Adhesion forces between protein layers studied by means of atomic force microscopy

Area of Science:

• Biophysics
• Surface Science
• Materials Science

Background:

• Understanding protein-substrate interactions is crucial in biomaterials and surface chemistry.
• Adsorption of proteins onto surfaces alters surface properties and biological interactions.
• Quantifying adhesion forces provides insights into interfacial phenomena.

Purpose of the Study:

• To measure adhesion forces between protein layers on different substrates.
• To investigate the influence of environmental factors on protein adhesion.
• To elucidate the role of electrostatic interactions in protein layer adhesion.

Main Methods:

• Atomic Force Microscopy (AFM) with the colloid probe technique was employed.
• Experiments were conducted in aqueous media with varying salt concentrations and pH.
• Two distinct proteins (bovine serum albumin, apoferritin) and substrates (silica, polystyrene) were utilized.

Main Results:

• Adhesion forces, pull-off distance, and separation energy were quantified.
• Loading force, salt concentration, pH, and electrolyte type were found to affect adhesion.
• Electrostatic interactions were identified as a major contributor to adhesion between protein layers.

Conclusions:

• Protein layer adhesion is strongly influenced by electrostatic forces.
• Environmental conditions significantly modulate the adhesion characteristics of protein layers.
• AFM colloid probe technique is effective for studying protein-surface interactions.