Surface-morphology-induced oriented growth in natural and artificial tip-growing systems*

Tip growth is a growth scheme adopted by various cells that transcend species, as exemplified by pollen tubes and root hairs of plants, and germ tubes of fungi. We have previously developed an artificial tip-growing system based on non-solvent induced phase separation (NIPS) of a polymer solution. With the goal of enhancing our understandings of the tip-growing cells using the artificial system, we here show that on a linearly grooved surface, the tip-growing polymer precipitates tend to grow in the direction perpendicular to the pattern. We rationalize how the tip-growing scheme found in natural and artificial systems results in such surface-morphology-induced oriented growth. We also construct a theoretical model to predict the growth direction change upon passing the pattern, and validate the model using experimental results.