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A novel platinum–palladium nanoparticle-decorated carbon nanofiber nanocomposite was greenly prepared by attaching the nanoparticles to the nanofibers for the preparation of glucose biosensors. The platinum–palladium bimetallic nanoparticle-modified carbon nanofiber nanocomposite was characterized by transmission electron microscopy, X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The glucose biosensor was constructed by immobilizing glucose oxidase on the nanocomposite-modified glassy carbon electrode by cross-linking with glutaraldehyde. The resulting biosensor exhibited a good response to glucose with a wide linear range from 2.5 × 10−6to 1.3 × 10−2 M with a high sensitivity of 154.6 µA mM−1cm−2and a detection limit of 0.7 µM. This biosensor was shown to offer good accuracy, precision, and reproducibility. The determination of glucose in human serum by the modified electrode was in good agreement with standard values. The nanocomposite electrode offers a suitable platform for the determination of glucose. [ABSTRACT FROM AUTHOR]

A novel electrochemically-based biosensor was developed for the determination of hydrazine by modifying a glassy carbon electrode with an aqueous dispersion of carboxylic group-functionalized carbon nanofiber/chitosan solution, and then absorbing hemoglobin on the surface of chitosan-carbon nanofibers. Nafion was used to coat the hemoglobin membrane. The interactions of hemoglobin and the nafion/chitosan-carbon nanofibers were investigated by ultraviolet-visible absorption, infrared, and circular dichroism spectroscopies. The results indicated that the native structure of hemoglobin was retained post-immobilization. The circular dichroism results showed that the α-helical structure of hemoglobin was preserved though a small change was observed in the presence of the nafion/chitosan-carbon nanofibers. The modified nanofibers were further characterized by scanning electron microscopy, electron impendence spectroscopy, and cyclic voltammetry. The electrocatalytic mechanism of hemoglobin to the oxidation of hydrazine was investigated and an irreversible diffusion-controlled electrode process was obtained. The electron transfer rate constant (ks), transfer coefficient (α), and Michaelis–Menten constant (Km) were also evaluated. The peak current of the catalytic oxidation was linear with hydrazine concentration from 3.722 × 10−5to 1.601 × 10−3molar with a correlation coefficient of 0.995. The detection limit was estimated to be 2.7 micromoles per liter. The sensitivity, stability, and reproducibility of the nafion/hemoglobin/chitosan-carbon nanofiber/glassy carbon electrode for the oxidation of hydrazine were also investigated. [ABSTRACT FROM AUTHOR]

Carbon nanomaterials are in the forefront of research in a variety of chemical and physical disciplines. Of these, certain nanostructures seem to be suitable for the development of electrochemical biosensors. In particular carbon nanotubes, and carbon nanofibers have specific chemical and physical characteristics that lent them ideal for the development of biosensors with unique analytical characteristics. In particular, their conductivity, surface area, inherent and induced chemical functionalities, and biocompatibility provide the grounds for the development of a new era of electrochemical biosensors. In this review, we will examine the recent developments of biosensor design based on these new nanostructures. [ABSTRACT FROM AUTHOR]

Systematic investigations were carried out into the sorption of rare earth elements (REEs) on carbon nonofibers (CNFs) by inductively coupled plasma mass spectrometry (ICP-MS). The experimental parameters for preconcentration of REEs, such as pH, sample flow rate and volume, eluent concentration, and interfering ions on preconcentration of REEs have been examined in detail. The studied metal ions can be adsorbed quantitatively on CNFs in a pH range from 2.0 to 5.0, and then eluted completely with 0.5 mol l-1 HNO3. Based on the above facts, a novel method using a microcolumn packed with carbon nanofibers as an adsorption material was developed for the separation and preconcentration of REEs prior to their determination by ICP-MS. The proposed method has been successfully applied to the determination of light (La), medium (Eu and Gd) and heavy (Yb) rare earth elements in real sample with the recovery more than 90%. In order to validate this method, two certified reference materials of tea leaves (GBW 07605) and mussel (GBW 08571) were analyzed, and the determined values are in good agreement with the certified values. [ABSTRACT FROM AUTHOR]