Interplay between β-Chitin Nanocrystal Supramolecular Architecture and Water Structuring: Insights from...

Area of Science:

• Biomaterials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Chitin is an abundant biopolymer with potential as a renewable resource.
• The structural and hydration properties of beta-chitin nanocrystals (NCs) are not fully understood.
• Understanding beta-chitin NCs' behavior in water is key to utilizing their full potential.

Purpose of the Study:

• To elucidate the surface structure and hydration properties of individual beta-chitin NCs.
• To investigate the impact of pH on the 3D supramolecular arrangement of beta-chitin NCs in aqueous environments.
• To advance the mechanistic understanding of beta-chitin NCs for renewable applications.

Main Methods:

• Atomic Force Microscopy (AFM) for in situ imaging of beta-chitin NCs.
• Molecular Dynamics (MD) simulations to complement AFM data.
• 3D-AFM to analyze heterogeneous hydration shells and hydrogen bonding networks.

Main Results:

• AFM revealed a highly ordered crystalline architecture of beta-chitin NCs with molecular detail.
• Water intercalation was observed to expand the chitin lattice along the b-axis.
• Heterogeneous, pH-dependent hydration shells form a 3D hydrogen bonding network, creating barriers to ion interaction and potentially enabling selective biomolecular interactions.
• Alpha-chitin NCs showed stronger hydration forces than beta-chitin NCs.

Conclusions:

• The study provides unprecedented molecular detail on beta-chitin NCs' surface structure and hydration.
• Findings advance the understanding of beta-chitin's interaction with water, crucial for biological processes and chitin decrystallization.
• This work enables efficient use of chitin in renewable products and guides the design of sustainable bionanomaterials.