We report on the analytical performance of boron‐doped diamond thin‐film electrodes for the detec... more We report on the analytical performance of boron‐doped diamond thin‐film electrodes for the detection of the virulence factor, pyocyanin (PYO). The results reported herein confirm the utility of diamond electrodes for the sensitive and reproducible detection of pyocyanin in a 0.1 mol L−1 phosphate buffer (pH 7.4) when using amperometric detection coupled with flow injection analysis (FIA) or square wave voltammetry (SWV). Pyocyanin was reductively detected by hydrodynamic voltammetry in FIA at an E1/2 of −0.31 V vs. Ag/AgCl (3 mol L−1 KCl). The detection figures of merit were a linear dynamic range from 100 to 0.08 μmol L−1, a response reproducibility of 1.3 % (RSD), and a limit of detection of 0.09 μmol L−1 (S/N=3). A comparable linear dynamic range, response reproducibility and limit of detection were observed in preliminary square wave voltammetry measurements. Importantly, these detection figures of merit were obtained using boron‐doped diamond electrodes that received no conven...
Isatin is an endogenous indole compound in humans and rodents that has a wide range of biological... more Isatin is an endogenous indole compound in humans and rodents that has a wide range of biological activity. In rat models, isatin concentrations have been shown to increase in the heart, brain, blood plasma, and urine with stress. Studies on patients suffering from Parkinson's disease have indicated a correlation between progress of the disease and urinary output of the molecule. Isatin is electrochemically active and can therefore be detected with electrochemical techniques. In this work, we compared the performance of a nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C:N) and a boron‐doped nanocrystalline diamond thin‐film electrode for the oxidative detection of this biomolecule using flow injection analysis with amperometric detection. The measurements were performed in 0.1 phosphate buffer pH 7.2. The ta‐C:N electrode, like boron‐doped nanocrystalline diamond, exhibits some excellent properties for electroanalytical measurements including (i) low background current a...
Room temperature ionic liquids (RTILs) have a wide range of current and potential applications, i... more Room temperature ionic liquids (RTILs) have a wide range of current and potential applications, in areas ranging from supercapacitor energy storage to sequestration of toxic gas phase species and use as reusable solvents for selected organic reactions. All these applications stem from their unique physical and chemical properties, which remain understood to only a limited extent. Among the issues of greatest importance is the extent to which RTILs exist as dissociated ionic species and the length scales over which some types of organizations are seen to exist in them. In this Invited Feature Article, we review the current understanding of organization in this family of materials, where opportunities lie in terms of deepening our understanding, and what potential applications would benefit from gaining such knowledge.
The electrochemical properties of a nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C:N) t... more The electrochemical properties of a nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C:N) thin‐film electrode were investigated. Cyclic voltammetry was used to investigate the background current response as a function of potential, scan rate, and electrolyte composition. Cyclic voltammetry and digital simulation were used to determine the heterogeneous electron‐transfer rate constants (ko) for IrCl62−/3−, Fe(CN)63−/4−, ferrocene carboxylic acid, Ru(NH3)63+/2+, and methyl viologen. The results revealed that the background current for the ta‐C:N electrode falls between that of BDD and GC. ko values for all the redox analytes at ta‐C:N were comparable to the values at BDD and GC. ko values were lower for Fe(CN)63−/4−, 10−3 cm s−1, than for the other four redox systems, 10−2–10−1 cm s−1. ko for Ru(NH3)63+/2+ was insensitive to the electrolyte cation (Li+, Na+, K+, and Cs+) at all three electrodes. In contrast, ko for Fe(CN)63−/4− was sensitive to the cation type with the greatest ...
We report on the analytical performance of a tetrahedral amorphous carbon (ta-C:N) thin-film elec... more We report on the analytical performance of a tetrahedral amorphous carbon (ta-C:N) thin-film electrode in flow injection analysis with amperometric detection. Two model redox analytes were used to evaluate the electrode response because of their positive detection potentials and propensity (i.e., reaction products) to adsorb and foul sp(2) carbon electrodes: tyrosine and tryptophan. ta-C:N electrodes are attractive for electroanalytical applications because they possesses many of the excellent properties of boron-doped nanocrystalline diamond (BDD) and they can be deposited at or near room temperature. The results show that the ta-C:N electrode exhibits lower background current and noise than glassy carbon (GC). The electrode was stable microstructurally at the positive potentials used for detection, ∼1.1 V, of these two amino acids and it exhibited superior analytical detection figures of merit as compared to GC and as good or superior to BDD. The linear dynamic range for both anal...
The oxidation reaction mechanism of several aliphatic polyamines was studied using diamond electr... more The oxidation reaction mechanism of several aliphatic polyamines was studied using diamond electrodes with different doping levels and non‐diamond carbon impurity content. The important roles of surface boron and localized non‐diamond carbon sites in the polyamine oxidation reaction mechanism were confirmed. A well defined oxidation peak was seen for all the amines that was dependent on the onset potential for water discharge. Epox shifted negative and the ipox increased with increasing solution pH. ipox also increased with increasing boron doping level or surface boron site density. FIA‐EC analysis revealed a reproducible response for the aliphatic polyamines in a binary solvent (7/93 %) acetonitrile/borate buffer, pH 11.2. Optimum signal‐to‐background ratios for the aliphatic polyamines were seen at potentials between 650 and 670 mV.
Abstract Boron-doped TiO2 (B/TiO2) nano-materials were synthesized by a sol–gel method and charac... more Abstract Boron-doped TiO2 (B/TiO2) nano-materials were synthesized by a sol–gel method and characterized by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrum (FT-IR) and UV–vis diffuse reflectance spectra (DRS). With the test of bacterial inhibition zone, the antibacterial properties of B/TiO2 nano-materials on Escherichia coli were investigated. The results show that the structure of TiO2 could be transformed from amorphous to anatase and then to rutile by increasing calcination temperature; part of the boron atoms probably have been weaved into the interstitial TiO2 structure or incorporated into the TiO2 lattice through occupying O sites, whereas others exist as B2O3. The results of antibacterial experiment under visible light irradiation show that the B/TiO2 nano-materials exhibit enhanced antibacterial efficiency compared with non-doped TiO2. Ultimately, the action mechanism of B/TiO2 doping is discussed.
Diamond thin-film electrodes have gained increased attention in recent years for electroanalysis ... more Diamond thin-film electrodes have gained increased attention in recent years for electroanalysis due to their wide working potential window for aqueous solvents, low background currents and increased signal to background repines as compared to conventional carbon-based electrodes. However, the relationship between the physical, chemical and electronic properties of diamond, and the observed electrochemical performance remains incompletely understood. For polycrystalline films, the electrochemical properties appear to be influenced in a complex manner by various factors which include, (i) the dopant type and concentration (i.e., electronic properties), (ii) morphological features such as grain boundaries, extended and point defects, and (iii) the non-diamond or amorphous carbon impurity content. The applicability of electroanalysis for biogenic amines and amino acids was investigated in alkaline media using cyclic voltammetry, and FIA-EC and LC-EC in the amperometric detection mode. ...
We report on the analytical performance of boron‐doped diamond thin‐film electrodes for the detec... more We report on the analytical performance of boron‐doped diamond thin‐film electrodes for the detection of the virulence factor, pyocyanin (PYO). The results reported herein confirm the utility of diamond electrodes for the sensitive and reproducible detection of pyocyanin in a 0.1 mol L−1 phosphate buffer (pH 7.4) when using amperometric detection coupled with flow injection analysis (FIA) or square wave voltammetry (SWV). Pyocyanin was reductively detected by hydrodynamic voltammetry in FIA at an E1/2 of −0.31 V vs. Ag/AgCl (3 mol L−1 KCl). The detection figures of merit were a linear dynamic range from 100 to 0.08 μmol L−1, a response reproducibility of 1.3 % (RSD), and a limit of detection of 0.09 μmol L−1 (S/N=3). A comparable linear dynamic range, response reproducibility and limit of detection were observed in preliminary square wave voltammetry measurements. Importantly, these detection figures of merit were obtained using boron‐doped diamond electrodes that received no conven...
Isatin is an endogenous indole compound in humans and rodents that has a wide range of biological... more Isatin is an endogenous indole compound in humans and rodents that has a wide range of biological activity. In rat models, isatin concentrations have been shown to increase in the heart, brain, blood plasma, and urine with stress. Studies on patients suffering from Parkinson's disease have indicated a correlation between progress of the disease and urinary output of the molecule. Isatin is electrochemically active and can therefore be detected with electrochemical techniques. In this work, we compared the performance of a nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C:N) and a boron‐doped nanocrystalline diamond thin‐film electrode for the oxidative detection of this biomolecule using flow injection analysis with amperometric detection. The measurements were performed in 0.1 phosphate buffer pH 7.2. The ta‐C:N electrode, like boron‐doped nanocrystalline diamond, exhibits some excellent properties for electroanalytical measurements including (i) low background current a...
Room temperature ionic liquids (RTILs) have a wide range of current and potential applications, i... more Room temperature ionic liquids (RTILs) have a wide range of current and potential applications, in areas ranging from supercapacitor energy storage to sequestration of toxic gas phase species and use as reusable solvents for selected organic reactions. All these applications stem from their unique physical and chemical properties, which remain understood to only a limited extent. Among the issues of greatest importance is the extent to which RTILs exist as dissociated ionic species and the length scales over which some types of organizations are seen to exist in them. In this Invited Feature Article, we review the current understanding of organization in this family of materials, where opportunities lie in terms of deepening our understanding, and what potential applications would benefit from gaining such knowledge.
The electrochemical properties of a nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C:N) t... more The electrochemical properties of a nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C:N) thin‐film electrode were investigated. Cyclic voltammetry was used to investigate the background current response as a function of potential, scan rate, and electrolyte composition. Cyclic voltammetry and digital simulation were used to determine the heterogeneous electron‐transfer rate constants (ko) for IrCl62−/3−, Fe(CN)63−/4−, ferrocene carboxylic acid, Ru(NH3)63+/2+, and methyl viologen. The results revealed that the background current for the ta‐C:N electrode falls between that of BDD and GC. ko values for all the redox analytes at ta‐C:N were comparable to the values at BDD and GC. ko values were lower for Fe(CN)63−/4−, 10−3 cm s−1, than for the other four redox systems, 10−2–10−1 cm s−1. ko for Ru(NH3)63+/2+ was insensitive to the electrolyte cation (Li+, Na+, K+, and Cs+) at all three electrodes. In contrast, ko for Fe(CN)63−/4− was sensitive to the cation type with the greatest ...
We report on the analytical performance of a tetrahedral amorphous carbon (ta-C:N) thin-film elec... more We report on the analytical performance of a tetrahedral amorphous carbon (ta-C:N) thin-film electrode in flow injection analysis with amperometric detection. Two model redox analytes were used to evaluate the electrode response because of their positive detection potentials and propensity (i.e., reaction products) to adsorb and foul sp(2) carbon electrodes: tyrosine and tryptophan. ta-C:N electrodes are attractive for electroanalytical applications because they possesses many of the excellent properties of boron-doped nanocrystalline diamond (BDD) and they can be deposited at or near room temperature. The results show that the ta-C:N electrode exhibits lower background current and noise than glassy carbon (GC). The electrode was stable microstructurally at the positive potentials used for detection, ∼1.1 V, of these two amino acids and it exhibited superior analytical detection figures of merit as compared to GC and as good or superior to BDD. The linear dynamic range for both anal...
The oxidation reaction mechanism of several aliphatic polyamines was studied using diamond electr... more The oxidation reaction mechanism of several aliphatic polyamines was studied using diamond electrodes with different doping levels and non‐diamond carbon impurity content. The important roles of surface boron and localized non‐diamond carbon sites in the polyamine oxidation reaction mechanism were confirmed. A well defined oxidation peak was seen for all the amines that was dependent on the onset potential for water discharge. Epox shifted negative and the ipox increased with increasing solution pH. ipox also increased with increasing boron doping level or surface boron site density. FIA‐EC analysis revealed a reproducible response for the aliphatic polyamines in a binary solvent (7/93 %) acetonitrile/borate buffer, pH 11.2. Optimum signal‐to‐background ratios for the aliphatic polyamines were seen at potentials between 650 and 670 mV.
Abstract Boron-doped TiO2 (B/TiO2) nano-materials were synthesized by a sol–gel method and charac... more Abstract Boron-doped TiO2 (B/TiO2) nano-materials were synthesized by a sol–gel method and characterized by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrum (FT-IR) and UV–vis diffuse reflectance spectra (DRS). With the test of bacterial inhibition zone, the antibacterial properties of B/TiO2 nano-materials on Escherichia coli were investigated. The results show that the structure of TiO2 could be transformed from amorphous to anatase and then to rutile by increasing calcination temperature; part of the boron atoms probably have been weaved into the interstitial TiO2 structure or incorporated into the TiO2 lattice through occupying O sites, whereas others exist as B2O3. The results of antibacterial experiment under visible light irradiation show that the B/TiO2 nano-materials exhibit enhanced antibacterial efficiency compared with non-doped TiO2. Ultimately, the action mechanism of B/TiO2 doping is discussed.
Diamond thin-film electrodes have gained increased attention in recent years for electroanalysis ... more Diamond thin-film electrodes have gained increased attention in recent years for electroanalysis due to their wide working potential window for aqueous solvents, low background currents and increased signal to background repines as compared to conventional carbon-based electrodes. However, the relationship between the physical, chemical and electronic properties of diamond, and the observed electrochemical performance remains incompletely understood. For polycrystalline films, the electrochemical properties appear to be influenced in a complex manner by various factors which include, (i) the dopant type and concentration (i.e., electronic properties), (ii) morphological features such as grain boundaries, extended and point defects, and (iii) the non-diamond or amorphous carbon impurity content. The applicability of electroanalysis for biogenic amines and amino acids was investigated in alkaline media using cyclic voltammetry, and FIA-EC and LC-EC in the amperometric detection mode. ...
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