Marine adhesive proteins: natural composite thermosets

Area of Science:

• Biomaterials science
• Marine biology
• Adhesion science

Background:

• Synthetic adhesives fail in marine environments due to water, oxides, erosion, and swelling.
• Marine organisms like barnacles and mussels exhibit robust underwater adhesion.
• Understanding marine adhesives can lead to novel, environmentally safe, water-resistant adhesives.

Purpose of the Study:

• To investigate the chemistry and bioprocessing of marine adhesives.
• To identify key components and mechanisms responsible for underwater adhesion in marine organisms.
• To inform the development of next-generation synthetic adhesives inspired by nature.

Main Methods:

• Isolation and partial sequencing of precured resins from seven marine organisms (Mollusca, Annelida, Platyhelminthes).
• Analysis of protein composition, focusing on amino acid content and conformation.
• Identification of functional groups, particularly 3,4-dihydroxyphenyl-L-alanine (DOPA), and associated enzymes like catecholoxidase.

Main Results:

• Marine adhesive resins are protein-based with basic isoelectric points.
• High concentrations of DOPA were identified, crucial for underwater surface chemisorption.
• Adhesives feature an extended, flexible conformation, with DOPA facilitating cross-linking catalyzed by catecholoxidase.

Conclusions:

• Marine adhesives function as composite thermosets with variable fibers and fillers.
• The DOPA functional group is critical for both underwater surface binding and adhesive cross-linking.
• Further research into adhesive processing and delivery strategies is needed to fully harness these natural systems.