Sweet bioengineering
New 3D Printer Prints Sugar Base for Artificial Organs
Yulia Vorobyova, Vesti
Engineers at the University of Illinois have developed a new printer for three-dimensional printing, which creates truly sweet objects, though not intended for consumption.
We are talking about water-soluble biodegradable structures that are printed, unlike conventional three-dimensional objects, not in layers, but are formed into the thinnest network of "threads" of isomaltite. This material is synthesized from sucrose and is colorless, sweet-tasting crystals.
Let us explain that in nature isomaltite is found in sugar cane, beetroot and honey. Its crystals are widely used in the food industry to give products volume, provide the right structure and medium sweetness. The production of ice cream, chocolate, caramel, grilling and other delicacies today is not complete without isomaltite.
However, this compound has other applications. Isomaltite crystals can be successfully used in biomedical engineering.
In particular, a team of American researchers suggests creating scaffolds ("scaffolding") from such material, which will become the basis for bioengineering objects.
The main advantage of the material is that it is not only durable, but also easily soluble. For example, on an isomaltite matrix, a heart, liver or other organ can be formed from tissues and cells, and then it can be dissolved without a trace. The resulting fabrics will already be able to keep their shape by that time.
Professor of bioengineering and one of the leading authors of the work Rohit Bhargava notes that the new technology also opens up unique opportunities for the study of malignant tumors. When cancer cell cultures are grown in the laboratory, the tissues turn out to be flat, and this makes it difficult to study some characteristics. Now, specialists will have the opportunity to look at an artificially created three-dimensional tumor and understand how it actually develops in the human body, what form it takes and how it functions. The last two indicators are closely related, the professor explains.
His team applied the mechanics of free-form printing. As the printer nozzle moves in space, the molten material solidifies, forming a solid structure. And the main thing is that it can be absolutely any shape.
Scientists have considered other types of "sugar" printing, but it turned out that only isomaltite meets all the requirements. In other cases, there were problems with either crystallization or dissolution of materials, says Matthew Gelber, another lead author of the study.
To work with the sweet compound, the team designed a special 3D printer with the necessary technological and mechanical characteristics. In particular, it was necessary to calibrate the nozzle diameter, the printing speed, and also to clearly adjust the temperature and pressure indicators.
Next, specialists from Wolfram Research, which is engaged in the production of mathematical software, joined the work.
"You have a design of what you want to get, but how do you tell the printer to do it? How do you determine the sequence of printing all these intersecting threads so that it (the construction – ed.) does not collapse?", – says Gelber.
Therefore, the next stage of the work was the creation of an algorithm for the design of final structures and the selection of printing parameters.
As a result, the team received a printer that is able to create free-form structures from thin threads-rods with round cross-sections.
When the isomaltite dissolves, a ready-made organ remains, penetrated by a network of "tunnels" that can take on the role of blood vessels for transporting nutrients to tissues or the role of channels in microfluidic systems (for example, "organs-on-a-chip").
It is also important that the technology allows you to control the mechanical properties of each of the parts of the overall structure. To do this, you need to make the appropriate changes to the print settings.
"For example, we printed a rabbit. In principle, we could change the mechanical properties of its tail so that it differs from the back or from the ears. This is very important biologically," explains Bhargava. When using classical polymer printing, it is impossible to achieve such an effect: the parameters of the application of the material and the mechanical properties of the final object are very difficult to change, the scientist continues.
Now his team is studying the microfluidic properties of the systems and conducting tests with cell cultures to understand how quickly sugar scaffolds can dissolve.
In addition, the researchers also plan to develop special coatings similar to pill shells that will help control the process of dissolution of structures.
The technology of creating a prototype 3D printer for working with isomaltite is described in detail in an article published in the publication Additive Manufacturing (Gelber et al., Model-guided design and characterization of a high-precision 3D printing process for carbonate glass). The engineers hope that their work will be useful to other researchers for the production of a new generation of printers and the study of various applications of "sweet" printing.
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