What Has Been Achieved:

Raw and purified viscin from the European Mistletoe (Viscum album) was analyzed by mass spectrometry and NMR spectroscopy in regard to glycosyl composition, linkages, and molecular architecture. The analysis revealed that the plant adhesive contained two types of polysaccharides: one consisting of arabinofuranose units, linked via alpha (1,5) glycosidic linkages, having arabinofuranose side chains attached at O-2 of every fourth backbone residues (on average) and the other one consisting of galactopyranose units, linked via beta (1,6) glycosidic linkages, with side chains of one or two arabinofuranose units attached at O-3 in 2 out of 3 backbone units. The raw viscine also contained several inositol isomers and methyl derivatives, which were removable by dialysis.

Importance of the Achievement:

Although still incomplete, elucidating the chemical composition of mistletoe adhesive extract (MAE) provides the first steps toward understanding the chemical mechanisms of reversible adhesion and humidity uptake, and thus, the first steps toward mimicking this behavior. For example, the discovery of catechol-based adhesion in marine mussels has propagated enormous breakthroughs in development of underwater adhesives, while the fundamental understanding of gecko adhesion has resulted in commercialized gecko-inspired reversible tapes. Similarly, we anticipate that a deeper understanding of the adhesive chemistry of mistletoe will spark analogous breakthroughs in reversible adhesive technologies. Indeed, through systematic and thorough characterization of the various chemical components in MAE, their structure, and their function, it should be possible to directly link the adhesive prowess of MAE to specific chemical features.

Unique Feature(s) of the MIP that Enabled this Achievement:

The achievement was enabled by the preparative and analytical expertise of GlycoMIP scientists at UGA as well as the GlycoMIP-funded Orbitrap Eclipse mass spectrometry instrument.

Publication:

Stephen D. George, Elias Andraos, Tobias Priemel, Nils Horbelt, Griffin Keiser, Ambrish Kumar, Christian Heiss, Notburga Gierlinger, Parastoo Azadi, and Matthew J. Harrington. Structure, Function, and Application of Self-Healing Adhesives from Mistletoe Viscin. Advanced Functional Materials 2024, 34, 2307955. https://doi.org/10.1002/adfm.202307955

Acknowledgement statement:

The authors thank T. van de Ven for access to the mechanical tester, H. Titi of the McGill Chemistry Characterization (MC2) Facility for assistance with DVS data collection, and M. Cerruti and R. Allgayer for assistance in SEM imaging. S.D.G. acknowledges support from the FRQNT Québec Merit Award (B2X 317483). M.J.H. acknowledges funding through the Wares Scientific Innovation Prospector’s Fund and a Canada Research Chair Award (CRC Tier 2 950-231953). This study was supported in part by GlycoMIP, a National Science Foundation Materials Innovation Plat-form funded through Cooperative Agreement DMR-1933525 and the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division, under award number DE-SC0015662.