May 26, 2022 (Nanowerk News) Every year, the world loses about 10 million hectares of forest, an area the size of Iceland, due to deforestation. At this rate, some scientists predict that the world’s forests could disappear in 100 or 200 years. In an effort to provide an environmentally friendly, low-waste alternative, MIT researchers have pioneered an adjustable technique for generating wood-like plant material in a laboratory that could allow someone to “grow” a product. wooden like a table without having to. cutting down trees, processing wood, etc. These researchers have now shown that by adjusting certain chemicals used during the growth process, they can accurately control the physical and mechanical properties of the resulting plant material, such as its stiffness and density. They also show that, using 3D bio-printing techniques, they can grow plant material in shapes, sizes and shapes that are not found in nature and that cannot be easily produced with traditional agricultural methods. In an effort to provide an environmentally friendly, low-waste alternative, MIT researchers have pioneered an adjustable technique for generating wood-like plant material in a laboratory. (Image courtesy of researchers) “The idea is that you can grow these plant materials exactly the way you need them, so you don’t need to do any subtractive manufacturing after the fact, which reduces the amount of energy and waste. There is a lot of potential for it to expand and grow three-dimensional structures, ”says lead author Ashley Beckwith, a recent doctor. Although still in its infancy, this research shows that plant-grown plant materials can be adjusted to have specific characteristics, which could one day allow researchers to grow wood products with the exact characteristics needed for a particular application. such as high strength to support the walls. of a house or certain thermal properties to heat a room more efficiently, explains lead author Luis Fernando Velásquez-García, chief scientist at MIT’s Microsystems Technology Laboratories. He joins Beckwith and Velasquez-Garcia in the role of Jeffrey Borenstein, a biomedical engineer and leader of the Charles Stark Draper Laboratory group. The research is published in Materials Today (“Physical, Mechanical, and Microstructural Characterization of New, 3D-Printable, Adjustable, Laboratory-Grown Plant Materials Generated from Zinnia Elegans Cell Cultures”).
Planting cells
To begin the process of growing plant material in the laboratory, the researchers first isolated the cells from the leaves of the young plants of Zinnia elegans. The cells are cultured in liquid medium for two days, then transferred to an ice-based medium, which contains nutrients and two different hormones. Adjusting hormone levels at this stage of the process allows researchers to adjust the physical and mechanical properties of plant cells that grow in this nutrient-rich broth. “In the human body, there are hormones that determine how cells develop and how certain traits arise. Similarly, by changing the concentrations of hormones in the nutrient broth, plant cells respond differently. Just by manipulating these tiny amounts of chemicals, we can bring about quite dramatic changes in terms of physical results, ”says Beckwith. Somehow, these growing plant cells behave almost like stem cells; researchers can give them clues as to what they need to become, Velásquez-García adds. They use a 3D printer to extrude the cell culture gel solution into a specific structure on a Petri dish and let it incubate in the dark for three months. Even with this incubation period, the researchers’ process is about two orders of magnitude faster than the time it takes for a tree to grow to maturity, says Velásquez-García. After incubation, the resulting cell-based material is dehydrated and then the researchers evaluate its properties.
Wood-like characteristics
They found that lower hormone levels produced plant materials with more rounded, open cells that have a lower density, while higher hormone levels caused plant materials to grow with smaller, denser cell structures. Higher hormone levels also yielded more rigid plant material; the researchers were able to grow plant material with a storage modulus (rigidity) similar to that of some natural woods. Another aim of this work is to study what is known as lignification in these plant-grown plant materials. Lignin is a polymer that is deposited on the cell walls of plants that makes them rigid and woody. They found that higher levels of hormones in the growth medium cause more lignification, which would result in plant material with more wood-like properties. The researchers also showed that, through a 3D bio-printing process, plant material can be grown in a custom shape and size. Instead of using a mold, the process involves the use of a customizable computer-aided design file that feeds on a 3D bioprinter, which deposits the cell gel culture in a specific form. For example, they were able to grow plant material in the form of a small evergreen tree. Research like this is relatively new, says Borenstein. “This work demonstrates the power that technology at the interface between engineering and biology can bring to an environmental challenge, leveraging the advances originally developed for healthcare applications,” he adds. Researchers also show that cell cultures can survive and continue to grow for months after printing, and that the use of thicker gel to produce thicker plant material structures does not affect the survival rate of cells. · Cells grown in the laboratory.
“Customizable”
“I think the real opportunity here is to be optimal with what you use and how you use it. If you want to create an object that serves a purpose, there are mechanical expectations to consider. This process is really susceptible to customization.” , says Velásquez-García. Now that they have demonstrated the effective tuning of this technique, researchers want to continue experimenting so that they can better understand and control cell development. They also want to explore how other chemical and genetic factors can drive cell growth. They hope to assess how their method could be transferred to a new species. Zinnia plants do not produce wood, but if this method is used to make a commercially important tree species, such as pine, the process should be adapted to that species, says Velásquez-García. Ultimately, he hopes this work can help motivate other groups to immerse themselves in this area of research to help reduce deforestation. “Trees and forests are an amazing tool to help us manage climate change, so being as strategic as we can with these resources will be a social necessity in the future,” Beckwith adds.