A heated oxide covered copper electrode (HOCE) was facilely fabricated for the first time, providing a highly enhanced electrocatalytic oxidation, and cost effective and sensitive determination for polyhydroxy compounds such as glucose and shikimic acid.

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A nanocomposite of CdSe quantum dots with nitrogen-doped carbon nanotubes was prepared for enhancing the electrochemiluminescent (ECL) emission of quantum dots. With hydrogen peroxide as co-reactant, the nanocomposite modified electrode showed a cathodic ECL emission with a starting potential of À 0.97 V (vs. Ag/AgCl) in phosphate buffer solution, which was five-times stronger than that from pure CdSe quantum dots and three-times stronger than that from CdSe quantum dots composited with carbon nanotubes. The latter showed a starting potential of À 1.19 V. This result led to a sensitive ECL sensing of hydrogen peroxide with good stability, acceptable reproducibility and a detection limit down to 2.1 Â 10 À7 mol L À1. Nitrogen-doped carbon nanotubes could be used as a good material for the construction of sensitive ECL biosensors for chemical and biochemical analysis.

A new electrochemiluminescent (ECL) biosensor based on an electrically heated carbon paste electrode (HCPE) that was surface modified by xanthine oxidase (XOD) was designed and constructed in this work. It was found that the ECL intensity of luminol could be enhanced at the surface of XOD/HCPE by adding hypoxanthine (HX) to the solution, and there was a linear relationship between the ECL intensity and the concentration of HX. On the basis of this, an ECL enzyme biosensor can thus be developed to detect HX. However, because the activity of XOD is highly dependent on temperature, the biosensor is very sensitive to the temperature of the electrode. Also, because the temperature of the electrode may also affect the diffusion and convection of the luminescent compounds near the electrode surface, a suitable temperature for XOD/HCPE has to be controlled to achieve the best ECL signal. The key feature of the designed biosensor is that the temperature of the electrode is controllable so the most suitable temperature for the enzyme reaction can be obtained. The obtained results showed that the ECL enzyme biosensor exhibited the best sensitivity at an electrode temperature of 35 degrees C for the detection of HX. The detection limit was 30-fold lower than that at room temperature (25 degrees C).