A nanotube mat is provided with an array of conduits to support, direct growth, select or interface one or more biological cells or cell processes. The carbon nanotube mat provides mechanical stability, is biocompatible, will support cell growth, can desirably be derivatized with growth factors, molecules, nutrients, inhibitory factors, ligands, transduction molecules or morphogenic factors, and would allow the formation of conduits to guide cells and cell extensions to be hosted or grown. The conduits could take any size or shape to support, direct growth, select or interface one or more cells or processes. In general the conduits could be channels, discontinuous channels, tapered channels or walls. The nanotube mat could be used to interface biological cells with other cells, tissue or structures that have electrical, mechanical, magnetic means, or optical means. The nanotube mat could also incorporate chemicals, analytes, drugs, lips, carbohydrates, secretory products or the like.