Study On Biohydrogel Projection UV Curable Printing Process And Its Application In Breast Reconstruction

Projection light curing(digital light processing)has advantages such as high printing accuracy and fast molding efficiency,and is widely used in tissue repair and reconstruction.However,this printing method relies heavily on biological materials,so it is necessary to develop biological inks with good fluidity and high efficiency light curing ability.In this paper,a photocurable biological ink(F127DA)was prepared,which has good fluidity and high molding ability.The physicochemical properties of the prepared ink and the process parameters affecting printing accuracy were systematically studied.Prosthesis implantation and fat transplantation are commonly used methods of breast reconstruction.The appearance of implant alone is not realistic,and fat transplantation alone is difficult to achieve sufficient capacity.In order to achieve good results,the combination of the two ways is often used in clinical practice,but it needs to be implemented in stages.There is no report on the method of combining fat and prosthesis implantation.Based on the designed bionic ink(F127DA&PEGDA)and projection photocurable printing technology,a new method for printing porous prostheses was developed.The specific contents of this study are as follows:(1)Chapter 2 studies the properties of UV curable inks.Firstly,F127 was modified to have the ability to UV curable.The end chain of F127 was grafted with carbon carbon double bonds through the reaction with acryloyl chloride to have the characteristics of light response.Nuclear magnetic testing was conducted to determine whether to graft carbon double bonds.Secondly,some performance tests were conducted on F127 DA to further prove its photocurability and pave the way for exploring suitable printing conditions.The rheological and physical properties of F127 DA were tested respectively.The viscosity and temperature sensitivity in the rheological test are to prove that F127 DA does not destroy the characteristics of F127 itself and has good fluidity at specific temperatures.The UV curing modulus simply determines the exposure time for printing,as well as the UV curing modulus.Physical properties include swelling test,porosity of hydrogel and mechanical properties.Without swelling and proper compression modulus,it is very suitable for prosthesis materials.Thirdly,PEGDA was added to reduce the impact of external temperature on the fluidity of the material,and the rheological properties of the added PEGDA were tested to determine the range of printing parameters.This part of work shows that the prepared F127 DA can not only be used as 3D printing hydrogel material alone,but also has a wide range of application scenarios due to its superior physical properties.This part also provides a reference for printing parameters for the next chapter.(2)Chapter 3 focuses on printing accuracy,mainly studying the factors that affect printing accuracy from three aspects: process parameters,hardware,and materials.Software: The main research objects are layer height,light intensity,and exposure time.Since the setting of light intensity has been determined during rheological testing,it is only necessary to change the layer height and exposure time to observe the impact on printing accuracy,which are complementary.Hardware: Hardware mainly studies the light transmittance of the material trough,mainly through comparing the projection of light glass and ground glass.In order to explore the difference between transparent glass and ground glass printing,a light transmittance test was conducted on the material trough.The material trough was placed under a microscope and irradiated with 405 nm light to measure the image of its projected focal plane.Comparing the projection results and printing results of the two,it was ultimately found that the printing accuracy of the light glass trough was higher.Materials: The research objects include the material ratio of light absorbers and photoinitiators,and the concentration of PEGDA.Both photoinitiators and photoabsorbers complement each other.As the concentration of photoabsorbers(LAP)increases,the required exposure time decreases,and the higher the concentration of LAP,the more obvious the effect.This is because as the concentration of LAP increases,the deeper the light can penetrate,the faster the initiation efficiency,and the less exposure time is required.The best printing ratio selected is 0.2% LAP+0.1% lemon yellow+3% PEGDA and 0.5% LAP+0.2% lemon yellow+3% PEGDA.(3)The fourth chapter focuses on breast reconstruction research,and develops a porous prosthesis based on a projection type photocurable printing process.Using a combination of autologous fat filling and prosthesis reconstruction to achieve breast reconstruction can not only ensure the aesthetic appearance of the breast,but also solve the problem of "poor" autologous fat.Firstly,the biocompatibility of the material was evaluated and it was determined that 15% F127DA&3% PEGDA were suitable for breast reconstruction.Subsequently,the porous prosthesis was printed and tested for compressive modulus.Finally,the injected SVF-Gels were injected into the porous prosthesis,and then implanted into the back of mice to create a model.Finally,the success rate of the experiment was judged by evaluating the survival of fat.The experimental results show that this porous prosthesis with pre embedded adipose tissue is a promising breast reconstruction material.