1. Kinetics of Membrane Adhesion Mediated by Ligand–Receptor Interaction Studied with a Biomimetic System 
Alexei Boulbitch, Zeno Guttenberg, Erich Sackmann 
Biophysical Journal 
Volume 81, Issue 5, Pages (November 2001)
DOI: /S (01)
Copyright © 2001 The Biophysical Society Terms and Conditions

2. Figure 1
(a) Membrane at the substrate with two co-existing adhesion regions. i, The PEG lipo-polymers forming mushrooms model the mechanical effect of the cellular glycocalix; ii, the RGD ligands; iii, the receptors represented by protein integrin lying over the substrate; j, the area of the strong adhesion driven by the ligand–receptor interaction; jj, the region of the weak adhesion characterizing by the manifested height fluctuations; jjj, the volume enclosed between the membrane and the substrate. The water and PEG polymers contained in this volume take part in the energy dissipation during motion of the front of the strong adhesion. (b) Typical profile of the adhered membrane across the front in the region of the transition from the strongly to the weakly adhered state reconstructed by RICM.
Biophysical Journal  , DOI: ( /S (01) )
Copyright © 2001 The Biophysical Society Terms and Conditions

3. Figure 2
Adhesion area of a vesicle on the substrate. (a) The vesicle in the weakly adhered state. White and black rings represent the interference picture. (b) Nucleation of the state of the strong adhesion (arrow). (c, d) Different stages of the expansion of the strongly adhered state.
Biophysical Journal  , DOI: ( /S (01) )
Copyright © 2001 The Biophysical Society Terms and Conditions

4. Figure 3
Displacement of the front of the tight adhesion versus time for different concentrations of ligands at 1mol% PEG-lipid. The motion of the front was determined by measuring the area of tightly adhered plaque by the image processing. Assuming nearly circular area of the plaque, the front displacement can be calculated as ξ(t)={A(t)/π}1/2. For high RGD concentrations, the displacement increases linearly ξ∼t almost up to the end of the adhesion zone (a, b). For the lower ligand concentrations, (d, e), the front displacement exhibits a square-root regime ξ∼t1/2. (c) The cross-over state between the two regimes.
Biophysical Journal  , DOI: ( /S (01) )
Copyright © 2001 The Biophysical Society Terms and Conditions

5. Figure 4
(a) The square root regime constant α as the function of RGD concentration obtained by fitting the displacement curves (c, d, e) shown in Fig. 3. The black circle represents α obtained using the data reported in Park et al. (1990). The dashed line shows the linear fit. (b) The front displacement versus the PEG concentration in the regime of the steady motion (corresponding to that shown in Fig. 3 a) at 2mol% RGD. The solid line shows the exponential fit. (c) The displacement (a–c) shown in Fig. 3 where fitted with a linear function. The slopes were plotted against the RGD-lipid concentration. For the high RGD contents (a, b) the speed is nearly independent of the ligand concentration as expected from the theory for the reaction-dominated regime. The reduction of the speed for one order of magnitude for 0.2mol% RGD-lipid represents the onset of the diffusion-controlled regime.
Biophysical Journal  , DOI: ( /S (01) )
Copyright © 2001 The Biophysical Society Terms and Conditions

6. Figure 5
The front exhibits concave and convex regions in the square-root regime of motion (a, b), but is relatively smooth in the regime of motion with a constant velocity. (a, b) Formation of a small region of a weak adhesion (inclusion) trapped in the domain of the tight adhesion. (a) The inclusion formation begins with growing of two “arms” forming an invagination of the weakly adhered membrane (arrow). (b) Closing of the arms results in the trapping of the inclusion. Two successive images (a) and (b) are separated by one second. The adhering vesicle contains 0.08mol% RGD- and 1mol% PEG-lipid. The bars in the left lower corner of the images represent 5μm.
Biophysical Journal  , DOI: ( /S (01) )
Copyright © 2001 The Biophysical Society Terms and Conditions