Tuneable Adsorption of Soft Colloids on Model Biomembranes

We investigate the interactions of responsive microgel particles with lipid biomembranes. These particles feature a rapid volume phase transition close to human body temperature and have the ability to adapt both their conformation and interaction potential to the local environment. Spherical PNIPAM microgels are acting as switchable stabilizers for giant unilamellar vesicles (GUVs).¹ These particles can be used to increase and control the stability of lipid vesicles where their softness and deformability play a major role. At 20°C, the swollen and hydrophilic microgels adsorb evenly and densely pack in 2D hexagonal arrays at the DOPC GUV surfaces, whereas above their volume phase transition temperature (T_VPT=32°C), the collapsed and more hydrophobic particles partially desorbed and self-organize into domains at the GUV/GUV interfaces. Furthermore, the shape anisotropy and initial orientation of the particles are crucial to the interactions between the particle and the lipid bilayer, where the penetrating capability of a nanoparticle is influenced by the contact area with the membrane and the local curvature of the particle at the contact point.² Unlike spherical microgels, core-shell ellipsoidal PNIPMAM-PS composite microgel not only facilitate a higher adhesion due to the large surface contact area on the GUV surface, but at their volume phase transition (45°C) can facilitate penetration across the lipid bilayer that is determined by a larger local curvature of the particle at the contact point.