Selective adhesion of functional microtubules to patterned silane surfaces

We show that microtubule polymers can be immobilized selectively on lithographically patterned silane surfaces while retaining their native properties. Silane films were chemisorbed on polished silicon wafers or glass coverslips and patterned using a deep UV lithographic process developed at the Naval Research Laboratory. Hydrocarbon and fluorocarbon alkyl silanes, as well as amino and thiol terminal alkyl silanes, were investigated as substrates for microtubule adhesion with retention of biological activity. Microtubules were found to adhere strongly to amine terminal silanes while retaining the ability to act as substrates for the molecular motor protein kinesin. Aminosilane patterns with linewidths varying from 1 to 50 mu m were produced lithographically and used to produce patterns of selectively adhered microtubules. Microtubules were partially aligned on the patterned lines by performing the immobilization in a fluid flow field. Patterns were imaged with atomic force microscopy and differential interference contrast microscopy. Motility assays were carried out using kinesin-coated beads and observed with differential interference contrast microscopy. Kinesin bead movement on the patterned microtubules was comparable to movement on microtubule control surfaces.