A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Selected
papers from the latest issue:
Fabrication of a Au@SnO2 core–shell structure for gaseous formaldehyde sensing at room temperature
13 September 2013,
09:00:36
Publication date: January
2014
Source:Sensors and Actuators B: Chemical, Volume 190
Author(s): Feng-Chao Chung , Ren-Jang Wu , Fu-Chou Cheng
This paper describes the fabrication of a Au@SnO2 core–shell structure using the sol gel method to manufacture the sensing materials. The properties of the sensing material were analyzed with UV–vis spectra, Fourier transform infrared spectroscopy, and transmission electron microscopy. The SnO2 material showed no response, whereas 1wt% Au/SnO2 exhibited a 2.4 sensor response. The response t 90 (for a result equaling 90% of the equilibrium signal) and recovery t r90 (to adjust the signal to 90% background signal) times of the 1wt% Au/SnO2 material measured 240s and 210s, respectively. Au@SnO2 further enhanced the sensor response to 2.9 while reducing the response and recovery times to 80s and 62s. This study also demonstrates a formaldehyde gas-sensing mechanism involving HCHO adsorption and surface reaction and product desorption.
Source:Sensors and Actuators B: Chemical, Volume 190
Author(s): Feng-Chao Chung , Ren-Jang Wu , Fu-Chou Cheng
This paper describes the fabrication of a Au@SnO2 core–shell structure using the sol gel method to manufacture the sensing materials. The properties of the sensing material were analyzed with UV–vis spectra, Fourier transform infrared spectroscopy, and transmission electron microscopy. The SnO2 material showed no response, whereas 1wt% Au/SnO2 exhibited a 2.4 sensor response. The response t 90 (for a result equaling 90% of the equilibrium signal) and recovery t r90 (to adjust the signal to 90% background signal) times of the 1wt% Au/SnO2 material measured 240s and 210s, respectively. Au@SnO2 further enhanced the sensor response to 2.9 while reducing the response and recovery times to 80s and 62s. This study also demonstrates a formaldehyde gas-sensing mechanism involving HCHO adsorption and surface reaction and product desorption.
Theoretical and experimental study of the response of CuO gas sensor under ozone
13 September 2013,
09:00:36
Publication date: January
2014
Source:Sensors and Actuators B: Chemical, Volume 190
Author(s): A. Bejaoui , J. Guerin , J.A. Zapien , K. Aguir
In this paper, we assumed that the ozone detection mechanism of p-type semiconductor resistive gas sensors in dry air is essentially due to adsorption of species O2, O2 −, O and O− at the surface of the grains. Based on the Wolkenstein adsorption theory, a dynamic model was formulated taking into account the chemical interactions between the sensor and chemisorbed species and the conduction mechanism. The present model predicts the coverage degree and sensor response as a function of characteristic properties of the semiconductor: grain size, working temperature and ozone concentrations. The simulation results are compared with the experimental data obtained with a CuO based sensor made in our laboratory and the correlation between simulated and experiments results is quite good.
Source:Sensors and Actuators B: Chemical, Volume 190
Author(s): A. Bejaoui , J. Guerin , J.A. Zapien , K. Aguir
In this paper, we assumed that the ozone detection mechanism of p-type semiconductor resistive gas sensors in dry air is essentially due to adsorption of species O2, O2 −, O and O− at the surface of the grains. Based on the Wolkenstein adsorption theory, a dynamic model was formulated taking into account the chemical interactions between the sensor and chemisorbed species and the conduction mechanism. The present model predicts the coverage degree and sensor response as a function of characteristic properties of the semiconductor: grain size, working temperature and ozone concentrations. The simulation results are compared with the experimental data obtained with a CuO based sensor made in our laboratory and the correlation between simulated and experiments results is quite good.
Robust identification of bacteria based on repeated odor measurements from individual bacteria colonies
13 September 2013,
09:00:36
Publication date: January
2014
Source:Sensors and Actuators B: Chemical, Volume 190
Author(s): Geoffrey C. Green , Adrian D.C. Chan , Min Lin
Conventional methods of food safety testing for bacterial pathogens are accurate, but require long processing times (up to a week) to return an unequivocal determination of the presence and nature of contaminant bacteria. Biosensor-based methods, including the electronic nose (e-nose) are being researched as alternative approaches. In this paper, we present a measurement system capable of evaluating the reliability of e-nose based bacteria identification, at the genus level, based on single colonies of bacteria. Confidence measures are incorporated, which provide the user with information allowing them to better assess the reliability of any individual classification result. The system is tested with four non-pathogenic bacteria types (two from the same species, Escherichia coli). The results demonstrated classification accuracies greater than 80%. Furthermore, it is shown that higher classification accuracy (96.7%) can be achieved by repeated e-nose sampling of the same colony and using all available odor responses to characterize a sample. Single bacterial colonies are available relatively early during the conventional testing process, so further developments in this area hold the potential to shorten the testing times, thereby complementing existing methods of food pathogen testing.
Source:Sensors and Actuators B: Chemical, Volume 190
Author(s): Geoffrey C. Green , Adrian D.C. Chan , Min Lin
Conventional methods of food safety testing for bacterial pathogens are accurate, but require long processing times (up to a week) to return an unequivocal determination of the presence and nature of contaminant bacteria. Biosensor-based methods, including the electronic nose (e-nose) are being researched as alternative approaches. In this paper, we present a measurement system capable of evaluating the reliability of e-nose based bacteria identification, at the genus level, based on single colonies of bacteria. Confidence measures are incorporated, which provide the user with information allowing them to better assess the reliability of any individual classification result. The system is tested with four non-pathogenic bacteria types (two from the same species, Escherichia coli). The results demonstrated classification accuracies greater than 80%. Furthermore, it is shown that higher classification accuracy (96.7%) can be achieved by repeated e-nose sampling of the same colony and using all available odor responses to characterize a sample. Single bacterial colonies are available relatively early during the conventional testing process, so further developments in this area hold the potential to shorten the testing times, thereby complementing existing methods of food pathogen testing.
A fluorescent colorimetric pH sensor and the influences of matrices on sensing performances
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Yanqing Tian , Emily Fuller , Summer Klug , Fred Lee , Fengyu Su , Liqiang Zhang , Shih-hui Chao , Deirdre R. Meldrum
A fluorescent colorimetric pH sensor was developed by a polymerization of a monomeric fluorescein based green emitter (SM1) with a monomeric 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran derived red emitter (SM2) in poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (PHEMA-co-PAM) matrices. Polymerized SM1 (PSM1) in the polymer matrices showed bright emissions at basic conditions and weak emissions at acidic conditions. Polymerized SM2 (PSM2) in the polymer matrices exhibited a vastly different response when compared to PSM1. The emissions of PSM2 are stronger under acidic conditions than those under basic conditions. When SM1 and SM2 were polymerized in the same polymer matrix, a dual emission sensor acting as a ratiometric pH sensor (PSM1,2) was successfully developed. Because the PSM1 and PSM2 exhibited different pH responses and separated emission windows, the changes in the emission colors were clearly observed in their dual color sensor of PSM1,2, which changed emission colors dramatically from green at pH 7 to red at pH 4, which was detected visually and/or by using a color camera under an excitation of 488nm. In addition to the development of the dual color ratiometric pH sensor, we also studied the effects of different matrix compositions, crosslinkers, and charges on the reporting capabilities of the sensors (sensitivity and pK a).
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Yanqing Tian , Emily Fuller , Summer Klug , Fred Lee , Fengyu Su , Liqiang Zhang , Shih-hui Chao , Deirdre R. Meldrum
A fluorescent colorimetric pH sensor was developed by a polymerization of a monomeric fluorescein based green emitter (SM1) with a monomeric 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran derived red emitter (SM2) in poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (PHEMA-co-PAM) matrices. Polymerized SM1 (PSM1) in the polymer matrices showed bright emissions at basic conditions and weak emissions at acidic conditions. Polymerized SM2 (PSM2) in the polymer matrices exhibited a vastly different response when compared to PSM1. The emissions of PSM2 are stronger under acidic conditions than those under basic conditions. When SM1 and SM2 were polymerized in the same polymer matrix, a dual emission sensor acting as a ratiometric pH sensor (PSM1,2) was successfully developed. Because the PSM1 and PSM2 exhibited different pH responses and separated emission windows, the changes in the emission colors were clearly observed in their dual color sensor of PSM1,2, which changed emission colors dramatically from green at pH 7 to red at pH 4, which was detected visually and/or by using a color camera under an excitation of 488nm. In addition to the development of the dual color ratiometric pH sensor, we also studied the effects of different matrix compositions, crosslinkers, and charges on the reporting capabilities of the sensors (sensitivity and pK a).
AC electro-osmotic micromixer using a face-to-face, asymmetric pair of planar electrodes
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Jhih-Lin Chen , Wei-Hung Shih , Wen-Hsin Hsieh
This paper is the first to report the mixing performance of an AC electro-osmotic (AC-EO) micromixer based on the two sets of vortices generated by a face-to-face, asymmetric pair of planar electrodes. The larger top electrode of the asymmetric electrode pair was rectangular (30×60mm2) and the much smaller bottom electrode was also rectangular (500×700μm2) and featured two protrusions. Due to the highly three-dimensional flow pattern generated by the unique shape of the face-to-face electrode pair, the mixing enhancement factor (mixing time by diffusion/mixing time by the micromixer) exhibited by the reported micromixer ranged from 290 to 360 and the mixing performance values were uniform across the entire height of the fluid cavity. The usefulness of the mixer in hybridizing single-stranded deoxyribonucleic acids and mixing Escherichia coli with RNA stains was also demonstrated experimentally. A numerical investigation was conducted to study the three-dimensional AC-EO flow patterns induced by the face-to-face, asymmetric electrode pair. This analysis made it possible to identify a detailed flow pattern and the formation mechanism of the vortices. The confluence of inward AC-EO flows from the edges of the bottom-electrode protrusion locally induced a large inward-pumping force and was responsible for the formation of the four vortices at the four corners of the bottom electrode. The numerical and experimental results of this research provide information that will be useful in future applications and research in the area of microfluidic manipulation.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Jhih-Lin Chen , Wei-Hung Shih , Wen-Hsin Hsieh
This paper is the first to report the mixing performance of an AC electro-osmotic (AC-EO) micromixer based on the two sets of vortices generated by a face-to-face, asymmetric pair of planar electrodes. The larger top electrode of the asymmetric electrode pair was rectangular (30×60mm2) and the much smaller bottom electrode was also rectangular (500×700μm2) and featured two protrusions. Due to the highly three-dimensional flow pattern generated by the unique shape of the face-to-face electrode pair, the mixing enhancement factor (mixing time by diffusion/mixing time by the micromixer) exhibited by the reported micromixer ranged from 290 to 360 and the mixing performance values were uniform across the entire height of the fluid cavity. The usefulness of the mixer in hybridizing single-stranded deoxyribonucleic acids and mixing Escherichia coli with RNA stains was also demonstrated experimentally. A numerical investigation was conducted to study the three-dimensional AC-EO flow patterns induced by the face-to-face, asymmetric electrode pair. This analysis made it possible to identify a detailed flow pattern and the formation mechanism of the vortices. The confluence of inward AC-EO flows from the edges of the bottom-electrode protrusion locally induced a large inward-pumping force and was responsible for the formation of the four vortices at the four corners of the bottom electrode. The numerical and experimental results of this research provide information that will be useful in future applications and research in the area of microfluidic manipulation.
A fluidic bridge based MEMS paramagnetic oxygen sensor
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Stefan Vonderschmidt , Jörg Müller
This paper describes a new paramagnetic oxygen sensor based on the combination of a fluidic and an electric bridge fabricated in MEMS technology. In the sensor the gas mixture to be analysed is injected across an unguided flow section, where it is subjected to an in-plane magnetic field gradient, originating from a small permanent magnet placed at the side, followed by three parallel channels. The channel arrangement consists of a centre channel, guiding an undisturbed flow, a measurement channel close to the magnet and a reference channel on the opposite side of the centre channel. The sensor principle relies on the attraction of the paramagnetic oxygen into the measurement channel by the high strength magnetic field and corresponding distraction from both, the main and the reference channel. The change in flow is measured via integrated thermoanemometers.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Stefan Vonderschmidt , Jörg Müller
This paper describes a new paramagnetic oxygen sensor based on the combination of a fluidic and an electric bridge fabricated in MEMS technology. In the sensor the gas mixture to be analysed is injected across an unguided flow section, where it is subjected to an in-plane magnetic field gradient, originating from a small permanent magnet placed at the side, followed by three parallel channels. The channel arrangement consists of a centre channel, guiding an undisturbed flow, a measurement channel close to the magnet and a reference channel on the opposite side of the centre channel. The sensor principle relies on the attraction of the paramagnetic oxygen into the measurement channel by the high strength magnetic field and corresponding distraction from both, the main and the reference channel. The change in flow is measured via integrated thermoanemometers.
Modification of a QCN sensor by SiO2 nanoparticles and MIP for telone determination: Improving its selectivity and sensitivity
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): A. Mirmohseni , M. Rastgouy-Houjaghan
A quartz crystal nanobalance (QCN) sensor was developed for the selective determination of telone in aqueous solutions. Telone imprinted nanocomposite was synthesized using SiO2 nanopowders and acrylic acid. FTIR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were employed to characterize the morphology and microstructure of the SiO2-MIP nanocomposite. The prepared SiO2-MIP nanocomposite particles were coated on quartz crystal electrode to form complementary structures for the template recognition of telone. The SiO2-MIP coated electrode was used to determine telone levels in solution. The developed sensor demonstrated a high selectivity and sensitivity (4.96Hz per mgL−1) for telone. It can also be used for telone determination in the concentration range between 1 to 40mgL−1. Furthermore, a good reproducibility, R.S.D.=1.66% (n =5) was observed. During its photocatalytic degradation by UV/ZnO, telone residue process was measured by the developed sensor and GC to validate the accuracy of the developed sensor in real world situation. According to the results of the t-test, QCN sensor and GC spectroscopy measurement results enjoy good agreement. Therefore, a fabricated sensing system has the potential for real sample application.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): A. Mirmohseni , M. Rastgouy-Houjaghan
A quartz crystal nanobalance (QCN) sensor was developed for the selective determination of telone in aqueous solutions. Telone imprinted nanocomposite was synthesized using SiO2 nanopowders and acrylic acid. FTIR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were employed to characterize the morphology and microstructure of the SiO2-MIP nanocomposite. The prepared SiO2-MIP nanocomposite particles were coated on quartz crystal electrode to form complementary structures for the template recognition of telone. The SiO2-MIP coated electrode was used to determine telone levels in solution. The developed sensor demonstrated a high selectivity and sensitivity (4.96Hz per mgL−1) for telone. It can also be used for telone determination in the concentration range between 1 to 40mgL−1. Furthermore, a good reproducibility, R.S.D.=1.66% (n =5) was observed. During its photocatalytic degradation by UV/ZnO, telone residue process was measured by the developed sensor and GC to validate the accuracy of the developed sensor in real world situation. According to the results of the t-test, QCN sensor and GC spectroscopy measurement results enjoy good agreement. Therefore, a fabricated sensing system has the potential for real sample application.
Slime mould tactile sensor
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Andrew Adamatzky
Slime mould Physarum polycephalum is a single cells visible by unaided eye. The cells shows a wide spectrum of intelligent behaviour. By interpreting the behaviour in terms of computation one can make a slime mould based computing device. The Physarum computers are capable to solve a range of tasks of computational geometry, optimisation and logic. Physarum computers designed so far lack of localised inputs. Commonly used inputs — illumination and chemo-attractants and -repellents — usually act on extended domains of the slime mould's body. Aiming to design massive-parallel tactile inputs for slime mould computers we analyse a temporal dynamic of P. polycephalum's electrical response to tactile stimulation. In experimental laboratory studies we discover how the Physarum responds to application and removal of a local mechanical pressure with electrical potential impulses and changes in its electrical potential oscillation patterns.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Andrew Adamatzky
Slime mould Physarum polycephalum is a single cells visible by unaided eye. The cells shows a wide spectrum of intelligent behaviour. By interpreting the behaviour in terms of computation one can make a slime mould based computing device. The Physarum computers are capable to solve a range of tasks of computational geometry, optimisation and logic. Physarum computers designed so far lack of localised inputs. Commonly used inputs — illumination and chemo-attractants and -repellents — usually act on extended domains of the slime mould's body. Aiming to design massive-parallel tactile inputs for slime mould computers we analyse a temporal dynamic of P. polycephalum's electrical response to tactile stimulation. In experimental laboratory studies we discover how the Physarum responds to application and removal of a local mechanical pressure with electrical potential impulses and changes in its electrical potential oscillation patterns.
Highly sensitive gallia-SnO2 nanocomposite sensors to CO and ethanol in presence of methane
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Minoo Bagheri , Abbas Ali Khodadadi , Ali Reza Mahjoub , Yadollah Mortazavi
Responses of gallia-SnO2 nanocomposite sensors, containing 0–50wt% Ga2O3 calcined at 500–850°C, to CO, methane and ethanol are investigated. The gallia-SnO2 samples were prepared via a facile co-precipitation method using stannic chloride and gallium nitrate aqueous solutions without any template and characterized by XRD, EDX, TEM, PL and BET surface area techniques. The samples containing up to 25wt% gallia and calcined at 500°C indicate that only tetragonal rutile structure of SnO2 is formed. The Ga4SnO8 and β-Ga2O3 phases are observed for the samples containing 50wt% Ga2O3 and calcined at 850 and 1050°C, respectively. The average particle sizes of the nanocomposites gradually decrease from 21.6 to 6.7nm, as their gallia contents increase from 0 to 25wt%. The highest responses of 315 and 119 are observed for 300ppm CO and ethanol by the sensors containing 5 and 1wt% Ga2O3, respectively. The sensors containing 25wt% Ga2O3 calcined at 850°C and 50wt% gallia calcined at 500 and 850°C are selective to CO and show negligible responses to ethanol and methane.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Minoo Bagheri , Abbas Ali Khodadadi , Ali Reza Mahjoub , Yadollah Mortazavi
Responses of gallia-SnO2 nanocomposite sensors, containing 0–50wt% Ga2O3 calcined at 500–850°C, to CO, methane and ethanol are investigated. The gallia-SnO2 samples were prepared via a facile co-precipitation method using stannic chloride and gallium nitrate aqueous solutions without any template and characterized by XRD, EDX, TEM, PL and BET surface area techniques. The samples containing up to 25wt% gallia and calcined at 500°C indicate that only tetragonal rutile structure of SnO2 is formed. The Ga4SnO8 and β-Ga2O3 phases are observed for the samples containing 50wt% Ga2O3 and calcined at 850 and 1050°C, respectively. The average particle sizes of the nanocomposites gradually decrease from 21.6 to 6.7nm, as their gallia contents increase from 0 to 25wt%. The highest responses of 315 and 119 are observed for 300ppm CO and ethanol by the sensors containing 5 and 1wt% Ga2O3, respectively. The sensors containing 25wt% Ga2O3 calcined at 850°C and 50wt% gallia calcined at 500 and 850°C are selective to CO and show negligible responses to ethanol and methane.
A promising gold nanocluster fluorescent sensor for the highly sensitive and selective detection of S2−
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Ma-Lin Cui , Jia-Ming Liu , Xin-Xing Wang , Li-Ping Lin , Li Jiao , Zhi-Yong Zheng , Li-Hong Zhang , Shu-Lian Jiang
Bright red-emissive gold nanoclusters (AuNCs) were synthesized by a facile one-pot approach in aqueous solution using bovine serum albumin (BSA) as a protecting agent. A new BSA-AuNC fluorescent sensor for the detection of S2− has been designed based on the sharp fluorescence quenching of BSA-AuNCs, which results from the degradation of its structure due to the formation of Au2S by the reaction between Au and S2−. The proposed highly sensitive (the detection limit [LD] was 0.029μM) and selective sensor was applied to the detection of S2− in the presence of high concentrations of different anions in aqueous solution, and the results were in good agreement with those determined by electrochemical methods. The sensor is shown to be environmentally friendly, simple, responsive and practical. Meanwhile, the morphological changes of BSA-AuNCs and BSA-AuNCs-S2− were characterized by high-resolution transmission electron microscopy (HRTEM). Furthermore, the sensing mechanism for the detection of S2− is discussed.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Ma-Lin Cui , Jia-Ming Liu , Xin-Xing Wang , Li-Ping Lin , Li Jiao , Zhi-Yong Zheng , Li-Hong Zhang , Shu-Lian Jiang
Bright red-emissive gold nanoclusters (AuNCs) were synthesized by a facile one-pot approach in aqueous solution using bovine serum albumin (BSA) as a protecting agent. A new BSA-AuNC fluorescent sensor for the detection of S2− has been designed based on the sharp fluorescence quenching of BSA-AuNCs, which results from the degradation of its structure due to the formation of Au2S by the reaction between Au and S2−. The proposed highly sensitive (the detection limit [LD] was 0.029μM) and selective sensor was applied to the detection of S2− in the presence of high concentrations of different anions in aqueous solution, and the results were in good agreement with those determined by electrochemical methods. The sensor is shown to be environmentally friendly, simple, responsive and practical. Meanwhile, the morphological changes of BSA-AuNCs and BSA-AuNCs-S2− were characterized by high-resolution transmission electron microscopy (HRTEM). Furthermore, the sensing mechanism for the detection of S2− is discussed.
Flavone modified-β-cyclodextrin as a highly selective and efficient fluorescent chemosensor for Cu2+ ions and l-histidine
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Ismail Abulkalam Azath , Kasi Pitchumani
7-Aminoflavone modified β-cyclodextrin with a hydrazinecarbothioamide linker is synthesised for the first time and characterised by NMR, ESI-MS and elemental analysis. NOESY as well as emission spectra indicate the inclusion of phenyl ring inside the cyclodextrin cavity. The hydrazinecarbothioamide linker acts as the metal binding unit. This flavone modified CD selectively binds with Cu(II) over other metal ions. Binding with Cu(II) makes the complex non-fluorescent. Addition of histidine, among other amino acids, results in regeneration of the fluorescence enhancement. This is due to the fact that l-histidine displaces Cu2+ from Flav-CD-Cu2+ complex to release the free flavone resulting in regeneration of its fluorescence. This turn-on sensor can be utilised effectively to sense both Cu(II) among various metal ions and l-histidine (as well as histamine) among various amino acids.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Ismail Abulkalam Azath , Kasi Pitchumani
7-Aminoflavone modified β-cyclodextrin with a hydrazinecarbothioamide linker is synthesised for the first time and characterised by NMR, ESI-MS and elemental analysis. NOESY as well as emission spectra indicate the inclusion of phenyl ring inside the cyclodextrin cavity. The hydrazinecarbothioamide linker acts as the metal binding unit. This flavone modified CD selectively binds with Cu(II) over other metal ions. Binding with Cu(II) makes the complex non-fluorescent. Addition of histidine, among other amino acids, results in regeneration of the fluorescence enhancement. This is due to the fact that l-histidine displaces Cu2+ from Flav-CD-Cu2+ complex to release the free flavone resulting in regeneration of its fluorescence. This turn-on sensor can be utilised effectively to sense both Cu(II) among various metal ions and l-histidine (as well as histamine) among various amino acids.
Sensitive and selective determination of uric acid in real samples by modified glassy carbon electrode with holmium fluoride nanoparticles/multi-walled carbon nanotube as a new biosensor
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): M. Noroozifar , M. Khorasani-Motlagh , F. Zareian Jahromi , S. Rostami
A novel modified glassy carbon electrode with holmium fluoride (HoF3) nanoparticles (HoFNPs)-multiwalled carbon nanotubes (MWCNTs) is fabricated and then successfully used for the sensitive and selective determination of uric acid (UA) in the presence of ascorbic acid (AA) and dopamine (DA). HoFNPs are successfully attached on the multi-walled carbon nanotubes (MWCNTs) via the intermediate of noncovalent hydrophobic interactions of the MWCNTs surface with sodium dodecyl sulfate (SDS). A detailed investigation by transmission electron microscopy (TEM) and electrochemistry is performed in order to elucidate the preparation process and properties of the nanocomposites. TEM image shows that the particle size of HoFNPs is about 56nm. Linear calibration plot is obtained over the range 2.0×10−7–5.0×10 −4 M (0.2–500.0μM) with a detection limit 1.6×10−7 M (0.16μM) for UA. The modified carbon electrode proves to have good sensitivity, stability and performance for determination UA in the presence of AA, DA in human blood serum and urine samples.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): M. Noroozifar , M. Khorasani-Motlagh , F. Zareian Jahromi , S. Rostami
A novel modified glassy carbon electrode with holmium fluoride (HoF3) nanoparticles (HoFNPs)-multiwalled carbon nanotubes (MWCNTs) is fabricated and then successfully used for the sensitive and selective determination of uric acid (UA) in the presence of ascorbic acid (AA) and dopamine (DA). HoFNPs are successfully attached on the multi-walled carbon nanotubes (MWCNTs) via the intermediate of noncovalent hydrophobic interactions of the MWCNTs surface with sodium dodecyl sulfate (SDS). A detailed investigation by transmission electron microscopy (TEM) and electrochemistry is performed in order to elucidate the preparation process and properties of the nanocomposites. TEM image shows that the particle size of HoFNPs is about 56nm. Linear calibration plot is obtained over the range 2.0×10−7–5.0×10 −4 M (0.2–500.0μM) with a detection limit 1.6×10−7 M (0.16μM) for UA. The modified carbon electrode proves to have good sensitivity, stability and performance for determination UA in the presence of AA, DA in human blood serum and urine samples.
A simple homemade light emitting diode based photometer for chromium speciation
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Mohammad-Hossein Sorouraddin , Masoud Saadati , Hasan Karimi baneshat
A simple spectrophotometric method utilizing a homemade light emitting diode (LED) based photometer is developed for chromium (VI) and total chromium determination in water samples. The photometer is composed of an LED (white color) as light source and a programmable light-to-frequency converter (three arrays of photodiodes each with a red, green or blue filter) as a detector. The chromium speciation is based on the complex formation reaction of Cr(VI) with 1,5-diphenylcarbazide. Considering the maximum absorption wavelength of the complex, the determination was performed using green filter detector. Prior to the total chromium determination, Cr(III) was oxidized to Cr(VI) with Ce(IV). Cr(III) concentration was calculated from the difference between total Cr and Cr(VI) concentrations. Under the optimum conditions, the calibration graph was linear in 10–200μgL−1 chromium concentration range. The relative standard deviation (n =5) and the limit of detection was calculated to be 2.45 and 2.99μgL−1 respectively. The proposed method was successfully applied to chromium speciation in spiked water samples.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Mohammad-Hossein Sorouraddin , Masoud Saadati , Hasan Karimi baneshat
A simple spectrophotometric method utilizing a homemade light emitting diode (LED) based photometer is developed for chromium (VI) and total chromium determination in water samples. The photometer is composed of an LED (white color) as light source and a programmable light-to-frequency converter (three arrays of photodiodes each with a red, green or blue filter) as a detector. The chromium speciation is based on the complex formation reaction of Cr(VI) with 1,5-diphenylcarbazide. Considering the maximum absorption wavelength of the complex, the determination was performed using green filter detector. Prior to the total chromium determination, Cr(III) was oxidized to Cr(VI) with Ce(IV). Cr(III) concentration was calculated from the difference between total Cr and Cr(VI) concentrations. Under the optimum conditions, the calibration graph was linear in 10–200μgL−1 chromium concentration range. The relative standard deviation (n =5) and the limit of detection was calculated to be 2.45 and 2.99μgL−1 respectively. The proposed method was successfully applied to chromium speciation in spiked water samples.
A novel impedimetric sensor based on molecularly imprinted polypyrrole modified pencil graphite electrode for trace level determination of chlorpyrifos
13 September 2013,
09:00:36
Publication date: November
2013
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Zihni Onur Uygun , Yusuf Dilgin
A chlorpyrifos (CPF) templated molecularly imprinted film was electrochemically synthesized on a pencil graphite electrode (PGE) by electropolymerization of pyrrole (Py) in the presence of CPF. The fabricated modified electrode was used as a novel impedimetric sensor for the determination of an important organophosphorus pesticide, CPF. The binding performance of CPF toward the polypyrrole (PPy) film was examined using electrochemical impedance spectroscopy (EIS). The surface morphology of the imprinted film was characterized by scanning electron microscopy (SEM). Results obtained from the impedance measurements show that imprinted PPy modified PGE offers a disposable, low cost, selective and sensitive electrochemical sensor for the determination of CPF. Under experimental conditions, the proposed impedimetric sensor has a linear response range from 20 to 300μgL−1 CPF with a detection limit of 4.5μgL−1 (based on 3sb). Furthermore, the fabricated sensor was successfully applied to determine CPF in CPF-added artificial samples.
Source:Sensors and Actuators B: Chemical, Volume 188
Author(s): Zihni Onur Uygun , Yusuf Dilgin
A chlorpyrifos (CPF) templated molecularly imprinted film was electrochemically synthesized on a pencil graphite electrode (PGE) by electropolymerization of pyrrole (Py) in the presence of CPF. The fabricated modified electrode was used as a novel impedimetric sensor for the determination of an important organophosphorus pesticide, CPF. The binding performance of CPF toward the polypyrrole (PPy) film was examined using electrochemical impedance spectroscopy (EIS). The surface morphology of the imprinted film was characterized by scanning electron microscopy (SEM). Results obtained from the impedance measurements show that imprinted PPy modified PGE offers a disposable, low cost, selective and sensitive electrochemical sensor for the determination of CPF. Under experimental conditions, the proposed impedimetric sensor has a linear response range from 20 to 300μgL−1 CPF with a detection limit of 4.5μgL−1 (based on 3sb). Furthermore, the fabricated sensor was successfully applied to determine CPF in CPF-added artificial samples.
No comments:
Post a Comment