Manipulating Nanoparticle Aggregates Regulates Receptor-Ligand Binding in Macrophages

Area of Science:

• Biomaterials Science
• Cell Biology
• Nanotechnology

Background:

• Receptor-ligand interactions are crucial for cellular functions.
• Ligand accessibility dynamically regulates these interactions.
• Controlling ligand accessibility is key to modulating cell behavior.

Purpose of the Study:

• To investigate the role of "accessible ligand dispersity" in receptor-ligand binding.
• To demonstrate the use of tunable magnetic nanoparticle aggregates to control ligand accessibility.
• To explore the impact of controlled ligand accessibility on macrophage adhesion and polarization.

Main Methods:

• Utilized size-tunable magnetic nanoparticle aggregates anchored to RGD ligand-active surfaces.
• Maintained constant accessible ligand density while varying aggregate size (ligand dispersity).
• Employed magnetic manipulation to reversibly alter ligand accessibility.
• Assessed macrophage adhesion and polarization in vitro and in vivo.

Main Results:

• Increased aggregate size (lower dispersity) enhanced macrophage adhesion by facilitating integrin binding.
• Magnetic lifting of aggregates increased ligand accessibility, augmenting macrophage adhesion and pro-healing polarization.
• Magnetic dropping of aggregates decreased ligand accessibility, suppressing binding and promoting inflammatory polarization.

Conclusions:

• Introduced "accessible ligand dispersity" as a novel, fundamental parameter regulating receptor-ligand binding.
• Demonstrated reversible control over cell adhesion and polarization via magnetic manipulation of ligand accessibility.
• Highlighted the potential of tunable nanoparticle aggregates for precise control of cellular responses.