Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

Area of Science:

• Polymer Science
• Surface Chemistry
• Biophysics

Background:

• Single molecule force spectroscopy using atomic force microscopy (AFM) is vital for studying polymer-surface interactions.
• Covalent attachment and surface passivation are essential for accurate single molecule experiments, preventing artifacts.

Purpose of the Study:

• To develop and validate a reliable functionalization protocol for single polymer-surface interaction studies using AFM.
• To enable precise characterization of polymer stretching and desorption behavior at the single molecule level.

Main Methods:

• Utilized AFM-based single molecule force spectroscopy.
• Developed a robust functionalization protocol for covalent attachment of probe polymers.
• Implemented surface passivation techniques to minimize non-specific binding.
• Analyzed force-extension traces to extract physical parameters.

Main Results:

• Demonstrated a reliable protocol applicable to various polymers like PEG, PNiPAM, and PS.
• Successfully obtained characteristic single molecule events (stretches, plateaus) in force-extension traces.
• Quantified physical parameters including stretching force, desorption force, and desorption length.

Conclusions:

• The presented functionalization protocol is effective for precise single molecule investigation of polymer-surface interactions.
• This method is particularly valuable for studying stimuli-responsive polymer systems.
• The protocol facilitates detailed analysis of polymer behavior under force in aqueous environments.