Combining change and constant balance: changing biomedical 3D printing
At the first Regenovo Bio 3D Printing Academic Forum, Professor Xu Shanhui, Director of Tissue Engineering and 3D Printing Center of Taiwan University, shared some of his team's research results on 3D bioprinting of waterborne polymer materials.
There are many 3D technologies in the industry, but not all can be applied to biomedicine. Therefore, in addition to using some hard tissue materials in biomedicine, it is some laser technology. The most common organic materials are SLAFDM and LFDM. The simplest method is extrusion molding. The general 3D printing materials can be roughly divided into two categories: inorganic materials and organic materials. Today I mainly focus on the organic materials.
The emergence of low temperature processing waterborne materials
The advantage of organic materials is that there are many processing methods. Currently, the most widely used in the industry is polylactic acid (PLA) and acrylonitrile-butadiene styrene (ABS). The difference is that ABS cannot be decomposed.
Polymer 3D printing material is the most popular ABS, his processing performance is very good, but his problem is that its general processing method is high temperature, there will be taste when printing, this taste is related to his volatility, so in recent years Less popular than PLA. If processed at high temperatures, both PLA and PCL will be hydrolyzed, so the printed matter is different from the raw materials, which limits the application in the medical field. Therefore, we decided to use PLA without high temperature to do PLA and PCL in 2001. Printing, because the degree of hydrolysis of the raw materials is different after printing. So we changed to a solvent method and processed it at low temperatures.
The advantage of the polymer is that in addition to melt processing, it can also be processed with a solvent. The solvent can be used at low temperatures, but most of the solvent is toxic. The solvent for PLA and PCL usually has 1,4-dioxane. Dichloromethane, chloroform. Water-based printing materials are environmentally friendly, not only environmentally friendly, but also safe for the human body. Do not worry about the safety of residual solvents when the bioprinting support has high porosity.
Among the commonly used water-based printing materials, natural polymers are chitosan, gelatin, etc. Chitosan is formed by liquid cryoprecipitation, but its properties are brittle. Gelatin is formed by photocuring. The advantage of curing with light is that it is easy to form. However, there will be free radicals. If the cells are printed, different cells eat different degrees of free radicals. Therefore, after the system is changed, the cells need to be adjusted, and the survival rate of the cells is affected by free radicals. Synthetic polymers are PEG and pluronic, which have the advantage of flexible modification, but they are not biodegradable and can only be dissolved, so they can be dissolved only in small molecules and then excreted.
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