Centrifugation-based assay for examining nanoparticle-lipid membrane binding and disruption

Area of Science:

• Nanotechnology
• Biophysics
• Materials Science

Background:

• Centrifugation assays are standard for studying protein-membrane interactions using lipid bilayer vesicles.
• Nanoparticle-membrane interactions are crucial for understanding nanoparticle behavior in biological and environmental systems.
• Surface functionalization, lipid composition, and salt concentration significantly influence these interactions.

Purpose of the Study:

• To develop and validate a centrifugation-based assay for studying nanoparticle-membrane interactions.
• To investigate the binding of different silver nanoparticle (AgNP) surface functionalizations (Ag-COOH, Ag-NH, Ag-PEG) to various membrane vesicles.
• To analyze the impact of salt concentration on AgNP aggregation and binding.

Main Methods:

• Utilized a centrifugation assay to separate bound and unbound nanoparticles.
• Employed surface plasmon resonance (SPR) to quantify AgNP binding and aggregation.
• Applied cryogenic transmission electron microscopy (cryo-TEM) for direct visualization of AgNP-membrane complexes and vesicle integrity.

Main Results:

• AgNP binding and vesicle disruption were strongly correlated with electrostatic attraction between nanoparticles and membranes.
• Ag-PEG nanoparticles, despite a neutral coating, demonstrated binding to anionic membranes, with aggregation increasing at higher salt concentrations.
• The assay successfully differentiated binding affinities based on nanoparticle surface chemistry and membrane composition.

Conclusions:

• The developed centrifugation assay offers a rapid and reliable method for screening nanoparticle-membrane interactions.
• Electrostatic forces play a dominant role in governing AgNP binding and subsequent effects on membrane vesicles.
• Understanding these interactions is vital for designing nanoparticles with specific biological or environmental applications.