What is Bioprinting? Types, Applications

Bio-imprinted materials can be used to repair damaged organs. A type of 3D printing, bioprinter uses cells and other biological materials as ink to produce 3D biological structures. Bio-imprinted materials have the potential to repair damaged organs, cells, and tissues in the human body. In the future, bioprinting can be used to build whole organs from scratch; this could transform the bioprinting space.

Bioprintable Materials

Researchers have studied the bio pressure of many different cell types, including stem cells, muscle cells, and endothelial cells. Several factors determine whether a material can be bio-printed or not. First, biological materials must be biocompatible with the materials in the ink and the printer itself. In addition to the mechanical properties of the imprinted structure, the time is taken for the organ or tissue to mature also affects the process.

Bio links generally fall into one of two types:

• Water-based gels or hydrogels function as 3D structures from which cells can grow. Hydrogels containing cells are printed in defined ways. And the polymers in hydrogels are combined or cross-linked so that the printed gel becomes stronger. These polymers can be derived naturally or synthetically but must be compatible with cells.

• After printing, self-fusing cell clusters are created in the tissues.

How Does Bioprinting Work?

The biological printing process has many similarities to the 3D printing process. Bioprinting is usually divided into the following steps:

• Pre-processing: A 3D model is prepared based on the digital reconstruction of the organ or tissue to be biologically printed. This reconstruction can be created based on images captured non-invasively (eg with an MRI) or through a more invasive process, such as a series of two-dimensional slices imaged with X-rays.

• Processing: In the preprocessing stage, tissue or organ based on the 3D model is printed. As with other 3D printing varieties, layers of material are added on the back to print the material.

• Post-Procedure: Necessary procedures are applied to turn the print into a functional tissue or organ. These procedures involve placing the print in a special chamber that will help the cells mature faster and more accurately.

SEE ALSO: How to Make an Artificial Cell?

Biological Printer Types

As with other types of 3D printing, bio links can be printed in several different ways. Each method has its own advantages and disadvantages.

• Inkjet bioprinting: Works similar to an office inkjet printer. When a design is printed with an inkjet printer, ink is sprayed onto the paper through many small nozzles. This creates an image consisting of many droplets that are too small to be seen with the eye. The researchers have adapted inkjet printing for bioprinting, including methods that use heat or vibration to pass ink through nozzles. These bioprinters are more economical than other techniques but are limited to low-viscosity biostructures, which can limit the types of materials that can be printed.

• Laser-assisted bioprinter: Uses a laser to move cells from a solution to a surface with high precision. The laser heats a portion of the solution and then creates an air pocket, thereby shifting the cells towards a surface. Because this technique does not require small nozzles as is the case with inkjet bioprinting, higher viscosity materials can be used that cannot easily flow through the nozzles. The laser-assisted bioprinter also allows for very high precision printing. However, the heat from the laser can damage the cells being printed. Moreover, the technique cannot be easily scaled to quickly print large quantities of builds.

• Extrusion-based bioprinter: Uses pressure to push material out of a nozzle to create stable shapes. This method is relatively versatile. Biomaterials with different viscosities can be printed by adjusting the pressure, but care must be taken as higher pressures are more likely to damage the cells. Extrusion-based bioprinting is likely to scale for production, but may not be as precise as other techniques.

• Electrospray and electrospinning bioprinters: Utilize electric fields to form droplets or fibers respectively. These methods can have nanometer precision. However, they use very high voltage that can be dangerous for cells.

Bioprinting Applications

Because biological printing allows biological structures to be constructed with precision, the technique can find many uses in biomedicine. Researchers have used bio pressure to introduce cells to help repair the heart after a heart attack, as well as to store cells in injured skin or cartilage. Bioprinting has been used to produce heart valves for possible use in patients with heart disease, build muscle and bone tissue, and help repair nerves. Although more studies are needed to determine how the results obtained will perform in a clinical setting, research shows that bioprinting can be used by providing tissue regeneration during surgery or after injury. In the future, biological printers can also enable all organs such as the liver or heart to be made from scratch and used in organ transplants.

4D Biological Printing

In addition to 3D bioprinting, some groups have also studied 4D bioprinting, which also takes into account the fourth dimension of time. 4D bioprinting is based on the idea that printed 3D structures can continue to evolve over time, even after printing. Structures can change their shape and/or function when exposed to the right stimulus such as heat. 4D bioprinting can find use in biomedical fields such as making blood vessels by taking advantage of how certain biological structures fold and roll.

Bio-printing in the future

While biological pressure can help save many lives in the future, a number of challenges still need to be overcome. For example, after the imprinted structures are transferred to the appropriate place in the body, they may be weak and not keep their shape. Moreover, tissues and organs are complex and contain many different types of cells arranged in very precise ways. Current printing technologies may not be able to replicate such complex architectures. Finally, current techniques are also limited to certain types of materials, a limited viscosity range, and limited precision. Each technique has the potential to damage cells and other printed materials. These issues will be addressed as researchers continue to develop bioprinting to address increasingly difficult medical and engineering problems.

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References: https://www.science.org.au/curious/people-medicine/bioprinting