Amperometric detection of L-lactate using nitrogen-doped carbon nanotubes modified with lactate oxidase.

Nitrogen-doped carbon nanotubes (N-CNTs) provide a simple, robust, and unique platform for biosensing. Their catalytic activity toward the oxygen reduction reaction (ORR) and subsequent hydrogen peroxide (H(2)O(2)) disproportionation creates a sensitive electrochemical response to enzymatically generated H(2)O(2) on the N-CNT surface, eliminating the need for additional peroxidases or electron-transfer mediators. Glassy carbon electrodes were modified with 7.

Buckysomes: fullerene-based nanocarriers for hydrophobic molecule delivery.

We report the preparation and preliminary in vitro studies of nanocarriers termed "buckysomes," which are self-assembled, spherical nanostructures composed of the amphiphilic fullerene AF-1. By inducing AF-1 self-assembly at an elevated temperature of 70 degrees C, dense spherical buckysomes with diameters of 100-200 nm were formed, as observed by electron microscopy and dynamic light scattering. The amphiphilic nature of AF-1 results in the formation of many hydrophobic regions within the buckysomes, making them ideal for embedding hydrophobic molecules to be tested in a drug delivery scheme.

Anomalous electrochemical dissolution and passivation of iron growth catalysts in carbon nanotubes.

Catalytically synthesized carbon nanotubes (CNTs) such as those prepared via chemical vapor deposition (CVD) contain metallic impurities including Fe, Ni, Co, and Mo. Transition metal contaminants such as Fe can participate in redox cycling reactions that catalyze the generation of reactive oxygen species and other products. Through the nature of the CVD growth process, metallic nanoparticles become encased within the CNT graphene lattice and may still be chemically accessible and participate in redox chemistry, especially when these materials are utilized as electrodes in electrochemical applications.

Direct electrochemical and spectroscopic assessment of heme integrity in multiphoton photo-cross-linked cytochrome C structures.

Multiphoton excitation (MPE) lithography offers an effective, biocompatible technique by which three-dimensional architectures comprised of proteins, enzymes, and other relevant materials may be fabricated for use in biological studies involving cellular signal transduction and neuronal networking. We present a series of studies designed to investigate the integrity of cytochrome c (cyt c) photo-cross-linked via MPE. Specifically, we have used electrochemical methods and surface-enhanced Raman spectroscopy (SERS) to determine whether photo-cross-linked cyt c retains its well-characterized Fe(II/III) heme redox activity.

Picomolar peroxide detection using a chemically activated redox mediator and square wave voltammetry.

A method for low-level, low-potential electrochemical detection of hydrogen peroxide using a chemically activated redox mediator is presented. This method is unique in that it utilizes a mediator, Amplex Red, which is only redox-active when chemically oxidized by H2O2 in the presence of the enzyme horseradish peroxidase (HRP). When employed in concert with microelectrode square wave voltammetry to optimize sensing at ultralow concentrations (<1 microM), this method exhibits marked improvements in analytical sensitivity and detection limits (limit of detection as low as 8 pM) over existing protocols.

Microfabrication of three-dimensional bioelectronic architectures.

The functionality and structural diversity of biological macromolecules has motivated efforts to exploit proteins and DNA as templates for synthesis of electronic architectures. Although such materials offer promise for numerous applications in the fabrication of cellular interfaces, biosensors, and nanoelectronics, identification of techniques for positioning and ordering bioelectronic components into useful patterns capable of sophisticated function has presented a major challenge. Here, we describe the fabrication of electronic materials using biomolecular scaffolds that can be constructed with precisely defined topographies.