Sensitive Enzyme-free Sensor Research Articles

Shape-Controlled Gold Nanoarchitectures: Synthesis, Superhydrophobicity, and Electrocatalytic Properties

A simple one-step electrodeposition method was used to fabricate various gold nanostructures on glassy carbon electrodes in a low concentration of HAuCl4 solution (5 mM). The morphologies of final gold nanostructures can be easily controlled by varying the pH of the precursors or the deposition temperature. X-ray powder diffraction, scanning electronic microscopy, transmission electron microscopy, contact angle measurements, and electrochemical methods were used to characterize them. Hierarchical waxberry-like gold nanostructures with high active surface areas were obtained in pH 4 bath, and they had a higher catalytic performance for the reduction of oxygen than the other nanogold. These gold structures also displayed an extraordinary superhydrophobicity and the contact angle increased with the increase of deposition temperature and time. Their electrocatalytic response to the oxidation of glucose was also investigated. A sensitive enzyme-free sensor can be easily developed for the detection of glucose in pH 7.4 phosphate buffer solution.

Fabrication, characterization and application of gold nano-structured film

A straightforward, rapid and “green” approach was proposed for the fabrication of gold nano-structured films. A gold electrode was firstly oxidized under a high potential of 10 V, and β- d-glucose, as a nontoxic reducing agent, was then chosen to reduce the gold oxide. This process gives a fractal gold nanofilm on the top of the gold electrode in a way of completely “green” chemistry. X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy and electrochemical methods were adopted to characterize the as-prepared gold nanofilm. The gold nanofilm was found to have abundant adatom state Au ∗, evidenced by the electrochemical process of Au ∗/Au ∗OH ads couple. The as-prepared gold nanofilm greatly facilitates the electrochemical oxidation of glucose in neutral solutions. As the gold nanofilm was formed in situ on the gold electrode, additional immobilization procedures are not necessary. A sensitive enzyme-free sensor can be easily developed for the detection of glucose in pH 7.4 phosphate buffer solution, which gives linear ranges up to 57.5 and 30 mM with detection limits down to 0.75 and 3.6 μM at potential of +0.3 and −0.15 V, respectively. A rapid response for glucose could be achieved in less than 2 s. At a detection potential of −0.15 V, physiological interference agents such as ascorbic acid, uric acid and acetylaminophenol were efficiently excluded.