Analysis of HSA-PAA Complexation Using SEC-SAXS Combination: Unraveling Stoichiometry, Reversibility, and Interaction...

Area of Science:

• Biochemistry
• Materials Science
• Polymer Chemistry

Background:

• Human serum albumin (HSA) is a crucial protein in blood plasma.
• Understanding protein-polymer interactions is vital for drug delivery and biomaterials.
• Poly(acrylic acid) (PAA) is a synthetic polymer with tunable properties.

Purpose of the Study:

• To investigate the complex interactions between human serum albumin (HSA) and poly(acrylic acid) (PAA).
• To characterize the structural and stoichiometric properties of HSA-PAA complexes.
• To elucidate the role of electrostatic forces and pH in HSA-PAA complex formation.

Main Methods:

• Integrated size exclusion chromatography (SEC) with small-angle X-ray scattering (SAXS).
• Analyzed HSA structure and aggregation across a pH range (5-8).
• Assessed HSA interaction with polyethylene glycol (PEG) as a control.

Main Results:

• SEC-SAXS effectively removed aggregates, improving data quality for protein-polymer associations.
• HSA maintained its native structure between pH 5-8 and did not interact with neutral PEG.
• HSA-PAA complex stoichiometry was dependent on PAA size, with larger chains forming more elongated structures.
• Binding stoichiometry increased nonlinearly, indicating a balance between attractive and repulsive forces.
• HSA-PAA complexes demonstrated reversible dissociation at pH > 5 and in PAA-free media.

Conclusions:

• Electrostatic forces and charge regulation are critical for specific HSA-PAA interactions.
• PAA size significantly influences the structure and stoichiometry of HSA-PAA complexes.
• The reversible nature of HSA-PAA complexes offers potential for controlled applications.