Nanocube-Nanotube Biosensors

Networks of single-walled carbon nanotubes decorated with metallic nanocubes can serve as highly sensitive detectors for measuring biomolecules over a wide range of concentrations, according to a new study in ACS Nano (DOI: 10.1021/nn800682m). Purdue University engineers Timothy S. Fisher, D. Marshall Porterfield, and coworkers capitalized on a technique they developed previously for growing nanotubes vertically on top of a silicon wafer by augmenting the nanotubes with gold-coated palladium nanocubes. The nanocubes, which grow via electrodeposition and are tethered to the nanotubes, serve as docking points for attaching biomolecules and as electrocatalysts that facilitate the detection process. Testing the devices' performance as electrochemical sensors for glucose, the Purdue team attached glucose oxidase to the nanocubes via thiol linkages and found that the sensors exhibit a detection limit of about 1 µM and a linear response between 10 µM and 50 mM. Those values represent a performance enhancement of roughly a factor of five compared with other glucose sensors based on carbon nanotubes and metallic nanoparticles and nanowires, the team says.