Research Of 3D Bioprinting Stereolithography Process

3D bioprinting,as a new means of tissue engineering,has played an increasingly important role in three-dimensional in vitro cell culture,organ chip manufacturing,drug screening,tissue regeneration and other aspects.By 3D printing technology,cells can be accurately shaped into the designed three-dimensional structure,which is the closest approximation way to make the real biological tissue,and it is the best hope for human beings to overcome diseases and aging defects.In order to allow cells to better extend and multiply in the hydrogel model,two core problems need to be solved from the perspective of biological manufacturing :(1)selection of bio-inks with excellent biological compatibility and printing performance.(2)to find a 3D printing method suitable for this ink and explore its corresponding printing technology.GelMA,as a modified gelatin,has been widely used in the fields of biological manufacturing and tissue engineering,and has been proved to be an excellent photosensitive material with both biological compatibility and printability.For traditional extrusion bio-3d printing,the mainstream printing method requires GelMA to be mixed with other materials or modified before printing.In this paper,a new photocurable printing method is proposed,which can directly print GelMA hydrogel with low substitution rate and low concentration.Through a detailed study of the photocuring process,this paper explores a precise for printing method of photosensitive hydrogel,and makes a systematic quantitative study of the specific printing process.In this paper,these complex structures that are difficult to be realized by traditional 3d printing methods of biology are made,and further exploration is made for more biocompatible in vitro cell growth environment.1.The forward photocurable 3D printing platform was built.The high-precision deceleration module and 200 m W blue light laser generator were used to build the hydrogel temperature control platform.Through the control of the upper computer,two kinds of hydrogel models,two kinds of two-dimensional model and three kinds of three-dimensional model,can be manufactured.2.The mechanism of photocuring was studied systematically.Firstly,the processes of double bond breaking,free group generation and long polymer chain connection were discussed.Secondly,the rheometer is used to quantitatively and intuitively understand the photocuring process.Finally,the self-built photocurable biological 3D printer was used to systematically study the photocurable 3D molding process,define and extract the important characteristic values related to printing,and summarize the influence of light time,GelMA concentration and other parameters on printing.3.The structures that are difficult to print were reconstructed by hydrogel photocuring according to different biological meanings.Through the selection of different "printing Windows",the manufacturing of different porosity grids,built-in nutrient channels,thin-walled bodies and high-inclination structures can be realized.These structures play an important role in cell and biological manufacturing,but the traditional biological 3D printing method is difficult to achieve.4.The biological compatibility of photocurable biological 3D printing was studied.In order to prove that cells can grow well in the hydrogels made in this paper,the threedimensional hydrogels containing cells made above were used to conduct in vitro cell culture experiments using mouse bone marrow mesenchymal stem cells(m BMSCs).Cell growth on and within hydrogels was evaluated by the characterization of cell viability,skeleton and migration.The results showed that because of GelMA's good biological compatibility and reasonable hydrogel structure,the cells suffered less damage and had a better growth environment,thus had a higher proliferation rate,cell activity and a better growth state.