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papers from the latest issue:
Green synthesis of sucralose-capped silver nanoparticles for fast colorimetric triethylamine detection
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
In this study, a fast colorimetric triethylamine sensor based on localized surface plasmon resonance of silver nanoparticles is presented. The nanoparticles were synthesized by chemical reduction from silver nitrate using glucose as reducing agent and sucralose as capping agent. The as-synthesized nanoparticles were characterized using UV–vis spectroscopy, X-ray diffraction, transmission electron microscopy and zeta-potential measurements. Their average size was between 4 and 10nm. The suspension of sucralose-capped silver nanoparticles exhibited high stability and very interesting sensor capabilities for a facile and very fast revealing of the presence of triethylamine. It was found that the injection of triethylamine into silver nanoparticles colloidal solution induced immediate enhancement of the yield of the synthesized nanoparticles and their self-aggregation, depending on the concentration of triethylamine and on the reaction time. This fact resulted in naked-eye color change from pale yellow to dark yellow, orange, greenish orange and gray. This simple and quick determination of the presence of triethylamine has possibilities for applying to environmental applications.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
In this study, a fast colorimetric triethylamine sensor based on localized surface plasmon resonance of silver nanoparticles is presented. The nanoparticles were synthesized by chemical reduction from silver nitrate using glucose as reducing agent and sucralose as capping agent. The as-synthesized nanoparticles were characterized using UV–vis spectroscopy, X-ray diffraction, transmission electron microscopy and zeta-potential measurements. Their average size was between 4 and 10nm. The suspension of sucralose-capped silver nanoparticles exhibited high stability and very interesting sensor capabilities for a facile and very fast revealing of the presence of triethylamine. It was found that the injection of triethylamine into silver nanoparticles colloidal solution induced immediate enhancement of the yield of the synthesized nanoparticles and their self-aggregation, depending on the concentration of triethylamine and on the reaction time. This fact resulted in naked-eye color change from pale yellow to dark yellow, orange, greenish orange and gray. This simple and quick determination of the presence of triethylamine has possibilities for applying to environmental applications.
Characterization of an ultrasensitive biosensor based on a nano-Au/DNA/nano-Au/poly(SFR) composite and its application in the simultaneous determination of dopamine, uric acid, guanine, and adenine
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
An ultrasensitive method for the simultaneous determination of dopamine (DA), uric acid (UA), guanine (G), and adenine (A) was developed using differential pulse voltammetry with a three-dimensionally distributed Au nanoparticle (GNP)-modified glassy carbon electrode (GCE). The nano-Au/DNA/nano-Au/poly(SFR)/GCE microstructure was characterized by scanning electron microscopy, electrochemical impedance spectroscopy, and atomic force microscopy, showing an anchored three-dimensional distribution of GNPs on the modified electrode. The electrode exhibited ultrasensitive responses to DA, UA, G, and A due to poly(SFR) electrocatalytic activities and the large surface area of the GNPs. All four analytes showed well-defined catalytic oxidation peaks at the modified electrode. DA, UA, G, and A yielded linear ranges from 8.0×10−9 M to 1.1×10−6 M, 9.0×10−8 M to 1.2×10−5 M, 9.0×10−9 M to 5.0×10−6 M, and 6.0×10−8 M to 8.0×10−7 M, respectively, and detection limits for the analytes were 2.0×10−10 M, 8.0×10−9 M, 5.0×10−10 M, and 4.0×10−9 M, respectively. The feasibility of the proposed assay for use in human serum and urine was investigated and satisfying results were obtained.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
An ultrasensitive method for the simultaneous determination of dopamine (DA), uric acid (UA), guanine (G), and adenine (A) was developed using differential pulse voltammetry with a three-dimensionally distributed Au nanoparticle (GNP)-modified glassy carbon electrode (GCE). The nano-Au/DNA/nano-Au/poly(SFR)/GCE microstructure was characterized by scanning electron microscopy, electrochemical impedance spectroscopy, and atomic force microscopy, showing an anchored three-dimensional distribution of GNPs on the modified electrode. The electrode exhibited ultrasensitive responses to DA, UA, G, and A due to poly(SFR) electrocatalytic activities and the large surface area of the GNPs. All four analytes showed well-defined catalytic oxidation peaks at the modified electrode. DA, UA, G, and A yielded linear ranges from 8.0×10−9 M to 1.1×10−6 M, 9.0×10−8 M to 1.2×10−5 M, 9.0×10−9 M to 5.0×10−6 M, and 6.0×10−8 M to 8.0×10−7 M, respectively, and detection limits for the analytes were 2.0×10−10 M, 8.0×10−9 M, 5.0×10−10 M, and 4.0×10−9 M, respectively. The feasibility of the proposed assay for use in human serum and urine was investigated and satisfying results were obtained.
Graphical abstract
Sensitive and reproducible detection of cardiac troponin I in human plasma using a surface acoustic wave immunosensor
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
We present a sensitive and reproducible surface acoustic wave (SAW) immunosensor that uses an internal reference sensor. A sandwich immunoassay was performed on the working sensing area of the SAW sensor that is able to specifically capture and detect cardiac troponin I (cTnI), while an immunoassay comprising rabbit IgG and anti-rabbit IgG was carried out on the reference sensing area. The analyte in human plasma was captured on gold nanoparticles (AuNPs) that were conjugated in advance with detection antibody. Introduction of these complexes as well as AuNPs conjugated with anti-rabbit IgG into the capture antibody-immobilized working sensor surface and its adjacent rabbit IgG-immobilized reference sensor surface resulted in a classic AuNP-based immunoassay format on both sensing areas. In order to achieve signal enhancement, a gold staining method was performed. Normalized sensor response (a ratio of working sensor response to reference sensor response) due to gold staining varied as a function of applied cTnI concentration. Furthermore, introduction of the internal reference sensor with the normalization technique reduced the coefficient of variation (CV) of the assay by a factor of 4–12, improving reproducibility of the SAW immunosensor. To validate the accuracy of the SAW system, correlation with a commercial system (Centaur®XP, Siemens) was investigated using the plasma of 21 patients and exhibited good agreement with a correlation coefficient (r) of 0.986 and a slope of 0.8 for SAW/Centaur®XP.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
We present a sensitive and reproducible surface acoustic wave (SAW) immunosensor that uses an internal reference sensor. A sandwich immunoassay was performed on the working sensing area of the SAW sensor that is able to specifically capture and detect cardiac troponin I (cTnI), while an immunoassay comprising rabbit IgG and anti-rabbit IgG was carried out on the reference sensing area. The analyte in human plasma was captured on gold nanoparticles (AuNPs) that were conjugated in advance with detection antibody. Introduction of these complexes as well as AuNPs conjugated with anti-rabbit IgG into the capture antibody-immobilized working sensor surface and its adjacent rabbit IgG-immobilized reference sensor surface resulted in a classic AuNP-based immunoassay format on both sensing areas. In order to achieve signal enhancement, a gold staining method was performed. Normalized sensor response (a ratio of working sensor response to reference sensor response) due to gold staining varied as a function of applied cTnI concentration. Furthermore, introduction of the internal reference sensor with the normalization technique reduced the coefficient of variation (CV) of the assay by a factor of 4–12, improving reproducibility of the SAW immunosensor. To validate the accuracy of the SAW system, correlation with a commercial system (Centaur®XP, Siemens) was investigated using the plasma of 21 patients and exhibited good agreement with a correlation coefficient (r) of 0.986 and a slope of 0.8 for SAW/Centaur®XP.
Low cost wireless passive microsensors for the detection of hazardous compounds in water systems for control and monitoring
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
In the present work, we studied the design and fabrication of low cost passive microsensors for measuring hazardous compounds. The sensors were fabricated with low cost and biocompatible materials, making them suitable for several industries and applications. These wireless sensors are small enough to be placed inside pipes and recipients of more than 1cm in diameter. Sensors were tested with air, distilled water, acetic acid, pyridine, N,N-dimethylformamide and butanol, presenting high accuracy, repeatability and reproducibility among substances and sensors. The sensors showed a high resistance to corrosion and oxidation after cycling operation. The whole measuring system, that included the sensor and the coupling antenna, proved to be suitable for measuring low dielectric constant and low volatility compounds presenting an average standard deviations in the detection of any compound of 4.23%.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
In the present work, we studied the design and fabrication of low cost passive microsensors for measuring hazardous compounds. The sensors were fabricated with low cost and biocompatible materials, making them suitable for several industries and applications. These wireless sensors are small enough to be placed inside pipes and recipients of more than 1cm in diameter. Sensors were tested with air, distilled water, acetic acid, pyridine, N,N-dimethylformamide and butanol, presenting high accuracy, repeatability and reproducibility among substances and sensors. The sensors showed a high resistance to corrosion and oxidation after cycling operation. The whole measuring system, that included the sensor and the coupling antenna, proved to be suitable for measuring low dielectric constant and low volatility compounds presenting an average standard deviations in the detection of any compound of 4.23%.
Effect of Sm3+ ion addition on gas sensing properties of Mg1−xCdxFe2O4 system
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
5wt% Sm3+ added nanocrystallite ferrite samples with general formula Mg1−x Cd x Fe2 O4 (x =0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by oxalate co-precipitation method from high purity sulphates. The XRD, SEM and FT-IR techniques were used for characterization of the samples. The XRD confirms cubic spinel structure with orthoferrite (SmFeO3) secondary phase. The crystallite size varies from 28.69 to 32.66nm. The surface morphology SEM study shows increase in grain size with Cd2+ concentration, while it decrease due to Sm3+ addition in Mg–Cd ferrites. The FT-IR spectra show two strong absorption bands in the range of 350–800cm−1. The response decreases with Cd2+ concentration for LPG, Cl2 while increases for C2H5OH. The response of Sm3+ added Mg–Cd ferrite is higher than Mg–Cd ferrite. The response and recovery time of Sm3+ added Mg–Cd ferrites decreases with increase in Cd2+ concentration and lower than Mg–Cd ferrites. The shorter response and recovery time is observed for Sm3+ added Cd ferrite sensor compared to other samples. The response depend on the composition, test gas and grain size of the material.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
5wt% Sm3+ added nanocrystallite ferrite samples with general formula Mg1−x Cd x Fe2 O4 (x =0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by oxalate co-precipitation method from high purity sulphates. The XRD, SEM and FT-IR techniques were used for characterization of the samples. The XRD confirms cubic spinel structure with orthoferrite (SmFeO3) secondary phase. The crystallite size varies from 28.69 to 32.66nm. The surface morphology SEM study shows increase in grain size with Cd2+ concentration, while it decrease due to Sm3+ addition in Mg–Cd ferrites. The FT-IR spectra show two strong absorption bands in the range of 350–800cm−1. The response decreases with Cd2+ concentration for LPG, Cl2 while increases for C2H5OH. The response of Sm3+ added Mg–Cd ferrite is higher than Mg–Cd ferrite. The response and recovery time of Sm3+ added Mg–Cd ferrites decreases with increase in Cd2+ concentration and lower than Mg–Cd ferrites. The shorter response and recovery time is observed for Sm3+ added Cd ferrite sensor compared to other samples. The response depend on the composition, test gas and grain size of the material.
Amperometric biosensor based on polypyrrole and tyrosinase for the detection of tyramine in food samples
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
An electrochemical tyrosinase electrode for detection of tyramine was developed via cross-linking immobilization method over phosphate-doped polypyrrole film. The enzyme tyrosinase immobilized over the polypyrrole thin film preserves well its biocatalytic activity. Tyramine was determined by the direct reduction of biocatalytically formed dopaquinone at −0.250V. The analytical characteristics of this biosensor, including linear range, detection limit, repeatability and storage stability are described. The kinetics of the enzymatic reaction fitted into a Michaelis–Menten type kinetic, as confirmed by the h parameter close to 1 obtained from the Hill's plot. Under the optimum conditions, the current response had a linear relationship with the concentration of tyramine in the range of 4–80×10−6 M, with a sensitivity of 0.1069AM−1 and a limit of detection of 5.7×10−7 M. The biosensor exhibited high repeatability and long term stability. Determination of tyramine in real samples showed good recovery. The selective detection is related to specific action of tyrosinase toward phenolic group from tyramine (1-hydroxy-4-ethylaminobenzene). The developed biosensor was applied to the determination of the tyramine content in sauerkraut samples.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
An electrochemical tyrosinase electrode for detection of tyramine was developed via cross-linking immobilization method over phosphate-doped polypyrrole film. The enzyme tyrosinase immobilized over the polypyrrole thin film preserves well its biocatalytic activity. Tyramine was determined by the direct reduction of biocatalytically formed dopaquinone at −0.250V. The analytical characteristics of this biosensor, including linear range, detection limit, repeatability and storage stability are described. The kinetics of the enzymatic reaction fitted into a Michaelis–Menten type kinetic, as confirmed by the h parameter close to 1 obtained from the Hill's plot. Under the optimum conditions, the current response had a linear relationship with the concentration of tyramine in the range of 4–80×10−6 M, with a sensitivity of 0.1069AM−1 and a limit of detection of 5.7×10−7 M. The biosensor exhibited high repeatability and long term stability. Determination of tyramine in real samples showed good recovery. The selective detection is related to specific action of tyrosinase toward phenolic group from tyramine (1-hydroxy-4-ethylaminobenzene). The developed biosensor was applied to the determination of the tyramine content in sauerkraut samples.
Polymeric cantilever sensors functionalized with multiamine supramolecular hydrogel
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
This paper presents a multiamine supramolecular hydrogel (SH) modified SU-8 cantilever sensor. A chemical process to integrate the SH on the surface of SU-8 cantilever is developed to improve the stability and reusability of the functionalized cantilever sensor, instead of physical surface functionalization methods such as direct coating and self-assembly. The network structure of the SH is formed through a ring-opening and amine-substituted reaction in epoxy groups of the SU-8. The surface functionalization of the SU-8 cantilever is characterized by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The modified SU-8 cantilever sensor has been successfully applied for real-time measurement of metal ions concentration in aqueous solutions. Responses from the cantilever due to surface stress are induced by the axial coordination of ferric ions to amino groups of the SH and the chemical energy is converted into the mechanical energy which can be measured by a piezoresistive sensor. The concentration-dependent performance of the sensor is demonstrated and discussed, indicating a potential use of SH functionalized cantilever sensors.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
This paper presents a multiamine supramolecular hydrogel (SH) modified SU-8 cantilever sensor. A chemical process to integrate the SH on the surface of SU-8 cantilever is developed to improve the stability and reusability of the functionalized cantilever sensor, instead of physical surface functionalization methods such as direct coating and self-assembly. The network structure of the SH is formed through a ring-opening and amine-substituted reaction in epoxy groups of the SU-8. The surface functionalization of the SU-8 cantilever is characterized by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The modified SU-8 cantilever sensor has been successfully applied for real-time measurement of metal ions concentration in aqueous solutions. Responses from the cantilever due to surface stress are induced by the axial coordination of ferric ions to amino groups of the SH and the chemical energy is converted into the mechanical energy which can be measured by a piezoresistive sensor. The concentration-dependent performance of the sensor is demonstrated and discussed, indicating a potential use of SH functionalized cantilever sensors.
Hollow, porous, and yttrium functionalized ZnO nanospheres with enhanced gas-sensing performances
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
We report the synthesis of a hierarchical nanostructure of hollow and porous ZnO nanospheres with a high specific surface area as a novel sensing material to toxic formaldehyde by a simple template-free hydrothermal technique in organic solution. We demonstrate that the liquid mixture ratio and hydrothermal time play a pivotal role in forming such unique morphology and propose a growth mechanism of Ostwald ripening coupled with grain rotation induced grain coalescence. Comparison investigations reveal that yttrium allows resistance reduction of sensors and enhances significantly gas-sensing performances of ZnO nanospheres toward the formaldehyde over the commonly used undecorated ZnO nanoparticles. Such hollow, porous, and yttrium functionalized ZnO nanospheres could therefore serve as hybrid functional materials for chemical gas sensors. The results represent an advance of hierarchical nanostructures in enhancing further the functionality of gas sensors, and the facile method presented could be applicable to many other sensing materials.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
We report the synthesis of a hierarchical nanostructure of hollow and porous ZnO nanospheres with a high specific surface area as a novel sensing material to toxic formaldehyde by a simple template-free hydrothermal technique in organic solution. We demonstrate that the liquid mixture ratio and hydrothermal time play a pivotal role in forming such unique morphology and propose a growth mechanism of Ostwald ripening coupled with grain rotation induced grain coalescence. Comparison investigations reveal that yttrium allows resistance reduction of sensors and enhances significantly gas-sensing performances of ZnO nanospheres toward the formaldehyde over the commonly used undecorated ZnO nanoparticles. Such hollow, porous, and yttrium functionalized ZnO nanospheres could therefore serve as hybrid functional materials for chemical gas sensors. The results represent an advance of hierarchical nanostructures in enhancing further the functionality of gas sensors, and the facile method presented could be applicable to many other sensing materials.
Cell electrofusion in microfluidic devices: A review
06 February 2013,
08:24:53
1 March 2013
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
Cell electrofusion in microfluidic devices attracted great attention in recent years due to its widespread applications potential in cell-based studies. In these microfluidic devices, many manipulation methods, such as chemical conjugation, electric field induced dielectrophoresis, and microfluidic controlling based on microstructure, are used to improve the pairing precision of cells, especially heterogeneous cells. High-strength electric field can produce minipores on cell membrane and induce cell fusion. It can be generated by a constricting electric field with microstructures or two microelectrodes. In comparison with the traditional electrofusion or other cell-fusion methods, microfluidic cell-electrofusion method has many advantages such as precise manipulation, high efficiency in cell pairing and fusion, higher cell viability, lower sample contamination and smaller Joule heating effect. In this article, the development of various microfluidic cell-electrofusion methods is reviewed. Some important parameters affecting the cell electrofusion are discussed in detail. Techniques that can be integrated on microfluidic devices for high-efficiency cell electrofusion, such as on-chip cell separation and culture, are also discussed comprehensively.
Publication year: 2013
Source:Sensors and Actuators B: Chemical, Volume 178
Cell electrofusion in microfluidic devices attracted great attention in recent years due to its widespread applications potential in cell-based studies. In these microfluidic devices, many manipulation methods, such as chemical conjugation, electric field induced dielectrophoresis, and microfluidic controlling based on microstructure, are used to improve the pairing precision of cells, especially heterogeneous cells. High-strength electric field can produce minipores on cell membrane and induce cell fusion. It can be generated by a constricting electric field with microstructures or two microelectrodes. In comparison with the traditional electrofusion or other cell-fusion methods, microfluidic cell-electrofusion method has many advantages such as precise manipulation, high efficiency in cell pairing and fusion, higher cell viability, lower sample contamination and smaller Joule heating effect. In this article, the development of various microfluidic cell-electrofusion methods is reviewed. Some important parameters affecting the cell electrofusion are discussed in detail. Techniques that can be integrated on microfluidic devices for high-efficiency cell electrofusion, such as on-chip cell separation and culture, are also discussed comprehensively.
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