mediated amperometric immunosensing using single walled carbon nanotube forests a prototype amperometric immunosensor was evaluated based on the adsorption of antibodies onto perpendicularly oriented assemblies of single wall carbon nanotubes called swnt forests the forests were selfassembled from oxidatively shortened swnts onto nafioniron oxide coated pyrolytic graphite electrodes the nanotube forests were characterized using atomic force microscopy and resonance raman spectroscopy antibiotin antibody strongly adsorbed to the swnt forests in the presence of a soluble mediator the detection limit for horseradish peroxidase hrp labeled biotin was 25 pmol ml1 25 nm unlabelled biotin was detected in a competitive approach with a detection limit of 16 nmol ml1 16 microm and a relative standard deviation of 12 the immunosensor showed low nonspecific adsorption of biotinhrp approx 01 when blocked with bovine serum albumin this immunosensing approach using high surface area patternable conductive swnt assemblies may eventually prove useful for nanobiosensing arrays