Tuning polyelectrolyte multilayer structure by exploiting natural variation in fucoidan chemistry

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Fucoidan, a sulfated polysaccharide from seaweed, exhibits natural chemical variations.
• Polysaccharide-based polyelectrolyte multilayers (PEMs) are formed using polyanions and polycations.
• Understanding fucoidan's chemical diversity is key to tailoring PEM properties.

Purpose of the Study:

• To investigate how different fucoidan chemistries influence polyelectrolyte multilayer structure and properties.
• To explore the role of secondary hydrogen bonding in PEM formation using fucoidan and chitosan.
• To determine if fucoidan source can be used to fine-tune PEM film characteristics.

Main Methods:

• Formation of PEMs using fucoidan (from Fucus vesiculosus and Undaria pinnatifida) as polyanions and partially acetylated chitosan as polycations.
• Utilized ellipsometry and quartz crystal microbalance with dissipation monitoring (QCM-D) to analyze film build-up dynamics, thickness, and mass.
• Employed atomic force microscopy (AFM) for morphological analysis and X-ray photoelectron spectroscopy (XPS) for chemical characterization.

Main Results:

• Distinct morphological and structural differences were observed between PEMs formed with Fucus vesiculosus (FV) and Undaria pinnatifida (UP) fucoidans.
• UP-based PEMs exhibited thinner, denser, and less hydrated layers compared to FV-based PEMs.
• XPS confirmed altered chitosan-fucoidan interactions influenced by fucoidan type and layer number.

Conclusions:

• The chemical variations in fucoidan, specifically molecular weight and degree of acetylation, significantly impact PEM structure and properties.
• Fucoidan source can be strategically selected to fine-tune the characteristics of polysaccharide-based polyelectrolyte multilayers.
• This research provides insights into controlling PEM properties through the selection of natural polymer building blocks.