We have achieved, for the first time, the selective patterning of centrosomes onto solid substrates. The use of such patterned centrosome arrays astemplates for the directed polymerization of microtubules was also demonstrated. Centrosomes are small organelles in animal cells that serve as nucleation and. organization centers of microtubules. Directed assembly of microtubules on the patterned centrosome arrays provides a new route to control the positions and directions of microtubules on surfaces. Combining the patterning of the isolated centrosomes and the directed growth of microtubules may lead to the generation of desired microtubule networks for bio-based nanodevices. (c) 2006 Wiley Periodicals, Inc.