Measurements of long-range interactions between protein-functionalized surfaces by total internal reflection...

Area of Science:

• Surface Science
• Biomaterials Science
• Biophysics

Background:

• Protein-surface interactions are vital for biomedical implants, drug delivery, and biosensors.
• Understanding these interactions is key to controlling protein behavior on surfaces.

Purpose of the Study:

• To directly measure interactions between protein-functionalized particles and surfaces.
• To investigate the influence of pH on these protein-surface interactions.

Main Methods:

• Utilized total internal reflection microscopy (TIRM) for direct interaction measurements.
• Employed micron-sized particles functionalized with concanavalin A (ConA), bovine serum albumin (BSA), and lysozyme (LYZ).
• Used a glass surface coated with soy proteins (SP) as the substrate.

Main Results:

• Protein adsorption significantly alters surface charge properties, with pH being a critical factor.
• At pH 7.5-10.0, negatively charged particles exhibited long-range double-layer repulsion from the SP surface.
• At pH 5.0, reduced repulsion led to particle adhesion via hydrophobic attraction; at pH 4.0, behavior varied based on protein type.

Conclusions:

• pH-dependent electrostatic and hydrophobic forces govern protein-surface interactions.
• Quantified nonspecific kT-scale interactions provide insights for designing protein-based biomedical applications.
• Findings enable better control over biomolecular interactions at interfaces.