Tapping mode Atomic Force Microscopy of scleroglucan networks

Area of Science:

• Biophysics
• Materials Science
• Polymer Chemistry

Background:

• Scleroglucan is a fungal polysaccharide with a triple helix structure.
• Understanding scleroglucan's assembly is crucial for its applications.

Purpose of the Study:

• To investigate the morphology of scleroglucan deposited from different solvents using Tapping mode Atomic Force Microscopy (TmAFM).
• To elucidate the factors influencing scleroglucan network formation and denaturation/renaturation behavior.

Main Methods:

• Scleroglucan solutions were prepared in aqueous and DMSO solvents after dissolution and neutralization.
• Samples were deposited onto mica surfaces for imaging.
• Tapping mode Atomic Force Microscopy (TmAFM) was employed for high-resolution imaging.
• Analysis included measuring triple helix diameter and fractal dimension.

Main Results:

• Aqueous scleroglucan solutions formed extended networks attributed to imperfect triple helix registration and chain stiffness.
• The measured triple helix diameter was 0.92 +/- 0.27 nm.
• DMSO-deposited scleroglucan showed web-like layers with sphere-like structures, indicative of denatured, flexible chains.
• Renaturation into rod-like structures was observed upon water addition to DMSO-deposited samples.
• Analysis of aqueous networks yielded a Flory-like exponent of 0.67 and a fractal dimension of 1.22 +/- 0.06.

Conclusions:

• Scleroglucan network formation is influenced by solvent properties and the inherent structure of its triple helix.
• TmAFM is effective in visualizing the distinct morphologies of scleroglucan under different conditions.
• The study provides insights into the conformational flexibility and assembly of scleroglucan, relevant for biomaterial design.