research on degradable bioscaffolds.Bone tissue engineering scaffolds are composed of each micro-scaffold array,and today they are still faced with problems such as simple support and no response after being loaded,low processing accuracy,and poor biocompatibility.In order to solve the above problems,this paper has carried out the following work:(1)Structural design and Simulation of micro support.By analyzing the mechanical properties of traditional micro stent and double spiral micro stent,the displacement and stress of the stent after loading are obtained.Compared with the two after loading,the "Tian" spring like bone tissue engineering micro stent is designed,and the mechanical properties and modal analysis simulation are carried out.(2)Two-photon polymerization processing of Gel-MA hydrogel and preparation of micro-scaffolds.Using Gel-MA as the monomer,LAP was improved and selected as the photoinitiator of this experiment,and a biocompatible and degradable photoresist that could be used for two-photon polymerization processing was prepared.Using the two-step cross-linking characteristics of Gel-MA hydrogel to improve the two-photon polymerization process,the relationship between the micron linewidth of Gel-MA hydrogel,laser power and scanning speed was explored.By analyzing the relationship between the three,processed the plane,wedge-shaped structure and wood pile structure,and successfully realized the two-photon polymerization of Gel-MA hydrogel to process the micro-nano structure;according to the problems encountered during processing,the laser power,scanning speed,layer thickness,etc.were optimized.Based on the basic parameters,the "Tian"-shaped micro-bracket was processed with the best processing parameters.(3)Mechanics,biocompatibility and degradability testing of micro bioscaffolds.The ultimate compression resistance of the fabricated scaffolds was tested by nanoindenter.NIH/3T3 cells were used to check cell viability after resuscitation,passage,storage,concentration adjustment and seeding,and cells were stained with Calcein/PI kit,the cell fusion rate was above 80%,the MTT solution was added for culture and centrifugation,and then the DMSO solution was added to dissolve,and the cell proliferation was detected.After 48 hours,the cells obviously began to proliferate.Using type B collagenase,different concentrations of collagenase solutions were prepared and added to the processed cuboid structure and the "Tian"-shaped scaffold structure,respectively,and the effects of different concentrations of collagenase,different sizes and different structures on the degradation were explored.