Protein assembly at the air-water interface studied by fluorescence microscopy

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Biophysics

Background:

• Protein assembly at the air-water interface (AWI) is crucial for biological processes and biomaterial creation.
• Understanding the factors controlling protein self-assembly and dynamics at the AWI remains an underexplored area.
• Human serum albumin serves as a model protein for studying interfacial phenomena.

Purpose of the Study:

• To investigate the factors influencing protein self-assembly at the AWI.
• To explore the dynamic processes of protein adsorption at the AWI.
• To characterize the microstructure of protein assemblies under varying conditions.

Main Methods:

• Utilized fluorescence microscopy to observe protein assembly at the AWI.
• Employed Texas Red-labeled human serum albumin as a model system.
• Applied fluorescence recovery after photobleaching (FRAP) to assess domain dynamics.

Main Results:

• Protein assembly microstructure at the AWI was modulated by solution concentration, ionic strength, and redox state.
• Pluronic surfactant addition induced phase segregation, creating distinct fluid surfactant and rigid protein domains.
• Coalescence of protein domains was observed during competitive adsorption with surfactant.

Conclusions:

• Solution conditions significantly influence protein assembly microstructure at the AWI.
• Surfactants can induce phase separation at the AWI, leading to distinct domain formation.
• Competitive adsorption dynamics between proteins and surfactants at the AWI are complex and lead to domain coalescence.