Modulating Adhesion and Dynamics of F-actin on Polymer Hydrogels

J-H. Park, Y. Sun, Y. E. Goldman, R. J. Composto

Motivation:

• Soft nanostructures are tunable templates for immobilizing/patterning biomolecules (e.g.F-actin , proteins).
• Precise control over molecule location will allow development of new biomolecular devices utilizing molecular motors as well as high-throughput protein/gene identification.

Objective:

• Demonstrate that the interaction between a stiff biomolecule, F-actin, and a hydrogel substrate can be tuned by varying the surface charge on the substrate.

Results:

• At low surface charge, F-actin interacts weakly with the substrate (left below).
• At intermediate surface charge, F-actin lies flat on the substrate and coverage increases (middle).
• At high surface charge, F-actin are immobilized on the surface but, surprisingly, the coverage decreases. This decrease is attributed to an increase in surface roughness that reduces molecule-substrate contact (right).

Conclusions:

These results demonstrate that surface charge alone does not control biomolecular attachment but rather charge and surface roughness are key design features for optimizing highly efficient devices.