In order to spread to other host trees, the parasitic mistletoe plant has very sticky seeds that cling to bird feathers, bark, and other materials. According to a recent study, the "glue" on those seeds could inspire new biomedical adhesives.
Contained within the plant's berries, mistletoe seeds are surrounded by a mucus-like substance known as viscin. It is in turn made up of cellulose nanofibers suspended within a gelatinous matrix.
The basic idea is that when birds are eating the berries, the seeds will stick to their beak or feathers, then get transferred onto the bark of other trees. There, they'll grow into other mistletoe plants.
Assoc. Prof. Matthew Harrington, from Canada's McGill University, became curious about the potential human applications of viscin after seeing his daughter playing with a sticky mistletoe berry. Working with colleagues from Germany's Max Planck Institute of Colloids and Interfaces, he proceeded to devise a technique in which wetted viscin fibers could be formed into thin films or three-dimensional structures.
The resulting adhesive was applied to a number of different materials, then allowed to dry. As it did so, the cellulose fibers aligned with one another and bonded together. As a result, the adhesive was found to stick well to synthetic materials like metal, plastic and glass, along with biological tissues such as skin and cartilage.
That said, raising the relative humidity of the adhesive (by exposing it to water vapor) caused the fibers to swell and release their hold on one another – thus making the adhesive easy to remove from the various materials. And as an added bonus, it's both biocompatible and biodegradable.
In one experiment, a film of the viscin-based adhesive was successfully used to seal wounds cut into non-living pig skin. While that film was flexible enough to move with the skin without breaking, it could still be taken off as needed. Plans now call for more research to be conducted, to better understand what chemistry is at work within the adhesive.
The research is described in a paper that was recently published in the journal PNAS Nexus.
Source: McGill University
