Protein sorption on polymer surfaces measured by fluorescence labels

Area of Science:

• Biochemistry
• Materials Science
• Surface Chemistry

Background:

• Protein sorption studies are crucial for understanding biomaterial interactions.
• Accurate quantification of protein adsorption is essential for surface characterization.
• Traditional labeling methods can sometimes interfere with experimental measurements.

Purpose of the Study:

• To evaluate fluorescence labeling as a sensitive method for studying protein sorption.
• To identify the most suitable fluorochrome for protein sorption analysis on hydrophilic gels.
• To investigate the impact of labeling on protein aggregation and surface affinity.

Main Methods:

• Proteins were labeled using fluorescamine, fluoresceine isothiocyanate, and dansylchloride.
• Protein sorption was quantified on poly(2-hydroxyethyl methacrylate), its copolymer with methyl methacrylate, and polyethylene.
• Electrophoretic analysis was performed to assess protein aggregation and changes in electrophoretic bands.

Main Results:

• Fluorescence labeling achieved a sensitivity of approximately 10(-8) g/cm2, similar to radioactive labeling.
• Fluorescamine was found to be superior for hydrophilic gels as the free fluorochrome did not interfere with measurements.
• Protein labeling did not induce aggregation but slightly increased affinity for hydrophobic surfaces.

Conclusions:

• Fluorescence labeling, particularly with fluorescamine, is a sensitive and reliable technique for protein sorption studies.
• The choice of fluorochrome is critical for accurate measurements, especially on hydrophilic surfaces.
• Labeling minimally affects protein integrity and can subtly alter surface interaction properties.