While science-fiction authors have long penned about hybrids between humans and machines, “super plants” that contain integrated nanomaterials might be much closer to science fact than cyborgs are. Today, scientists report that there are plants in development which can make nanomaterials; these are called metal-organic frameworks, or MOFs, and are applied as coatings on plants. These augmented plants might one day perform useful functions such as the sensing of chemicals or the more efficient harvesting of light.
Plants often endure blazing-hot long days to bear the vegetables and fruits their growers desire. The ultraviolet or UV rays of the sun can be intense; enough so to damage some crops. These plants might well thrive if they had a hand from some built-in sunscreen. A family of MOFs can absorb UV radiation that is harmful. Some MOFs can turn UV rays into other wavelengths, such as those that plants can utilize for photosynthesis.
A nano-engineer, Joseph Richardson, is working to lead a research team that seeks to make plants uptake the MOFs’ building blocks. Their goal is for plants to make their own MOFs. MOFs are too big to be taken up by plant roots. Cutting plants open to cram them full of nanoparticles would cause damage to the stems. So this team seeks another way. If these MOFs can capture UV rays that damage tissues, they might assist crops in surviving tougher climates still, both on Earth’s surface and out in space.
Richardson had a realization that the building blocks of MOFs are quite small; so small, in fact, that plant roots can drink them up. Now the building blocks must assemble within the plant and grow, on-site, to complete MOFs. The metal atoms and unique carbon compounds that comprise the building blocks were dissolved in water. Plant cuttings were then placed in this solution. It worked; these simple materials, absorbed by the plant, grew into fully-formed MOFs.
The scientists caused the MOFs in question to emit a green light that was intense when irradiated with the rays of UV light. This helped confirm that the plants were building MOFs. The entire plant fluoresced under the UV light. MOFs were formed in the stems, leaves, roots, and other plant parts.
Researchers are examining the protective qualities of the nanomaterials with promising preliminary data. The team tried coating clippings of lilyturf and chrysanthemum with luminescent MOFs; these were exposed to UVC light for several hours. After the three hours, compared with uncoated clippings, the MOF-ridden plants showed less bleaching and wilting.
MOF durability is a concern of C. Michael McGuirk. This materials chemist is worried that MOFs break down as time passes, losing their properties and unique structures. He mentions that this happens especially in water, which is a requirement of plant growth.
The next step is studying the MOFs’ effect on the growth of the plants they are taken up by. So far, toxicity has not been noticed in the nanomaterials. The MOFs may even someday help plants to grow better. This could lead to exciting new applications in agriculture. Hostile outposts, including space, may one day be fed by these MOF-embedded plants.