Attraction between negatively charged surfaces mediated by spherical counterions with quadrupolar charge distribution
Jasna Urbanija1, Klemen Bohinc, Alfredo Bellen
1Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia.
The Journal of Chemical Physics
|December 3, 2008
Summary
Monoclonal antibodies can cause like-charged phospholipid vesicles to merge by acting as charged counterions. This antibody-mediated coalescence is driven by the orientational ordering of charges within the antibody.
Area of Science:
- Biophysics
- Physical Chemistry
- Materials Science
Background:
- Giant unilamellar vesicles (GUVs) are model cell membranes.
- Monoclonal antibodies (mAbs) are crucial in biological and therapeutic applications.
- Interactions between charged surfaces are fundamental in colloid science.
Purpose of the Study:
- To investigate the mechanism of monoclonal antibody-mediated coalescence of negatively charged GUVs.
- To model the interaction between charged vesicles and antibodies using theoretical and simulation approaches.
Main Methods:
- Mean-field density functional theory.
- Monte Carlo simulations.
- Free energy minimization to determine equilibrium configurations.
Main Results:
- Monoclonal antibodies induced coalescence of negatively charged GUVs.
- The interaction was modeled as two interacting flat electrical double layers with antibodies as finite-sized counterions.
- Attractive interaction between like-charged surfaces was observed at high charge densities and large antibody charge separation, driven by counterion ordering.
- Interaction becomes repulsive as the charge separation within the antibody decreases.
Conclusions:
- Antibody-mediated vesicle coalescence can occur due to specific counterion properties.
- The orientational ordering of charges within antibodies plays a key role in mediating interactions between like-charged surfaces.
- This study provides insights into the physical mechanisms governing molecular interactions at charged interfaces.
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