Today, many associate mistletoe with holiday kisses. But for centuries, the plant was known for its amazing stickiness. The ancient Greeks and Romans used the sticky mistletoe berries for a variety of uses, from bird traps to ointments for skin ulcers. Biochemists are currently investigating whether mistletoe’s stickiness can provide a natural alternative to synthetic adhesives.
Stickiness is essential for mistletoe parasitic plants. Inside each berry are seeds that are coated with a slimy substance called bistin. After the bird devours and digests the berry, it releases a clump of seeds with strands of this substance that hang down the branches of the tree and glue the seeds in place. is absorbed and embedded in the tree.
To find out why this natural glue is sticky, chemical biologist Matt Harrington of McGill University and researchers at the Max Planck Institute for Colloidal Interfaces in Potsdam have grown on apple trees in Germany. Using tweezers, the filamentous bistines were pulled from the berries and examined closely.
In a study published in PNAS Nexus, the team found that Bistine’s structure sets it apart from other adhesives. While many synthetic adhesives start out as sticky puddle of chemicals, Bistine is made up of stiff strands of cellulose that help hold it in place. Encased in a moisture-sensitive coating that preserves Under humid conditions, bistine threads about half a centimeter long can stretch to more than two meters. “This multifunctional, humidity-sensitive nature blew my mind,” says Harrington.
Researchers have found that bistine is strong and can support 50 times the weight of mistletoe seeds. Viscin is adapted to stick to bark and feathers, but the researchers found it sticks to everything, including skin. (Wetting your Vistin-covered hands won’t remove the compound, but rubbing them together will create enough heat and moisture to loosen your grip, Harrington says.)
Scientists say viscin can be used as a biodegradable agent to seal fresh wounds. They tested Bistine on pork cuts from a local butcher. Once the bistine dried, it kept the gouache hermetically sealed, even when force was applied.
According to Juliann Aukema, a USDA Forest Service researcher who studies mistletoe ecology and was not involved in the study, this alternative to petroleum-based synthetic adhesives highlights the ancient importance of mistletoe. may be revived. “There is this wealth of knowledge about mistletoe that we had and lost,” he says Aukema. “And we’re relearning it in 2022.”
