The selection of materials known to be biocompatible is the starting point for the assessment. There are many 3D printed materials on the market that are specifically designed for biological applications, and these materials are often rigorously tested and certified. For example: Biocompatible resin: suitable for SLA or DLP printing, often used in the manufacture of dental appliances, surgical guides, etc.
Biocompatible nylon: Suitable for SLS printing, suitable for manufacturing surgical tools or prosthetic parts.
Biocompatible PLA filament: A common FDM printing material commonly used to make non-implantable medical devices.
When selecting a material, carefully review the biocompatibility data provided by the manufacturer and ensure that the material is suitable for your specific application scenario.
In vitro testing is a critical step in assessing biocompatibility and is usually the initial stage of a material’s biocompatibility assessment. These tests include: Cytotoxicity tests: Assess whether the material will have a toxic effect on cells. The common method is to soak the material in a medium and then culture the medium with the cells to observe the survival rate and morphological changes of the cells.
Hemolytic test: Assesses whether the material can cause red blood cells to break when it comes into contact with blood, especially for devices that require direct contact with blood, such as catheters and vascular stents.
Sensitization testing: Assessing whether a material can trigger an allergic reaction on the skin, usually by using extracts of the material on the skin of laboratory animals or human volunteers.
These in vitro tests can effectively screen out potentially harmful materials and ensure initial biocompatibility.
After in vitro testing is passed, in vivo testing is usually required to further verify the safety of the material in a real biological environment. These tests include: Subcutaneous implantation tests: Materials are implanted into the subcutaneous tissue of a laboratory animal to observe tissue reactions such as inflammation, fibrosis, or other adverse reactions. This helps assess how well the material will react in human tissue. Long-term implantation testing: For materials that need to be implanted in the human body for a long time, long-term implantation testing is conducted to observe its chronic toxicity and long-term biocompatibility. In vivo testing provides data on the safety of a material in a real biological environment and is an important step in the final assessment of biocompatibility.
For some medical devices designed to be temporarily implanted or absorbable, the degradability of the material is also a key part of the biocompatibility assessment. The degradation behavior of the material in the biological environment needs to be evaluated to ensure that the degradation products do not produce toxicity or other adverse effects on the organism.
Degradability assessment usually involves measuring the rate at which a material degrades in simulated bodily fluids or in a real biological environment to ensure that the degradation meets the expected clinical needs. Analyze the chemicals produced after the material degrades to ensure that they are non-toxic and do not trigger adverse biological reactions.
Assessing the biocompatibility of 3D printed materials is a critical step in ensuring their safe use in medical and biological applications. By understanding biocompatibility requirements, selecting suitable materials, conducting comprehensive in vitro and in vivo testing, assessing the degradability of materials, and ensuring compliance with relevant regulations and standards, you can ensure the safety and effectiveness of your selected materials in your application. This not only protects the health of the end user, but also provides a solid basis for market access of the product.