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Ultralow Pt-loading Au nanoflowers (AuNFs) were synthesized on a glassy carbon electrode surface by the underpotential deposition (UPD) monolayer redox replacement technique, which involves redox replacement of a copper UPD monolayer by PtCl(4)(2-) that can be reduced and deposited simultaneously. Field-emission scanning electron microscopy, energy dispersive spectroscopy, x-ray photoelectron spectroscopy and the electrochemical method were utilized to characterize the ultralow Pt-loading AuNFs. Cyclic voltammogram results showed that the ultralow Pt-loading AuNFs exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide and the oxidation of glucose in neutral media, and the reaction pathway of glucose oxidation was changed from an intermediate process based on the electrosorption of glucose to a direct oxidation process. From chronoamperometric results, it could be obtained that this prepared biosensor had wide linear ranges and very low detection limits (DLs) for H(2)O(2) (0.025-94.3 μM; DL = 0.006 μM) and glucose (0.0028-8.0 mM; DL = 0.8 μM), which were much better than previous results.

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A novel carboxyl-group functionalized silicate nanopore films (SNFs) was successfully fabricated on Pt electrode by immobilization of the composite material containing polyacrylic acid (PAA) and tetraethyl orthosilicate (TEOS). The composite films have relatively uniform pores with an average of 20 nm in diameter and are endowed with a great amount of carboxyl groups, which provided large amount of negative charge on film surface. Scanning electron microscope (SEM), Transmission electron microscope (TEM) images, EDS spectrum and FTIR spectrum have been used to characterize the prepared SNFs. Three redox species with different charge, including hexacyanoferrate (Fe(CN)63−), hexaamino-ruthenium (Ru(NH3)63+) and ferrocene methanol (FcMeOH) in different pH, were employed to investigate the permselectivity of the SNFs modified electrode. The results showed that the SNFs modified electrode favored the mass transport of oppositely charged species (Ru(NH3)63+), repelled similarly charged species (Fe(CN)63−), and had little effect on the transport of neutral species (FcMeOH). Based on this good permselective property, the prepared SNFs modified electrode was employed to detect dopamine (DA) in the presence of ascorbic acid (AA) at pH 7.6. The prepared SNFs electrode exhibited a good sensing performance for detection of DA with the linear range of 10–1900 μM and the detection limit of 1.7 μM (S/N = 3).