Wrapping nano- and microgels at lipid-bilayer membranes

The interaction of nano- and microparticles with lipid membranes plays a key role in the process of cellular engulfment.¹ The physico-chemical parameters that control engulfment are size, shape and elasticity of the particle, bending rigidity and tension of the membrane, and particle-membrane adhesion strength. Polymeric gels are particularly versatile because their elasticity can be tuned in a wide range by changing the density of crosslinkers.² Using spring networks for the microgels and triangulated surfaces for the membranes, we study microgel wrapping at lipid bilayers.³ Hertz theory is employed to characterize the microgel’s Young’s modulus and Poisson’s ratio. We then determine the interplay of microgel and membrane deformations upon microgel wrapping. Our numerical simulations predict an increased stability of partial-wrapped states for microgels with lower Young’s moduli. There is a discontinuous transition from oblate to nearly spherical microgels with increasing wrapping fractions, irrespective of membrane tension. Volume and surface area of partial-wrapped microgels are significantly reduced compared with those of free microgels.³ Understanding nano- and microgel wrapping will facilitate the design of tunable and responsive polymeric gels for biomedical applications, e.g., targeted drug delivery vectors.