This Letter reports the first example of the functionalization. of single wall carbon nanotubes (SWNTs) with an enzyme via the formation of a covalent bond as shown particularly by Fourier transform infrared spectroscopy. Functionalization with enzymes was achieved first by acylation of the nanotubes, and was then followed by amidation. Various primary and secondary achiral and chiral amines were also tethered to the SWNTs by this method. Covalent functionalization of carbon nanotubes offers the architecture for a three-dimensional enzyme array for potential application in biosensor devices. (C) 2004 Elsevier B.V. All rights reserved.