Substrate-dependent kinetics in tyrosinase-based biosensing: Amperometry vs. spectrophotometry

Despite the broad use of enzymes in electroanalytical biosensors, the influence of enzyme kinetics on the function of prototype sensors is often overlooked or neglected. In the present study, we employ amperometry as an alternative or complementary method to study the kinetics of tyrosinase, whose catalytic activity results in o-quinone products...

Electrochemical Correlation Spectroscopy (ECS) in Nanofluidic Channels

Towards Electrochemical Detection of Single Molecules: Redox Cycling in Nanofluidic Devices

Nanofluidic Redox Cycling for Localized Detection of Chemical Gradients

Redox cycling in nanofluidic channels using interdigitated electrodes

Amperometric detection is ideally suited for integration into micro- and nanofluidic systems as it directly yields an electrical signal and does not necessitate optical components. However, the range of systems to which it can be applied is constrained by the limited sensitivity and specificity of the method. These limitations can be partially...

Carbon nanotube biosensors: The critical role of the reference electrode

Carbon nanotube transistors show tremendous potential for electronic detection of biomolecules in solution. However, the nature and magnitude of the sensing signal upon molecular adsorption have so far remained controversial. Here, the authors show that the choice of the reference electrode is critical and resolves much of the previous...

Role of tension and twist in single-molecule DNA condensation

Charge inversion at high ionic strength studied by streaming currents

Integration of a gate electrode into carbon nanotube devices for scanning tunneling microscopy

We have developed a fabrication process for incorporating a gate electrode into suspended single-walled carbon nanotube structures for scanning tunneling spectroscopy studies. The nanotubes are synthesized by chemical vapor deposition directly on a metal surface. The high temperature (800?°C) involved in the growth process poses challenging...

Scanning tunneling spectroscopy of suspended single-wall carbon nanotubes

We have performed low-temperature scanning tunneling microscopy measurements on single-wall carbon nanotubes that are freely suspended over a trench. The nanotubes were grown by chemical vapor deposition on a Pt substrate with predefined trenches etched into it. Atomic resolution was obtained on the freestanding portions of the nanotubes....

Direct Observation of Charge Inversion by Multivalent Ions as a Universal Electrostatic Phenomenon

Direct observation of confined states in metallic single-walled carbon nanotubes

We investigated the local density of states (LDOS) of extended individual metallic single-walled carbon nanotubes using low-temperature scanning tunneling spectroscopy. We observed that the LDOS oscillates with energy close to the Fermi level. The oscillation period of about 50 meV varies with position on the nanotube. Maps of the LDOS reveal...