Immuno-atomic force microscopy characterization of adsorbed fibronectin

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Molecular Biophysics

Background:

• Fibronectin (Fn) conformation influences its biological activity.
• Understanding Fn's surface interactions is crucial for biomaterial design.
• Atomic force microscopy (AFM) offers high-resolution surface characterization.

Purpose of the Study:

• To characterize fibronectin (Fn) binding conformation on mica and ultraflat poly(D,L-lactide-co-glycolide) (UPLGA).
• To utilize immuno-AFM to probe Fn's binding sites upon surface adsorption.
• To correlate Fn conformation with its functional state.

Main Methods:

• Atomic force microscopy (AFM) for topographic imaging.
• Immuno-AFM using a specific antibody (Ab(hep)) to detect Fn binding sites.
• Height histogram analysis of Fn-antibody complexes to determine molecular conformation.

Main Results:

• AFM revealed Fn adopts an extended conformation on mica and a compact structure on UPLGA.
• Immuno-AFM demonstrated Fn's heparin binding site is open on mica.
• Height histograms indicated antibody binding induced a conformational change in Fn on mica.

Conclusions:

• Fibronectin conformation is surface-dependent, impacting its binding site accessibility.
• Immuno-AFM is a valuable tool for analyzing protein-surface interactions and conformational changes.
• Surface properties of biomaterials like UPLGA can significantly alter adsorbed protein structures.