Scientists at Nanyang Technological University, Singapore (NTU Singapore) discovered how to turn ultra-tough pollen, into a soft and flexible material.
Research findings were published in Nature Communications on 19 March 2020, they demonstrated how the team used a simple chemical process akin to conventional soap-making to turn pollen grains from sunflowers and other types of plants into soft microgel particles that respond to various stimuli.
They suggest that, coupled with advances in 3D and 4D printing, the resulting pollen-based particles might one day be turned into a range of different forms including polymer gels, sheets of 'paper' and sponges.
The corresponding authors of this paper are Assistant Professor Song Juha of the School of Chemical and Biomedical Engineering, and Professor Cho Nam-Joon and Professor Subra Suresh of the School of Materials Science and Engineering at NTU Singapore.
NTU Distinguished University Professor Subra Suresh, who is also the NTU President, said: "Our NTU research team has transformed hard pollen grains beyond their natural performance limits, and converted them into soft microgel particles that alter their properties in response to external stimuli. This holds promise for a wide range of applications that are environmentally sustainable, economically affordable, and practically scalable."
To date, the results suggest biocompatibility of pollen-based microgel particles – proving that it does not cause an immunological, allergic or toxic reaction when in contact with body tissue. This characteristic give it the potential to be suitable for applications in wound dressing, prosthetics, and implantable electronics.
Professor Cho Nam-Joon, who holds the Materials Research Society of Singapore Chair in Materials Science and Engineering, said: "Both our experimental and computational results give insight into the pollen's basic biological mechanisms, and demonstrate how altering the pollen wall structure can cause the pollen particles to swell - much like the shape transformations that occur during biological processes such as harmomegathy (the folding of the pollen grain to prevent water loss) and germination. The results also show that we can go beyond the performance limits of what nature can accomplish by itself."
Upon arrival of the pollen grains to the plant’s female reproductive part, the pollen tube will grow out of the grain. This process is controlled by enzymes within the pollen wall structure, altering the wall’s elasticity, leading to structural changes. These processes inspired the NTU team to attempt to remodel the pollen's entire wall structure and alter its material properties, using a process similar to conventional soap-making.
Computer simulations allowed the team to identify that elastic properties of the outer and inner wall layers required a precise range for pollen-derived material to exhibit its gel-like behaviour. This suggested that for a single pollen particle, there is a chemical and physical pathway determining successful germination.
Assistant Professor Song Juha shared, “our study inspires future investigation into understanding how the materials science of pollen might influence plant reproductive success."