Elastic Properties of Polymer-Decorated Membranes

Membrane curvature induced by polymers and colloids

“…If the coverage of the membrane by anchored polymers is larger than the overlap coverage. one enters the brush regime [5,18,19]. The properties of such a brush depend on the reduced coverage l= = (a,,,,&,,,)2, where i;llll is the mean anchor separation (which is taken to be curvature independent here).…”

Flexible membranes with anchored polymers

“…A small curvature expansion up to second order in the curvatures leads to the effective bending rigidity and to the effective Gaussian bending modulus where the dimensionless coefficient is positive whereas is negative [6]. For ideal polymers, one finds and .…”

“…It is then convenient to introduce the reduced coverage defined by which is essentially the area fraction of the monolayer surface covered by anchors. The corresponding overlap coverage is If the brush is again anchored on one side of the membrane, the membrane bends away from the brush and exhibits a polymer-induced curvature which increases monotonically with the coverage For good solvent conditions, scaling arguments based on the blob picture [24][25][26] lead to and for small and large respectively [6], where the Flory value has been used. As in the case of mushrooms, the polymer brush acts to increase the bending rigidity , but to decrease the Gaussian bending modulus .…”

“…In this paper, I review our recent work on such systems [5][6][7][8]. The polymers are attached to the membranes by anchor segments which insert into the membranes.…”

“…The same mechanism is effective for biopolymers and biomembranes [9,10]. Two general aspects related to the flexibility of these objects will be emphasized: (i) anchored polymers induce a spontaneous curvature of the membranes [5][6][7], and (ii) the adhesion of membranes mediated by sticky polymers exhibits a threshold behavior arising from the membrane fluctuations [8].…”