Robust, universal, and persistent bud secretion adhesion in horse-chestnut trees.

Area of Science:

• Biomaterials Science
• Adhesion Science
• Plant Biology

Background:

• Horse-chestnut tree buds secrete a viscous fluid for protection.
• The secretion's resilience to environmental factors and its adhesive properties are not fully understood.

Purpose of the Study:

• To investigate the physical and chemical properties of horse-chestnut bud secretion.
• To determine the secretion's adhesive capabilities and stability under various conditions.
• To explore its potential as a biomimetic adhesive.

Main Methods:

• Microscopic analysis of the secretion under heat, frost, UV radiation, and arid/wet conditions.
• Measurement of pull-off forces on hydrophilic and lipophilic surfaces.
• Spectroscopic analysis (Raman, infrared, nuclear magnetic resonance) to determine chemical composition.

Main Results:

• The secretion remains stable, non-drying, and non-melting under extreme conditions (heat, frost, UV, arid).
• It exhibits universal wetting and adhesion to diverse surfaces, with high pull-off forces (up to 204 kPa).
• Spectroscopic analysis revealed a composition of aliphatic hydrocarbons, esters, carboxylic acids, amides, and terpenoids.

Conclusions:

• Horse-chestnut bud secretion is a robust, multifunctional pressure-sensitive adhesive with potential biomimetic applications.
• Its unique composition, including nonpolar and polar components, enables universal adhesion and stability.
• Findings offer insights into ecological-adhesion mechanisms and inspire novel adhesive designs.