Researchers at Massachusetts Institute of Technology (MIT) have shown they can control the properties of lab-grown plant material, which could enable the production of wood products with little waste.
Every year deforestation leads to the loss of somewhere in the region of 10 million hectares of the world’s forests. If this continues, scientists estimate our planet’s forests could disappear entirely over the next two centuries.
Because timber plays such an important role in its use for a variety of different purposes and is often used as an environmentally friendly alternative to other products, MIT researchers have pioneered efforts to create a technique capable of creating laboratory-grown, wood-like plant material. The team has achieved this by adjusting chemicals used during the growth process to control the physical and mechanical properties of the resulting material, including the likes of stiffness and density.
Over and above this, the scientists can utilise 3D bioprinting techniques to grow the plant material in shapes and sizes not found in the natural environment, thus minimising production inputs and waste.
“The idea is that you can grow these plant materials in exactly the shape that you need, so you don’t need to do any subtractive manufacturing after the fact, which reduces the amount of energy and waste,” lead author of the research paper and recent PhD graduate Ashley Beckwith said.
“There is a lot of potential to expand this and grow three-dimensional structures,” she said.
While still in the early stages, the researchers have successfully demonstrated that plant materials grown in the lab using this technique can be tuned to have specific properties, meaning the potential to ‘grow’ wood products such as tables, doors and beams with the specific characteristics required for a particular application.
This approach could further aid the use of timber in efforts to combat climate change, such as creating wood fortified with extra strength for use in the construction of buildings, or with the necessary thermal properties to heat rooms more efficiently.
To grow the plant material in a laboratory, the technique involves isolating cells from the leaves of young Zinnia elegans plants. These cells are then cultured in liquid medium for two days, before being transferred into a gel-based medium, containing a specific mix of nutrients and hormones, which can be adjusted in order to tune the properties of the resulting plant cells.
“By changing the hormone concentrations in the nutrient broth, the plant cells respond differently. Just by manipulating these tiny chemical quantities, we can elicit pretty dramatic changes in terms of the physical outcomes,” Dr Beckwith said.
Next, the cell culture gel solution created is expelled into a petri dish, where it is left to incubate in the dark for three months. Encouragingly, this process is around twice as fast as the time it takes for a tree to naturally grow to maturity.
Once the incubation process has been completed, the material is dehydrated and its properties evaluated.
The researchers observed that lower hormone levels resulted in plant materials with more rounded, open cells with lower density, while higher hormone levels resulted in stiffer materials with smaller, denser cell structures, similar in stiffness to some naturally grown timber species.
The team also studied the ‘lignification’ of the materials. Lignin is the polymer found in the cell walls of plants that is responsible for making them rigid and woody. Higher hormone levels were found to generate more lignification, meaning the resultant plant material had more wood-like properties.
“This work demonstrates the power that a technology at the interface between engineering and biology can bring to bear on an environmental challenge, leveraging advances originally developed for health care applications,” said Jeffrey Borenstein, a biomedical engineer and group leader at the Charles Stark Draper Laboratory, who was also involved with this research.
“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 is going to serve some purpose, there are mechanical expectations to consider. This process is really amenable to customisation,” said senior author Luis Fernando Velásquez-García, a principal scientist in MIT’s Microsystems Technology Laboratories.
The research team hopes to evaluate how their technique could be applied to different species. While Zinnia elegans doesn’t produce wood, there is potential to tailor the process to widely commercially used tree species such as pine.
“Trees and forests are an amazing tool for helping us manage climate change, so being as strategic as we can be with these resources will be a societal necessity going forward,” Dr Beckwith said.
Source: MIT News
