Controlling the covalent bonding of antibodies onto functionalized carbon nanotubes is a key step in the design and preparation of nanotube-based conjugates for targeting cancer cells. For this purpose, an anti-MUC1 antibody (Ab) is linked to both multi-walled (MWCNTs) and double-walled carbon nanotubes (DWCNTs) using different synthetic strategies. The presence of the Ab attached to the nanotubes is confirmed by gel electrophoresis and thermogravimetric analysis. Most importantly, molecular recognition of the antigen by surface plasmon resonance is able to determine similar Ab binding capacities for both Ab-DWCNTs and Ab-MWCNTs. These results are very relevant for the design of future receptor-targeting strategies using chemically functionalized carbon nanotubes. Antibody-carbon nanotube (Ab-CNT) conjugates are synthesized through two covalent approaches and then characterized. The interaction between anti-MUC1 Ab-CNT conjugates and the Ab antigen is monitored by the surface plasmon resonance technique. The results support the development of systems based on the targeting properties of CNTs functionalized with antibodies. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.