“I had never seen mistletoe before living in Germany,” says senior author Associate Professor Matthew Harrington, of McGill University, Canada. “So, when my daughter was playing with a berry from a mistletoe we bought from a local Christmas market, and it started sticking to everything, I was intrigued.”
Mistletoe are parasitic plants of Order Santalales, with a global distribution of 1,500 species, that spread via their sticky seeds. Birds will eat the berries (drupes), then poop out the seeds that stick onto anything they touch – wood, feathers, fur – but preferably another tree host that the mistletoe can parasitise. What makes the mistletoe seed so sticky is viscin, a natural cellulose adhesive.
The researchers were able to process wet viscin fibres of the European mistletoe (Viscum album) and stretch them into thin films or 3D shapes. Each mistletoe berry could produce up to two metres of this superglue thread. They showed that it adhered to synthetic materials including metals, plastics and glass, as well as biological tissues, such as skin and cartilage. In particular, the ability to stick to skin makes mistletoe glue a compelling candidate for a wound sealant or skin covering (nature’s Band-Aid?).
“I wore a thin film of viscin on my skin for three days to observe its adhesive qualities, and was able to remove it from my fingers afterwards by simply rubbing them together,” says first author Dr Nils Horbelt, from the Max Planck Institute, Germany. “But there still remain many questions about this very unusual material.”
Though these flexible viscin fibres can stick to a variety of materials, the adhesive can also be fully released under humid conditions.
Given the abundance of diversity and abundance of mistletoe plants, their potential for biomedical and mechanical applications, and the fact they are biodegradable and biorenewable, show that this plant has many more uses than just for smooching beneath during Christmas.