A particularly efficient redox mediator for electron transfer between FAD-dependent glucose dehydrogenase (FAD-GDH) and carbon nanotube (CNT) based electrodes can be obtained via electrosynthetic oxidation of pyrene in aqueous buffer solution. 1 H-NMR spectroscopic studies reveal the formation of a 2 : 1 mixture of 1,6-pyrenedione and 1,8-pyrenedione at the electrode. The formed pyrenedione exhibits a well-defined surface-bound redox system at À 0.1 V vs. SCE and provides excellent electron transfer kinetics with this enzyme. Further-more, the π-system of pyrenedione allows improved stacking behavior with the CNT walls, leading to enhanced stabilities compared to commonly used mediators like naphthoquinone. The electrosynthesis of pyrenedione for catalytic glucose oxidation is optimal at pH 2 using cyclic voltammetry or chronoamerometry. It is envisioned that the electrosynthetic methodology can be expanded to form different redox mediators for a series of enzymes.[a] Dr.
A series of polycyclic aromatics, naphthalene, phenanthrene, perylene, pyrene, 1-pyrenebutyric acid N-hydroxysuccinimide ester (pyrene NHS) and coronene, were immobilized via π stacking on carbon nanotube (CNT) electrodes and electro-oxidized in...
Biosensors are essential tools in the health and the environmental sectors since they allow fast and reliable diagnostics and analysis. Biosensors are defined by the biological sensing element, which contains biomolecules or synthetic, bioinspired entities with unique specificity towards the analyte. The biological or bioinspired recognition even can be transduced into an electric, electrochemical, or optical signal. A constant challenge for the development of biosensors is the confinement of these selective entities in devices without altering the biological activity. Polymers are great candidates to serve as substrates for the immobilization or entrapment of bioreceptors related to well established synthesis routes with highly modulable chemical functions to create an almost ideal environment for the biomolecules. Nanomaterials are of constant increasing interest since they allow not only to increase drastically the specific surface for higher amounts of receptor units, but also provide electric or optical properties leading to enhanced signal capture. As for bioreceptors, such nanomaterials can be integrated polymer matrices for reliable processability. This review aims to summarize selected original examples about biosensors for health monitoring using beneficial combinations of nanomaterials and polymers.
A series of new glyconanoparticles (GNPs) was obtained by self-assembly by direct nanoprecipitation of a mixture of two carbohydrate amphiphilic copolymers consisting of polystyrene-block-β-cyclodextrin and polystyrene-block-maltoheptaose with different mass ratios, respectively 0–100, 10–90, 50–50 and 0–100%. Characterizations for all these GNPs were achieved using dynamic light scattering, scanning and transmission electron microscopy techniques, highlighting their spherical morphology and their nanometric size (diameter range 20–40 nm). In addition, by using the inclusion properties of cyclodextrin, these glyconanoparticles were successfully post-functionalized using a water-soluble redox compound, such as anthraquinone sulfonate (AQS) and characterized by cyclic voltammetry. The resulting glyconanoparticles exhibit the classical electroactivity of free AQS in solution. The amount of AQS immobilized by host–guest interactions is proportional to the percentage of polystyrene-block-β-cyclodextrin entering into the composition of GNPs. The modulation of the surface density of the β-cyclodextrin at the shell of the GNPs may constitute an attractive way for the elaboration of different electroactive GNPs and even GNPs modified by biotinylated proteins.
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