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Papers from the latest issue:
Application of displacement principle for detecting heavy metal ions and EDTA using microcantilevers
29 October 2011, 21:36:49
Publication year: 2011
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
X. Chen, W. Chen, A. Mulchandani, U. Mohideen
A microcantilever sensor based on a reversible displacement reaction was developed. The demonstration was performed with the Ni-NTA-EDTA sample system. Ni ions, a typical heavy metal, were injected and adsorbed onto a NTA-functionalized AFM cantilever in a fluid cell. This adsorption resulted in tensile stress which was detected by monitoring the corresponding deflection of the microcantilever. In the next step, EDTA was injected into the cell to release the adsorbed Ni ions from the surface of the cantilever. Since EDTA molecules have a stronger affinity for Ni ions compared to NTA, they compete with and eventually replace the NTA molecules and take over the binding positions on Ni. The displacement of Ni ions from the cantilever by EDTA, followed by water flow removes the tensile stress and restores the cantilever deflection to its original value. In this way, both heavy metal ions and EDTA can be specifically recognized. From the cantilever deflection, the concentration of Ni ions and EDTA can be quantified. The detection limits are presently at the micromolar level. Another weaker Ni ion binder, imidazole, was unable to dissociate Ni ions from NTA and produce similar effects. The demonstrated principle can be used for microcantilever sensors which are capable of regeneration for multiple uses. The method presented can be generalized to detect other reactants.
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
X. Chen, W. Chen, A. Mulchandani, U. Mohideen
A microcantilever sensor based on a reversible displacement reaction was developed. The demonstration was performed with the Ni-NTA-EDTA sample system. Ni ions, a typical heavy metal, were injected and adsorbed onto a NTA-functionalized AFM cantilever in a fluid cell. This adsorption resulted in tensile stress which was detected by monitoring the corresponding deflection of the microcantilever. In the next step, EDTA was injected into the cell to release the adsorbed Ni ions from the surface of the cantilever. Since EDTA molecules have a stronger affinity for Ni ions compared to NTA, they compete with and eventually replace the NTA molecules and take over the binding positions on Ni. The displacement of Ni ions from the cantilever by EDTA, followed by water flow removes the tensile stress and restores the cantilever deflection to its original value. In this way, both heavy metal ions and EDTA can be specifically recognized. From the cantilever deflection, the concentration of Ni ions and EDTA can be quantified. The detection limits are presently at the micromolar level. Another weaker Ni ion binder, imidazole, was unable to dissociate Ni ions from NTA and produce similar effects. The demonstrated principle can be used for microcantilever sensors which are capable of regeneration for multiple uses. The method presented can be generalized to detect other reactants.
Development of a high sensitive automatic setup for screening of microcystins in surface waters by employing a LED-based photometric detector
29 October 2011, 21:36:49
Publication year: 2011
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
Gláucia P. Vieira, Sheila R.W. Perdigão, Marli F. Fiore, Boaventura F. Reis
In this manuscript, an automatic setup for screening of microcystins in surface waters by employing photometric detection is described. Microcystins are toxins delivered by cyanobacteria within an aquatic environment, which have been considered strongly poisonous for humans. For that reason, the World Health Organization (WHO) has proposed a provisional guideline value for drinking water of 1 μgL. In this work, we developed an automated equipment setup, which allows the screening of water for concentration of microcystins below 0.1 μgL. The photometric method was based on the enzyme-linked immunosorbent assay (ELISA) and the analytical signal was monitored at 458 nm using a homemade LED-based photometer. The proposed system was employed for the detection of microcystins in rivers and lakes waters. Accuracy was assessed by processing samples using a reference method and applying the pairedt-test between results. No significant difference at the 95% confidence level was observed. Other useful features including a linear response ranging from 0.05 up to 2.00 μgL(R = 0.999) and a detection limit of 0.03 μgLmicrocystins were achieved.
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
Gláucia P. Vieira, Sheila R.W. Perdigão, Marli F. Fiore, Boaventura F. Reis
In this manuscript, an automatic setup for screening of microcystins in surface waters by employing photometric detection is described. Microcystins are toxins delivered by cyanobacteria within an aquatic environment, which have been considered strongly poisonous for humans. For that reason, the World Health Organization (WHO) has proposed a provisional guideline value for drinking water of 1 μgL. In this work, we developed an automated equipment setup, which allows the screening of water for concentration of microcystins below 0.1 μgL. The photometric method was based on the enzyme-linked immunosorbent assay (ELISA) and the analytical signal was monitored at 458 nm using a homemade LED-based photometer. The proposed system was employed for the detection of microcystins in rivers and lakes waters. Accuracy was assessed by processing samples using a reference method and applying the pairedt-test between results. No significant difference at the 95% confidence level was observed. Other useful features including a linear response ranging from 0.05 up to 2.00 μgL(R = 0.999) and a detection limit of 0.03 μgLmicrocystins were achieved.
Important considerations for effective gas sensors based on metal oxide nanoneedles films
29 October 2011, 21:36:49
Publication year: 2011
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
T. Stoycheva, S. Vallejos, C. Blackman, S.J.A. Moniz, J. Calderer, ...
Gas sensor devices based on either polycrystalline or nanoneedle tungsten oxide were depositedin situon classical ceramic substratesviaAACVD, and subsequently functionalised with gold nanoparticlesviasputtering. The sensing properties of the films were tested to a wide range of analytes, revealing highresponsesto ethanol, hydrogen, and nitrogen dioxide, at low operating temperatures (≤ 250 °C),and a lack of response to carbon monoxide, ammonia, and hydrogen sulfide. In addition, thesensing responsesto hydrogen and nitrogen dioxide, at 100 °C and 150 °C, were improved by using gold functionalised structures. Modest differences of the sensor response magnitude in polycrystalline, and nanoneedle films were observed, suggesting the need of special substrate platforms for effective application of nanostructured films in gas sensors devices.
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
T. Stoycheva, S. Vallejos, C. Blackman, S.J.A. Moniz, J. Calderer, ...
Gas sensor devices based on either polycrystalline or nanoneedle tungsten oxide were depositedin situon classical ceramic substratesviaAACVD, and subsequently functionalised with gold nanoparticlesviasputtering. The sensing properties of the films were tested to a wide range of analytes, revealing highresponsesto ethanol, hydrogen, and nitrogen dioxide, at low operating temperatures (≤ 250 °C),and a lack of response to carbon monoxide, ammonia, and hydrogen sulfide. In addition, thesensing responsesto hydrogen and nitrogen dioxide, at 100 °C and 150 °C, were improved by using gold functionalised structures. Modest differences of the sensor response magnitude in polycrystalline, and nanoneedle films were observed, suggesting the need of special substrate platforms for effective application of nanostructured films in gas sensors devices.
Single-walled carbon nanotube-magnetite nanoparticles film modified ferrule graphite electrode for voltammetric determination of 2-Diisopropylaminoethanethiol
29 October 2011, 21:36:49
Publication year: 2011
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
S.P. Sharma, M. Farrukh, A. Chaturvedi, A.R. Srivastava, M.V.S. Suryanarayana, ...
An electrochemical sensor based on single-walled carbon nanotube-magnetite nanoparticles (SWCNT-nFe3O4) film for the voltammetric determination of 2-diisopropylaminoethanethiol (DIPAET) is described here. The electrochemical behavior of DIPAET at the SWCNT-nFe3O4film modified ferrule graphite electrode (FGE) was investigated by cyclic voltammetry. DIPAET exhibited enhanced voltammetric response at SWCNT-nFe3O4modified FGE. This electrochemical sensor shows a favorable analytical performance for DIPAET detection with a detection limit (S/N = 1.4) of 1.41 × 10 M, high sensitivity of 53.05 μAnMand electron transfer rate constant of ∼7.22 s. Moreover, DIPAET can be detected in dynamic range of 0.5–4 μg/L with inherent linearity (R = 0.96627)
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
S.P. Sharma, M. Farrukh, A. Chaturvedi, A.R. Srivastava, M.V.S. Suryanarayana, ...
An electrochemical sensor based on single-walled carbon nanotube-magnetite nanoparticles (SWCNT-nFe3O4) film for the voltammetric determination of 2-diisopropylaminoethanethiol (DIPAET) is described here. The electrochemical behavior of DIPAET at the SWCNT-nFe3O4film modified ferrule graphite electrode (FGE) was investigated by cyclic voltammetry. DIPAET exhibited enhanced voltammetric response at SWCNT-nFe3O4modified FGE. This electrochemical sensor shows a favorable analytical performance for DIPAET detection with a detection limit (S/N = 1.4) of 1.41 × 10 M, high sensitivity of 53.05 μAnMand electron transfer rate constant of ∼7.22 s. Moreover, DIPAET can be detected in dynamic range of 0.5–4 μg/L with inherent linearity (R = 0.96627)
A Magnetic Resonance Imaging Nanosensor for Hg (II) Based on Thymidine-Functionalized Supermagnetic Iron Oxide Nanoparticles
29 October 2011, 21:36:49
Publication year: 2011
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
Hong Yang, Zhiqing Tian, Juanjuan Wang, Shiping Yang
A MRI nanosensor for Hg (II) was developed based on superparamagnetic iron oxide nanoparticles (SPIO NPs). The detection mechanism is attributed to Hg (II)-induced the nanoassembly of thymidine-functionalized SPIO NPs from a dispersed to an aggregated state with a corresponding decrease in the transverse relaxation time (T2) of adjacent water protons. Furthermore, an enhancement of transverse relaxation rates (1/T2) showed the high selectivity for Hg (II) compared with other transition and main group metal ions.
Source: Sensors and Actuators B: Chemical, Available online 29 October 2011
Hong Yang, Zhiqing Tian, Juanjuan Wang, Shiping Yang
A MRI nanosensor for Hg (II) was developed based on superparamagnetic iron oxide nanoparticles (SPIO NPs). The detection mechanism is attributed to Hg (II)-induced the nanoassembly of thymidine-functionalized SPIO NPs from a dispersed to an aggregated state with a corresponding decrease in the transverse relaxation time (T2) of adjacent water protons. Furthermore, an enhancement of transverse relaxation rates (1/T2) showed the high selectivity for Hg (II) compared with other transition and main group metal ions.
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