Adamantane/β-cyclodextrin affinity biosensors based on single-walled carbon nanotubes

One challenging goal for the development of biosensors is the conception of three-dimensional biostructures on electrode surfaces. With the aim to develop 3D architectures based on single-walled carbon nanotubes (SWCNTs) frameworks a novel adamantane-pyrrole monomer was synthesized. After electrochemical polymerization at 0.95 V in acetonitrile, the resulting polypyrrole film provided affinity interactions with β-cyclodextrin. SWCNT coatings were thus functionalized with poly(adamantane-pyrrole) and applied to the anchoring of glucose oxidase (GOX), modified with β-cyclodextrin. By using this affinity system adamantine–cyclodextrin, β-cyclodextrin-modified gold nanoparticles were attached onto the functionalized SWCNT deposit as intermediate layer. This allows the immobilization of adamantane-tagged GOX. The responses of these biosensors to glucose were measured by potentiostating the modified electrodes at 0.7 V versus saturated calomel electrode (SCE) in order to oxidize the enzymatically generated hydrogen peroxide in the presence of glucose and oxygen. The highest sensitivity and maximum current density were recorded for the configuration based on β-cyclodextrin-modified gold particles as intermediate layer between adamantine-functionalized SWCNTs and GOX (31.02 mA M−1cm−2 and 350 μA cm−2, respectively). The similar configuration without SWCNTs exhibits a sensitivity and Jmax of 0.98 mA M−1cm−2 and 75 μA cm−2, respectively. The resulting supramolecular assemblies were characterized by scanning electron microscopy (SEM). Advantages and disadvantages of the different preparation methods and the performance of each affinity sensor setup are discussed in detail.