Plants' biological structures could be useful for biomaterial production

London, August 15 (ANI): Plants exhibit an enormous range of mechanical properties, depending on the arrangement of a cell wall's four main building blocks: cellulose, hemicellulose, lignin and pectin, an MIT researcher has found.

Understanding plants' microscopic organization may help engineers design new, bio-inspired materials, according to Lorna Gibson, the Matoula S. Salapatas Professor of Materials Science and Engineering at MIT who has compiled data on the microstructures of a number of different plants, from apples and potatoes to willow and spruce trees.

Like wooden beams reinforcing a house, cell walls make up the structural supports of all plants. Depending on how the cell walls are arranged, and what they are made of, a plant can be as flimsy as a reed, or as sturdy as an oak.

"If you look at engineering materials, we have lots of different types, thousands of materials that have more or less the same range of properties as plants. But here the plants are, doing it arranging just four basic constituents. So maybe there's something you can learn about the design of engineered materials," Gibson says.

To Gibson, a cell wall's components bear a close resemblance to certain manmade materials. For example, cellulose, hemicellulose and lignin can be as stiff and strong as manufactured polymers. A plant's cellular arrangement can also have engineering parallels: cells in woods, for instance, are aligned, similar to engineering honeycombs, while polyhedral cell configurations, such as those found in apples, resemble some industrial foams.

To explore plants' natural mechanics, Gibson focused on three main plant materials: woods, such as cedar and oak; parenchyma cells, which are found in fruits and root vegetables; and arborescent palm stems, such as coconut trees. She compiled data from her own and other groups' experiments and analyzed two main mechanical properties in each plant: stiffness and strength.

Among all plants, Gibson observed wide variety in both properties. Fruits and vegetables such as apples and potatoes were the least stiff, while the densest palms were 100,000 times stiffer. Likewise, apples and potatoes fell on the lower end of the strength scale, while palms were 1,000 times stronger.

It turns out the large range in stiffness and strength stems from an intricate combination of plant microstructures: the composition of the cell wall, the number of layers in the cell wall, the arrangement of cellulose fibers in those layers, and how much space the cell wall takes up.

A paper detailing Gibson's findings has been published this month in the Journal of the Royal Society Interface. (ANI)