Supplementary Information for. Blood-Clotting Inspired Reversible Polymer-Colloid. Composite Assembly in Flow

Transcription

1 Supplementary Information for Blood-Clotting Inspired Reversible Polymer-Colloid Composite Assembly in Flow Hsieh Chen 1, Mohammad A. Fallah 2,3, Volker Huck 4, Jennifer I. Angerer 2,3, Armin J. Reininger 5, Stefan W. Schneider 4, Matthias F. Schneider 3 and Alfredo Alexander-Katz 1 * 1 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA 2 Experimental Physics I, University of Augsburg, Augsburg 86159, Germany 3 Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA 4 Department of Dermatology, Venereology and Allergology, Experimental Dermatology, Medical Faculty Mannheim, Heidelberg Ruprecht-Karls-University, Mannheim, Germany 5 Baxter Innovations GmbH, Vienna, Austria * aalexand@mit.edu 1

2 No Flow With Flow Supplementary Figure S1 Schematics of shear-induced vwf-colloids and vwfplatelets aggregates. Combined interference contrast microscopy and fluorescence images of vwf-colloids mixtures (top) and vwf-platelets mixtures (bottom), respectively, before (left) and under flow (right). Experiments were performed in whole blood, for vwf-colloids mixtures platelets were substituted. At a shear rate of 4,000 s -1 (right) reversible aggregates come to existence rolling on the vwf-coated surface, dissolving after reducing the shear rate. Scale bars correspond to 50 µm. Number of experimental repeats = 6. 2

3 Supplementary Figure S2 Pure colloidal (control) system and diffusion-limited aggregation. In this simulation we apply the same model used for polymer-colloid interactions to colloid-colloid interactions, and explore the aggregation of such pure colloid systems. (a) Average number of colloid-colloid bonds as a function of the shear rates with different unbinding energies. (Inset in a: Snapshot of colloid aggregates with E UB = 9 k B T at = 0.05.) (b) Number of colloid-colloid bonds as a function of the simulation time t/τ when suddenly switching the shear rates between the maximum and 3

4 minimum values. As observed, the pure adhesive colloid system is very different from the polymer-colloid mixtures. First, to form aggregates, we have to increase the unbinding energies to as high as E UB = 9 k B T. Second, for E UB = 9 k B T, the aggregates form at shear rates as low as = 0.05 and break for higher shear rates. Last and most important, the aggregation process of the pure adhesive colloids is not reversible. When switching the shear rates between high and low values, we find no significant changes of the number of bonds. Thus, this control system which is diffusion limited shows why low shear conditions help in the formation of the aggregates is actually qualitatively different from the polymer-colloid system. 4

5 Supplementary Figure S3 Limiting shear-enhanced aggregation at extremely high shear rates. (a) Average number of polymer-colloid bonds for E UB = 6 k B T at shear rates 0.01 < < 10. Inset in a: Snapshot of the mixture containing colloids and collapsed polymers (u = 2.08 k B T) at = 10. (b) Probability distribution of the bond tension energies fr 0 at different shear rates measured from the simulations. As shown, the average number of bonds reaches a maximum at ~ 5 and decreases when increasing the shear rates further. The decreasing of bond numbers here at extremely high shear rates is caused by the increased bond tension energies that rapidly increase the unbinding probabilities (see Methods). 5

6 No Flow With Flow Supplementary Figure S4 Formation of shear-induced colloid aggregates depends on freely floating vwf. Combined interference contrast microscopy and fluorescence images of colloids (top) and platelets (bottom), respectively, before (left) and under flow (right). Experiments were performed in whole blood, for colloid experiments platelets were substituted. Without addition of freely floating vwf, colloidal aggregation was not detectable, and the effect of the increased flow was only to have more rolling platelets/colloids on the vwf coated surface. Scale bars correspond to 50 µm. Number of experimental repeats = 4. 6

7 No Flow With Flow Supplementary Figure S5 Inhibition of GPIb-α impedes shear-induced colloidpolymer composite assembly. Combined interference contrast microscopy and fluorescence images of vwf-platelets mixtures supplemented with a specific inhibitor of GPIb-α receptor before (left) and under flow (right). Experiments were performed in whole blood. Under specific inhibition of the GPIb receptor-vwf A1 domain interaction no colloid-polymer composite assembly was detectable. Scale bars correspond to 50 µm. Number of experimental repeats = 4. 7

8 Supplementary Figure S6 Conformation of polymers in aggregates. (a) Normalized polymer radius of gyration <R 2 g >/Na 2, (b) bound colloids per polymer, and (c) bound polymers per colloid as functions of shear rates with different unbinding energies and types of polymers. At the onset of aggregation, R g is close to and slightly higher than the colloid radius r c, suggesting that the polymers either wrap around or slightly extend over the colloids. In addition, the polymers are efficient linking agents. For the most compact aggregates, in average one polymer chain connects to about three colloids, and one single colloid is connected with twelve polymers. 8