| 1. |
- Amin, Sidra, et al.
(author)
-
A practical non-enzymatic urea sensor based on NiCo 2 O 4 nanoneedles
- 2019
-
In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:25, s. 14443-14451
-
Journal article (peer-reviewed)abstract
- We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo 2 O 4 ) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 μM) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo 2 O 4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo 2 O 4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo 2 O 4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co 3 O 4 . The GCE-modified electrode is highly sensitive towards urea, with a linear response (R 2 = 0.99) over the concentration range 0.01-5 mM and with a detection limit of 1.0 μM. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.
|
|
| 2. |
- Amin, Sidra, et al.
(author)
-
A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles
- 2019
-
In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:25, s. 14443-14451
-
Journal article (peer-reviewed)abstract
- We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 mu M) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R-2 = 0.99) over the concentration range 0.01-5 mM and with a detection limit of 1.0 mu M. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.
|
|
| 3. |
- Amin, Sidra, et al.
(author)
-
A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles
- 2019
-
In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:25, s. 14443-14451
-
Journal article (peer-reviewed)abstract
- We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 μM) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R2 = 0.99) over the concentration range 0.01–5 mM and with a detection limit of 1.0 μM. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.
|
|
| 4. |
- Andersson Ersman, Peter, et al.
(author)
-
Electrochromic Displays Screen Printed on Transparent Nanocellulose-Based Substrates
- 2023
-
In: Advanced Photonics Research. - : John Wiley & Sons, Ltd. - 2699-9293.
-
Journal article (peer-reviewed)abstract
- Manufacturing of electronic devices via printing techniques is often considered to be an environmentally friendly approach, partially due to the efficient utilization of materials. Traditionally, printed electronic components (e.g., sensors, transistors, and displays) are relying on flexible substrates based on plastic materials; this is especially true in electronic display applications where, most of the times, a transparent carrier is required in order to enable presentation of the display content. However, plastic-based substrates are often ruled out in end user scenarios striving toward sustainability. Paper substrates based on ordinary cellulose fibers can potentially replace plastic substrates, but the opaqueness limits the range of applications where they can be used. Herein, electrochromic displays that are manufactured, via screen printing, directly on state-of-the-art fully transparent substrates based on nanocellulose are presented. Several different nanocellulose-based substrates, based on either nanofibrillated or nanocrystalline cellulose, are manufactured and evaluated as substrates for the manufacturing of electrochromic displays, and the optical and electrical switching performances of the resulting display devices are reported and compared. The reported devices do not require the use of metals and/or transparent conductive oxides, thereby providing a sustainable all-printed electrochromic display technology.
|
|
| 5. |
- Arrigan, Damien, et al.
(author)
-
Selective voltammetric detection of dopamine in the presence ofascorbate
- 2004
-
In: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; :6, s. 732-733
-
Journal article (peer-reviewed)abstract
- The selective detection of dopamine in the presence of ascorbateis demonstrated based on the voltammetry of dopamine transferacross the interface between two immiscible electrolyte solutions(ITIES) facilitated by an organic-phase ionophore; ascorbatetransfer does not occur, leading to highly selectivedetection of dopamine in the presence of excess ascorbate.
|
|
| 6. |
|
|
| 7. |
- Azzouzi, Sawsen, et al.
(author)
-
An integrated dual functional recognition/amplification bio-label for the one-step impedimetric detection of Micro-RNA-21
- 2017
-
In: Biosensors & bioelectronics. - : ELSEVIER ADVANCED TECHNOLOGY. - 0956-5663 .- 1873-4235. ; 92, s. 154-161
-
Journal article (peer-reviewed)abstract
- Alteration in expression of miRNAs has been correlated with different cancer types, tumour stage and response to treatments. In this context, a structurally responsive oligonucleotide-based electrochemical impedimetric biosensor has been developed for the simple and sensitive detection of miRNA-21. A highly specific biotinylated DNA/LNA molecular beacon (MB) probe was conjugated with gold nanoparticles (AuNPs) to create an integrated, dual function bio-label (biotin-MB-AuNPs) for both biorecognition and signal generation. In the presence of target miRNA-21, hybridisation takes place resulting in the "activation" of the biotin-MB; this event makes the biotin group, which was previously "protected" by the steric hindrance of the MB stem-loop structure, accessible. The activated biotin-MB-AuNPs/miRNA complexes become available for capture, via supramolecular interaction, onto a nentravidin-modified electrode for electrochemical transduction. The binding event results in a decrease of the charge transfer resistance at the working electrode/electrolyte interface. The biosensor responded linearly in the range 1-1000 pM of miRNA-21, with a limit of detection of 0.3 pM, good reproducibility (Relative Standard deviation (RSD) =3.3%) and high selectivity over other miRNAs (i.e. miRNA221 and miRNA-205) sequences. Detection of miRNA-21 in spiked serum samples at clinically relevant levels (low pM range) was also demonstrated, thus illustrating the potential of the biosensor for point-of-care clinical applications. The proposed biosensor design, based on the combination of a neutravidin transducing surface and the dual-function biotin-MB-AuNPs bio-label, provides a simple and robust approach for detection of short-length nucleic acid targets, such as miRNAs.
|
|
| 8. |
- Bagheryan, Z., et al.
(author)
-
Diazonium-based impedimetric aptasensor for the rapid label-free detection of Salmonella typhimurium in food sample
- 2016
-
In: Biosensors & bioelectronics. - : Elsevier Ltd. - 0956-5663 .- 1873-4235. ; 80, s. 566-573
-
Journal article (peer-reviewed)abstract
- Fast and accurate detection of microorganisms is of key importance in clinical analysis and in food and water quality monitoring. Salmonella typhimurium is responsible for about a third of all cases of foodborne diseases and consequently, its fast detection is of great importance for ensuring the safety of foodstuffs.We report the development of a label-free impedimetric aptamer-based biosensor for S. typhimurium detection. The aptamer biosensor was fabricated by grafting a diazonium-supporting layer onto screen-printed carbon electrodes (SPEs), via electrochemical or chemical approaches, followed by chemical immobilisation of aminated-aptamer. FTIR-ATR, contact angle and electrochemical measurements were used to monitor the fabrication process. Results showed that electrochemical immobilisation of the diazonium-grafting layer allowed the formation of a denser aptamer layer, which resulted in higher sensitivity. The developed aptamer-biosensor responded linearly, on a logarithm scale, over the concentration range 1×101 to 1×108 CFU mL-1, with a limit of quantification (LOQ) of 1×101 CFU mL-1 and a limit of detection (LOD) of 6 CFU mL-1. Selectivity studies showed that the aptamer biosensor could discriminate S. typhimurium from 6 other model bacteria strains. Finally, recovery studies demonstrated its suitability for the detection of S. typhimurium in spiked (1×102, 1×104 and 1×106 CFU mL-1) apple juice samples.
|
|
| 9. |
|
|
| 10. |
- Beni, Valerio
(author)
-
Biosensors for Food and the Environment: Is it all in the DNA?
- 2013
-
Conference paper (other academic/artistic)abstract
- Biosensor technology not only holds great promise for the healthcare market but it is also expected to have significant impacts in other areas such as environmental and food analysis. Between the different biosensor formats nucleic acid-based biosensors are gaining increasingly importance allowing the specific identification of DNA/RNA fragments and, more recently, the detection of biological or chemical species. Direct identification of DNA/RNA fragments, via hybridisation assays (genosensors), has been shown to be a very powerful tool for the detection of pathogens in environment and food, in food contamination analysis and food allergens monitoring. Recently the discovery of aptamers, synthetic receptors based on short functional DNA/RNA chains, has opened new opportunities for oligonucleotide based biosensors and more specifically in the detection of biological and/or chemical species, such as proteins and pollutants. In this paper an overview of the most recent advances in the development and applications of nucleic acid-based biosensors for environmental and food safety/quality application will be presented with special emphasis on electrochemical and optical hybridisation genosensors and aptasensors.
|
|
| 11. |
- Beni, Valerio, et al.
(author)
-
Cyclic and pulse voltammetric study of dopamine at the interfacebetween two immiscible electrolyte solutions
- 2005
-
In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 20:10, s. 2097-2103
-
Journal article (peer-reviewed)abstract
- The detection of dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at the interface between twoimmiscible electrolyte solutions (ITIES) has been studied. Voltammetry at the liquid/liquid (water/1,2-dichloroethane) interface provides asimple method for overcoming the major problem associated with dopamine detection by voltammetry at solid electrodes: the co-existenceof ascorbate at higher concentrations. Selectivity for dopamine was achieved by the use of dibenzo-18-crown-6 as an ionophore for thefacilitated transfer voltammetry of protonated dopamine across the ITIES. Under these conditions, ascorbate is not transferred and hence doesnot interfere in the ion transfer current for dopamine. By use of DPV and SWV, the lowest concentration detectable can be lowered from ca.0.1mM (obtained with cyclic voltammetry) to 2 M. Evaluation of the effect of some other physiologically important species (acetylcholine,sodium, potassium and ammonium ions) on the dopamine transfer voltammetry has been studied, indicating the need for improved ionophoredesigns in order to achieve practically useful selectivity.
|
|
| 12. |
- Beni, Valerio, et al.
(author)
-
Development of a gold nano-particle-based fluorescent molecular beacon fordetection of cystic fibrosis associated mutation
- 2010
-
In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 26:2, s. 307-313
-
Journal article (peer-reviewed)abstract
- Cystic fibrosis is one of the most common genetically inherited diseases in Northern Europe, consistingof an inherited defect of chloride transport in the epithelium. Of the several mutations related to CF, theF508 mutation occurs in ca. 70% of the cases. In this work the use of a gold nano-particle supportedfluorescence molecular beacon was investigated as an optical sensing platform for the detection of theF508 cystic fibrosis associated mutation. Different parameters such as molecular beacon design, Aunano-particle size, molecular beacon–nano-particle conjugation protocol, molecular beacon loading aswell as experimental conditions were evaluated. A 31-base long molecular beacon, containing a 15-baserecognition sequence specific for the mutant target, was linked via a thiol modified poly thymine linker(10 bases long) to a 13 nm gold nano-particle and was exposed to mutant and wild type targets, and aclear differentiation was achieved at target concentrations as low as 1 nM.
|
|
| 13. |
- Beni, Valerio, et al.
(author)
-
Development of a portable electroanalytical system for the stripping voltammetry of metals : Determination of copper in acetic acid soil extracts
- 2005
-
In: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 552:1-2, s. 190-200
-
Journal article (peer-reviewed)abstract
- The development, characterisation and evaluation of a prototype portable electrochemical trace metal analyser are presented. The instrumentis a battery-powered microcontroller-based potentiostat, which implements anodic stripping voltammetry (ASV) at suitable sensor electrodes.It is capable of operating away from the laboratory, in the absence of an external power source and is usable by low-skilled personnel. Thedistinguishing feature of the instrument is its custom software, which enables sample pre-screening, data processing and sample dilution andstandard additions calculations to be carried out. The instrument has been evaluated by application of a methodology for the detection ofcopper in acetic acid soil extracts, both in the laboratory and in the field. Underpotential deposition staircase anodic stripping voltammetry(UPD-SCASV) of the copper at gold disk electrodes was used as a test method. There was good agreement between the instrument resultsand those from laboratory-based reference analytical methods for analyses carried out both in the laboratory and in the field.
|
|
| 14. |
- Beni, Valerio
(author)
-
Development of an electrochemical genosensors for celiac disease predisposition analysis
- 2013
-
In: "Biomimetic structures and DNA technology in biosensing". - 9788081470066 ; , s. 21-
-
Conference paper (other academic/artistic)abstract
- Low density DNA arrays are of growing interest in the field of fast clinical/environmental analysis; for example in clinical analysis these can find application in areas as early diagnosis of genetic diseases or as support in the diagnosis of genetically associated diseases. Coeliac disease, a small intestinal inflammation triggered by the intake of gluten, has been shown to affect only genetically predisposed individuals. Relation between Coeliac disease and two Human Leukocyte Antigens (HLA) genes, DQ2 and DQ8, has been reported, with almost 100% of the affected patients carrying at least one of them.In this seminar the development of a low density electrochemical genosensor array for medium resolution typing of Coeliac disease associated HLA genes, is presented. The proposed array was based on an enzymatic sandwich assay format performed at a photolitographically fabricated electrode array. The optimisation of different aspects as surface chemistry, assay conditions, probe's design and single stranded DNA generation, together with real sample analysis will be present.
|
|
| 15. |
- Beni, Valerio, et al.
(author)
-
Electrochemical properties of polymeric nanopatterned electrodes
- 2007
-
In: Electrochemistry communications. - : Elsevier. - 1388-2481 .- 1873-1902. ; 9:7, s. 1833-1839
-
Journal article (peer-reviewed)abstract
- An investigation of the electrochemical behaviour of gold electrodes coated with poly(ethylene glycol) (PEG), poly(acrylic acid)(PAA) and nanopatterned PAA/PEG layers is presented. Plasma-enhanced chemical vapour deposition and colloidal lithography wereused to produce nanodomes of PAA in a matrix of PEG. The electrochemical response at these nanostructured electrodes was studied asa function of the probe ion charge. Results show that the film structures allow the electrodes to retain their electrochemical activity whileminimising surface fouling and will thus be useful in the development of electrochemical nanobiosensors for various applications.
|
|
| 16. |
- Beni, Valerio, et al.
(author)
-
Gold nanoparticle fluorescent molecular beacon for low-resolution DQ2 gene HLA typing
- 2012
-
In: Analytical and Bioanalytical Chemistry. - : Springer Berlin/Heidelberg. - 1618-2642 .- 1618-2650. ; 402:3, s. 1001-1009
-
Journal article (peer-reviewed)abstract
- Coeliac disease is an inflammation of the small intestine triggered by gluten ingestion. We present a fluorescent genosensor, exploiting molecular-beacon-functionalized gold nanoparticles, for the identification of human leukocyte antigen (HLA) DQ2 gene, a key genetic factor in coeliac disease. Optimization of sensor performance was achieved by tuning the composition of the oligonucleotide monolayer immobilized on the gold nanoparticle and the molecular beacon design. Co-immobilization of the molecular beacon with a spacing oligonucleotide (thiolated ten-thymine oligonucleotide) in the presence of ten-adenine oligonucleotides resulted in a significant increase of the sensor response owing to improved spacing of the molecular beacons and extension of the distance from the nanoparticle surface, which renders them more available for recognition. Further increase in the response (approximately 40%) was shown to be achievable when the recognition sequence of the molecular beacon was incorporated in the stem. Improvement of the specificity of the molecular beacons was also achieved by the incorporation within their recognition sequence of a one-base mismatch. Finally, gold nanoparticles functionalized with two molecular beacons targeting the DQA1*05* and DQB1*02* alleles allowed the low-resolution typing of the DQ2 gene at the nanomolar level.
|
|
| 17. |
- Beni, Valerio, et al.
(author)
-
Investigation into the voltammetric behaviour and detection of selenium(IV) at metal electrodes in diverse electrolyte media
- 2011
-
In: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 699:2, s. 127-133
-
Journal article (peer-reviewed)abstract
- The voltammetric behaviour of selenium(IV) was studied at platinum and gold electrodes in sulphuricacid, perchloric acid and potassium chloride media as a basis for its voltammetric detection. The bestvoltammetric behaviour was recorded at gold electrodes with perchloric acid as the supporting electrolyte.The concomitant presence of metals, such as copper or lead, and of model biomolecules, suchas bovine serum albumin, in the solution resulted in a deterioration of the electrochemical response forselenium(IV). Quantitative detection of selenium(IV) by square wave anodic stripping voltammetry atboth a millimetre-sized gold disc electrode and a microband electrode array revealed linear responsesto selenium concentration in the ranges 5–15 M and 0.1–10 M, respectively, with 60 s preconcentration.The sensitivities were 6.4 A M−1 cm−2 and 100 A M−1 cm−2 at the disc and the microband array,respectively. The detection limit at the microband electrode array was 25 nM, illustrating the potentialityof such microelectrodes for the development of mercury-free analytical methods for the trace detectionof selenium(IV).
|
|
| 18. |
- Beni, Valerio, et al.
(author)
-
Microelectrode arrays and microfabricated devices in electrochemical stripping analysis
- 2008
-
In: Current Analytical Chemistry. - : Bentham Science Publishers. - 1573-4110 .- 1875-6727. ; 4:3, s. 229-241
-
Journal article (peer-reviewed)abstract
- In this article a comprehensive overview of the developments in the field of electrochemical stripping analysis with microelectrode arrays and microfabricated devices is presented. Due to the vastness of the topic, this mini-review deals only with the use of regular microelectrode arrays. After the description of the main fabrication methodologies employed, a large part of the review is dedicated to applications, categorised by the electrode material. Microelectrode arrays have found application in several areas of electroanalytical science including clinical and environmental analysis. They have been used for the detection of heavy metals in waters, soil extracts and blood, proving to be reliable analytical devices and bringing the advantages of low-cost, simplicity of use and easy adaptability to field measurement. In many applications, limits of detection are sub-parts per billion. Finally a short section of the review discusses miniaturised potentiostats.
|
|
| 19. |
- Beni, Valerio, 1972-, et al.
(author)
-
Printed electrochemical instruments for biosensors
- 2015
-
In: ECS Transactions. - : The Electrochemical Society. - 9781607685395 ; , s. 1-13
-
Conference paper (peer-reviewed)abstract
- Mobile diagnostics for healthcare, food safety and environmental monitoring, demand a new generation of inexpensive sensing systems suitable for production in high volume. Herein we report on the development of a new disposable electrochemical instrument exploiting the latest advances in printed electronics and printed biosensors. The current system is manufactured under ambient conditions with all interconnections printed; electrochemical measurements and data elaboration are realized by the integration onto the platform of two chips: a MICROCHIP-PIC24F16KA101 and a Texas Instrument's LMP91000. A PEDOT.PSS vertical electrochromic display (VECD) is also incorporated into the system to visualize the data. A printed Enfucell 3V manganese dioxide battery was used to deliver the required power. Finally, in order to demonstrate the utility of the system, screen-printed sensors for the detection of glucose were added and the performance of the overall system was evaluated.
|
|
| 20. |
- Beni, Valerio, et al.
(author)
-
Printed electrochemical instruments for biosensors
- 2015
-
In: ECS Journal of Solid State Science and Technology. - : Electrochemical Society Inc.. - 2162-8769 .- 2162-8777. ; 4:10, s. S3001-S3005
-
Journal article (peer-reviewed)abstract
- Mobile diagnostics for healthcare, food safety and environmental monitoring, demand a new generation of inexpensive sensing systems suitable for production in high volume. Herein we report on the development of a new disposable electrochemical instrument exploiting the latest advances in printed electronics and printed biosensors. The current system is manufactured under ambient conditions with all interconnections printed; electrochemical measurements and data elaboration are realized by the integration onto the platform of two chips: a MICROCHIP-PIC24F16KA101 and a Texas Instrument's LMP91000. A PEDOT.PSS vertical electrochromic display (VECD) is also incorporated into the system to visualize the data. A printed Enfucell 3V manganese dioxide battery was used to deliver the required power. Finally, in order to demonstrate the utility of the system, screen-printed sensors for the detection of glucose were added and the performance of the overall system was evaluated.
|
|
| 21. |
- Beni, Valerio, et al.
(author)
-
Study of the combination of the deposition/stripping of sacrificial metal nano-structures and alkanethiol as a route for genosensor surface preparation
- 2011
-
In: Electrochemistry communications. - : Elsevier. - 1388-2481 .- 1873-1902. ; 13:4, s. 325-327
-
Journal article (peer-reviewed)abstract
- In the reported work the combination of electrodeposition/stripping of copper sacrificial metallic nanostructuresand alkanethiol self-assembling was investigated for the preparation of a randomly nano-patternedorganised monolayer on a gold surface. Electrochemical characterisation of the process demonstrated thepotential of the proposed approach for the random nano-patterning of a chemisorbed monolayer onconductive surfaces with minimal impact on the bulk monolayer. Finally the obtained nano-structuredsurfaces were exploited as a platform for the fabrication of an amperometric genosensor for the detection ofthe DF508 Cystic Fibrosis associated mutation.
|
|
| 22. |
- Beni, Valerio, et al.
(author)
-
Voltammetric behaviour at gold electrodes immersed in the BCR sequential extraction scheme media : Application of underpotential deposition–stripping voltammetry to determination of copper in soil extracts
- 2004
-
In: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 502:2, s. 195-206
-
Journal article (peer-reviewed)abstract
- The development of mercury-free electroanalytical systems for in-field analysis of pollutants requires a foundation on the electrochemicalbehaviour of the chosen electrode material in the target sample matrices. In this work, the behaviour of gold working electrodes in the mediaemployed in the BCR sequential extraction protocol, for the fractionation of metals in solid environmental matrices, is reported. All three ofthe BCR sequential extraction media are redox active, on the basis of acidity and oxygen content as well as the inherent reducing or oxidisingnature of some of the reagents employed: 0.11M acetic acid, 0.1M hydroxylammonium chloride (adjusted to pH 2) and 1M ammoniumacetate (adjusted to pH 2) with added trace hydrogen peroxide. The available potential ranges together with the demonstrated detection oftarget metals in these media are presented. Stripping voltammetry of copper or lead in the BCR extract media solutions reveal a multi-peakbehaviour due to the stripping of both bulk metal and underpotential metal deposits. A procedure based on underpotential deposition–strippingvoltammetry (UPD-SV) was evaluated for application to determination of copper in 0.11M acetic acid soil extracts. A preliminary screeningstep in which different deposition times are applied to the sample enables a deposition time commensurate with UPD-SV to be selected sothat no bulk deposition or stripping occurs thus simplifying the shape and features of the resulting voltammograms. Choice of the suitabledeposition time is then followed by standards addition calibration. The method was validated by the analysis of a number of BCR 0.11Macetic acid soil extracts. Good agreement was obtained been the UPD-SV method and atomic spectroscopic results.
|
|
| 23. |
- Berduque, Alfonso, et al.
(author)
-
Voltammetric characterisation of silicon-based microelectrode arrays and their application to mercury-free stripping voltammetry of copper ions
- 2007
-
In: Talanta. - : Elsevier. - 0039-9140 .- 1873-3573. ; 71:3, s. 1022-1030
-
Journal article (peer-reviewed)abstract
- This paper describes the electrochemical characterisation of a range of gold and platinum microelectrode arrays (MEAs) fabricated by standardphotolithographic methods. The inter-electrode spacing, geometry, numbers and dimensions of the electrodes in the arrays were found to influencethe voltammetric behaviours obtained. Excellent correlation was found between experimental data and theoretical predictions employing publishedmodels of microelectrode behaviour. Gold MEAs were evaluated for their applicability to copper determination in a soil extract sample, whereagreement was found between the standard analytical method and a method based on underpotential deposition—anodic stripping voltammetry(UPD-ASV) at the MEAs, offering a mercury-free alternative for copper sensing.
|
|
| 24. |
- Berto, Marcello, et al.
(author)
-
Label free urea biosensor based on organic electrochemical transistors
- 2018
-
In: Flexible and Printed Electronics. - : IOP Publishing. - 2058-8585. ; 3:2
-
Journal article (peer-reviewed)abstract
- The quantification of urea is of the utmost importance not only in medical diagnosis, where it serves as a potential indicator of kidney and liver disfunction, but also in food safety and environmental control. Here, we describe a urea biosensor based on urease entrapped in a crosslinked gelatin hydrogel, deposited onto a fully printed PEDOT:PSS-based organic electrochemical transistor (OECT). The device response is based on the modulation of the channel conductivity by the ionic species produced upon urea hydrolysis catalyzed by the entrapped urease. The biosensor shows excellent reproducibility, a limit of detection as low as 1 μM and a response time of a few minutes. The fabrication of the OECTs by screen-printing on flexible substrates ensures a significant reduction in manufacturing time and costs. The low dimensionality and operational voltages (0.5 V or below) of these devices contribute to make these enzymatic OECT-based biosensors as appealing candidates for high-throughput monitoring of urea levels at the point-of-care or in the field.
|
|
| 25. |
- Boda, Ulrika, et al.
(author)
-
Fully Screen-Printed Stretchable Organic Electrochemical Transistors
- 2023
-
In: Advanced Materials Technologies. - : John Wiley and Sons Inc. - 2365-709X. ; :16
-
Journal article (peer-reviewed)abstract
- Stretchable organic electrochemical transistors (OECTs) are promising for wearable applications within biosensing, bio-signal recording, and addressing circuitry. Efficient large-scale fabrication of OECTs can be performed with printing methods but to date there are no reports on high-performance fully printed stretchable OECTs. Herein, this challenge is addressed by developing fully screen-printed stretchable OECTs based on an architecture that minimizes electrochemical side reactions and improves long-term stability. Fabrication of the OECTs is enabled by in-house development of three stretchable functional screen-printing inks and related printing processes. The stretchable OECTs show good characteristics in terms of transfer curves, output characteristics, and transient response up to 100% static strain and 500 strain cycles at 25% and 50% strain. The strain insensitivity of the OECTs can be further improved by strain conditioning, resulting in stable performance up to 50% strain. Finally, an electrochromic smart pixel is demonstrated by connecting a stretchable OECT to a stretchable electrochromic display. It is believed that the development of screen-printed stretchable electrochemical devices, and OECTs in particular, will pave the way for their use in wearable applications and commercial products. © 2023 The Authors.
|
|
