Single molecule atomic force microscopy and force spectroscopy of chitosan

Area of Science:

• Materials Science
• Polymer Science
• Surface Chemistry

Background:

• Chitosan is a versatile biopolymer with significant potential in biomaterial applications.
• Understanding the interaction of chitosan with various surfaces at the molecular level is crucial for optimizing its use.
• Atomic force microscopy (AFM) offers a powerful tool for probing single-molecule interactions.

Purpose of the Study:

• To investigate the desorption behavior of individual chitosan polymer chains from surfaces with different chemical compositions.
• To quantify the interaction forces between chitosan and substrates using AFM-based force spectroscopy.
• To provide fundamental insights into chitosan-substrate interactions for biomaterial design.

Main Methods:

• Utilized Atomic Force Microscopy (AFM) to image chitosan adsorbed on mica.
• Employed AFM-based force spectroscopy to measure desorption energies of single chitosan chains.
• Tested interactions on various substrates: glass, self-assembled monolayers (SAMs), and polytetrafluoroethylene (PTFE).

Main Results:

• AFM imaging showed chitosan chains adopting elongated or aggregated states depending on substrate interactions.
• Desorption energies were quantified for chitosan interacting with glass (2.0±0.3×10⁻²⁰ J), SAMs (1.8±0.3×10⁻²⁰ J), and PTFE (3.5±0.3×10⁻²⁰ J).
• Results indicate varying stabilizing interactions between chitosan and the tested surfaces.

Conclusions:

• Single-molecule force spectroscopy provides valuable data on chitosan-surface interactions.
• The quantified desorption energies offer a basis for selecting appropriate substrates for chitosan-based biomaterials.
• This research contributes to the rational design and application of chitosan in biomedical fields.