Elastic modulus of single cellulose microfibrils from tunicate measured by atomic force microscopy

Area of Science:

• Materials Science
• Biophysics
• Nanotechnology

Background:

• Cellulose is a key biopolymer with diverse applications.
• Understanding the mechanical properties of individual cellulose microfibrils is crucial for advanced material design.
• Tunicate cellulose offers a unique source of highly crystalline nanocellulose.

Purpose of the Study:

• To determine the elastic modulus of single microfibrils from tunicate (Halocynthia papillosa) cellulose.
• To compare the mechanical properties of tunicate cellulose microfibrils prepared via different methods.
• To validate experimental findings against theoretical models of cellulose crystals.

Main Methods:

• Isolation of cellulose microfibrils using TEMPO-oxidation and sulfuric acid hydrolysis.
• Deposition of microfibrils on a grooved silicon wafer.
• Atomic Force Microscopy (AFM) with a three-point bending test to measure elastic modulus.

Main Results:

• Elastic moduli of single tunicate cellulose microfibrils were determined to be 145.2 ± 31.3 GPa (TEMPO-oxidation) and 150.7 ± 28.8 GPa (acid hydrolysis).
• The measured elastic moduli are consistent with the known elastic modulus of native cellulose crystals.
• Demonstrated the high stiffness and crystalline nature of tunicate-derived nanocellulose.

Conclusions:

• Tunicate cellulose microfibrils exhibit exceptionally high elastic modulus, comparable to native cellulose crystals.
• The preparation methods (TEMPO-oxidation and acid hydrolysis) yield nanocellulose with similar mechanical properties.
• These findings support the potential of tunicate cellulose as a high-performance biomaterial.