1
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Khuda N, Somasundaram S, Urgunde AB, Easley CJ. Ionic Strength and Hybridization Position near Gold Electrodes Can Significantly Improve Kinetics in DNA-Based Electrochemical Sensors. ACS Appl Mater Interfaces 2023; 15:5019-5027. [PMID: 36661270 PMCID: PMC10370289 DOI: 10.1021/acsami.2c22741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
A variety of electrochemical (EC) biosensors play critical roles in disease diagnostics. More recently, DNA-based EC sensors have been established as promising for detecting a wide range of analyte classes. Since most of these sensors rely on the high specificity of DNA hybridization for analyte binding or structural control, it is crucial to understand the kinetics of hybridization at the electrode surface. In this work, we have used methylene blue-labeled DNA strands to monitor the kinetics of DNA hybridization at the electrode surface with square-wave voltammetry. By varying the position of the double-stranded DNA segment relative to the electrode surface as well as the bulk solution's ionic strength (0.125-1.00 M), we observed significant interferences with DNA hybridization closer to the surface, with more substantial interference at lower ionic strength. As a demonstration of the effect, toehold-mediated strand displacement reactions were slowed and diminished close to the surface, while strategic placement of the DNA binding site improved reaction rates and yields. This work manifests that both the salt concentration and DNA hybridization site relative to the electrode are important factors to consider when designing DNA-based EC sensors that measure hybridization directly at the electrode surface.
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Affiliation(s)
- Niamat Khuda
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA
| | | | - Ajay B. Urgunde
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA
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2
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da Silva EP, Araujo MDS, Kunita MH, Matos R, Medeiros RA. Electrochemical Sensor Based on Multi-Walled Carbon Nanotubes and N-Doped TiO 2 Nanoparticles for Voltametric Simultaneous Determination of Benserazide and Levodopa. Molecules 2022; 27:molecules27238614. [PMID: 36500705 PMCID: PMC9739556 DOI: 10.3390/molecules27238614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/28/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022]
Abstract
An electrochemical sensor for simultaneous determination of Benserazide (BEZ) and levodopa (L-dopa) was successfully developed using a glassy carbon electrode (GCE) modified with multi-walled carbon nanotube and nitrogen-doped titanium dioxide nanoparticles (GCE/MWCNT/N-TiO2). Cyclic voltammetry and square wave voltammetry were employed to investigate the electrochemical behavior of different working electrodes and analytes. In comparison with unmodified GCE, the modified electrode exhibited better electrocatalytic activity towards BEZ and L-dopa and was efficient in providing a satisfactory separation for oxidation peaks, with a potential difference of 140 mV clearly allows the simultaneous determination of these compounds. Under the optimized conditions, linear ranges of 2.0-20.0 and 2.0-70.0 μmol L-1 were obtained for BEZ and L-dopa, respectively, with a limit of detection of 1.6 µmol L-1 for BEZ and 2.0 µmol L-1 for L-dopa. The method was applied in simultaneous determination of the analytes in pharmaceutical samples, and the accuracy was attested by comparison with HPLC-DAD as the reference method, with a relative error lower than 4.0%.
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Affiliation(s)
| | | | - Marcos H. Kunita
- Department of Chemistry, State University of Maringá, Maringá 87020-900, PR, Brazil
| | - Roberto Matos
- Department of Chemistry, State University of Londrina, Londrina 86057-970, PR, Brazil
| | - Roberta Antigo Medeiros
- Department of Chemistry, State University of Londrina, Londrina 86057-970, PR, Brazil
- Correspondence: ; Tel.: +55-43-33714811
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3
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Sen S, Roy A, Sanyal A, Devi PS. A nonenzymatic reduced graphene oxide-based nanosensor for parathion. Beilstein J Nanotechnol 2022; 13:730-744. [PMID: 35957670 PMCID: PMC9344548 DOI: 10.3762/bjnano.13.65] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/15/2022] [Indexed: 06/08/2023]
Abstract
Organophosphate-based pesticides (e.g., parathion (PT)) have toxic effects on human health through their residues. Therefore, cost-effective and rapid detection strategies need to be developed to ensure the consuming food is free of any organophosphate-residue. This work proposed the fabrication of a robust, nonenzymatic electrochemical-sensing electrode modified with electrochemically reduced graphene oxide (ERGO) to detect PT residues in environmental samples (e.g., soil, water) as well as in vegetables and cereals. The ERGO sensor shows a significantly affected electrocatalytic reduction peak at -0.58 V (vs Ag/AgCl) for rapid quantification of PT due to the amplified electroactive surface area of the modified electrode. At optimized experimental conditions, square-wave voltammetric analysis exhibits higher sensitivity (50.5 μA·μM-1·cm-2), excellent selectivity, excellent stability (≈180 days), good reproducibility, and repeatability for interference-free detection of PT residues in actual samples. This electrochemical nanosensor is suitable for point-of-care detection of PT in a wide dynamic range of 3 × 10-11-11 × 10-6 M with a lower detection limit of 10.9 pM. The performance of the nanosensor was validated by adding PT to natural samples and comparing the data via absorption spectroscopy. PT detection results encourage the design of easy-to-use nanosensor-based analytical tools for rapidly monitoring other environmental samples.
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Affiliation(s)
- Sarani Sen
- Functional Materials and Devices Division, CSIR-Central Glass & Ceramic Research Institute, 196 Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India
- National Institute of Technology Durgapur, Mahatma Gandhi Road, A-Zone, Durgapur, West Bengal 713209, India
| | - Anurag Roy
- Environment and Sustainability Institute, University of Exeter, Penryn Campus, Cornwall TR10 9FE, United Kingdom
| | - Ambarish Sanyal
- Functional Materials and Devices Division, CSIR-Central Glass & Ceramic Research Institute, 196 Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Parukuttyamma Sujatha Devi
- Chemical Sciences and Technology Division, CSIR-National Institute of Interdisciplinary Science and Technology, Thiruvananthapuram, Kerala 695019, India
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4
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Castagnola E, Robbins EM, Wu B, Pwint MY, Garg R, Cohen-Karni T, Cui XT. Flexible Glassy Carbon Multielectrode Array for In Vivo Multisite Detection of Tonic and Phasic Dopamine Concentrations. Biosensors (Basel) 2022; 12:540. [PMID: 35884343 PMCID: PMC9312827 DOI: 10.3390/bios12070540] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/13/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Dopamine (DA) plays a central role in the modulation of various physiological brain functions, including learning, motivation, reward, and movement control. The DA dynamic occurs over multiple timescales, including fast phasic release, as a result of neuronal firing and slow tonic release, which regulates the phasic firing. Real-time measurements of tonic and phasic DA concentrations in the living brain can shed light on the mechanism of DA dynamics underlying behavioral and psychiatric disorders and on the action of pharmacological treatments targeting DA. Current state-of-the-art in vivo DA detection technologies are limited in either spatial or temporal resolution, channel count, longitudinal stability, and ability to measure both phasic and tonic dynamics. We present here an implantable glassy carbon (GC) multielectrode array on a SU-8 flexible substrate for integrated multichannel phasic and tonic measurements of DA concentrations. The GC MEA demonstrated in vivo multichannel fast-scan cyclic voltammetry (FSCV) detection of electrically stimulated phasic DA release simultaneously at different locations of the mouse dorsal striatum. Tonic DA measurement was enabled by coating GC electrodes with poly(3,4-ethylenedioxythiophene)/carbon nanotube (PEDOT/CNT) and using optimized square-wave voltammetry (SWV). Implanted PEDOT/CNT-coated MEAs achieved stable detection of tonic DA concentrations for up to 3 weeks in the mouse dorsal striatum. This is the first demonstration of implantable flexible MEA capable of multisite electrochemical sensing of both tonic and phasic DA dynamics in vivo with chronic stability.
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Affiliation(s)
- Elisa Castagnola
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA; (E.C.); (E.M.R.); (B.W.); (M.Y.P.)
| | - Elaine M. Robbins
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA; (E.C.); (E.M.R.); (B.W.); (M.Y.P.)
| | - Bingchen Wu
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA; (E.C.); (E.M.R.); (B.W.); (M.Y.P.)
- Center for Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - May Yoon Pwint
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA; (E.C.); (E.M.R.); (B.W.); (M.Y.P.)
- Center for Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Raghav Garg
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (R.G.); (T.C.-K.)
| | - Tzahi Cohen-Karni
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (R.G.); (T.C.-K.)
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA; (E.C.); (E.M.R.); (B.W.); (M.Y.P.)
- Center for Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15261, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
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5
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Raj N, Crooks RM. Detection Efficiency of Ag Nanoparticle Labels for a Heart Failure Marker Using Linear and Square-Wave Anodic Stripping Voltammetry. Biosensors (Basel) 2022; 12:203. [PMID: 35448263 PMCID: PMC9029172 DOI: 10.3390/bios12040203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/23/2022] [Accepted: 03/26/2022] [Indexed: 12/11/2022]
Abstract
In this article, we compare linear sweep anodic stripping voltammetry (LASV) and square-wave anodic stripping voltammetry (SWASV) for detection of a nano metalloimmunoassay. Two separate immunoassays were examined: a model assay, based on interactions between antibodies, and a sandwich assay for the heart failure marker NT-proBNP. In both cases, one antibody is linked to a magnetic microbead, and one is linked to a spherical Ag nanoparticle label. Electrochemical detection is carried out on a paper device. The three analytical figures of merit studied were the precision of the measurements, the calibration sensitivity, and the limit of detection (LOD). For the NT-proBNP assay, the results show that after optimization of the pulse amplitude and frequency of the potential input for SWASV, the detection efficiency is substantially higher compared to LASV. Specifically, the calibration sensitivity increased by up to ~40 fold, the average coefficient of variation decreased by ~40%, and the (LOD) decreased to 300.0 pM. Finally, for a model immunoassay, a ~10-fold decrease in the LOD was observed for SWASV compared to LASV.
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Affiliation(s)
| | - Richard M. Crooks
- Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, TX 78712-1224, USA;
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6
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Khuda N, Somasundaram S, Easley CJ. Electrochemical Sensing of the Peptide Drug Exendin-4 Using a Versatile Nucleic Acid Nanostructure. ACS Sens 2022; 7:784-789. [PMID: 35180342 PMCID: PMC8985241 DOI: 10.1021/acssensors.1c02336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although endogenous peptides and peptide-based therapeutics are both highly relevant to human health, there are few approaches for sensitive biosensing of this class of molecules with minimized workflow. In this work, we have further expanded on the generalizability of our recently developed DNA nanostructure architecture by applying it to electrochemical (EC) peptide quantification. While DNA-small molecule conjugates were used in a prior work to make sensors for small molecule and protein analytes, here DNA-peptide conjugates were incorporated into the nanostructure at the electrode surfaces, and antibody displacement permitted rapid peptide sensing. Interestingly, multivalent DNA-peptide conjugates were found to be detrimental to the assay readout, yet these effects could be minimized by solution-phase bioconjugation. The final biosensor was validated for quantifying exendin-4 (4.2 kDa)─a human glucagon-like peptide-1 receptor agonist important in diabetes therapy─for the first time using EC methods with minimal workflow. The sensor was functional in 98% human serum, and the low nanomolar assay range lies between the injected dose concentration and the therapeutic range, boding well for future applications in therapeutic drug monitoring.
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7
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Yang Q, Nagar B, Alvarez-Diduk R, Balsells M, Farinelli A, Bloisi D, Proia L, Espinosa C, Ordeix M, Knutz T, De Vito-Francesco E, Allabashi R, Merkoçi A. Development of a Heavy Metal Sensing Boat for Automatic Analysis in Natural Waters Utilizing Anodic Stripping Voltammetry. ACS ES T Water 2021; 1:2470-2476. [PMID: 34918010 PMCID: PMC8669633 DOI: 10.1021/acsestwater.1c00192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 05/23/2023]
Abstract
Determination of the levels of heavy metal ions would support assessment of sources and pathways of water pollution. However, traditional spatial assessment by manual sampling and off-site detection in the laboratory is expensive and time-consuming and requires trained personnel. Aiming to fill the gap between on-site automatic approaches and laboratory techniques, we developed an autonomous sensing boat for on-site heavy metal detection using square-wave anodic stripping voltammetry. A fluidic sensing system was developed to integrate into the boat as the critical sensing component and could detect ≤1 μg/L Pb, ≤6 μg/L Cu, and ≤71 μg/L Cd simultaneously in the laboratory. Once its integration was completed, the autonomous sensing boat was tested in the field, demonstrating its ability to distinguish the highest concentration of Pb in an effluent of a galena-enriched mine compared to those at other sites in the stream (Osor Stream, Girona, Spain).
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Affiliation(s)
- Qiuyue Yang
- Nanobioelectronics
and Biosensors Group, Catalan Institute
of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona
Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Universitat
Autònoma de Barcelona, Department
of Material Science, Campus
de la UAB, Plaça Cívica, Bellaterra, 08193 Barcelona, Spain
| | - Bhawna Nagar
- Nanobioelectronics
and Biosensors Group, Catalan Institute
of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona
Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- École
Polytechnique Fédérale de Lausanne (EPFL) Valais Wallis,
Laboratory of Physical and Analytical Electrochemistry, Rue de l’Industrie 17, 1950 Sion, Switzerland
| | - Ruslán Alvarez-Diduk
- Nanobioelectronics
and Biosensors Group, Catalan Institute
of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona
Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Marc Balsells
- Nanobioelectronics
and Biosensors Group, Catalan Institute
of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona
Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Alessandro Farinelli
- University
of Verona, Department of Computer
Science, Ca Vignal 2,
Strada le Grazie 15, 37134 Verona, Italy
| | - Domenico Bloisi
- University
of Verona, Department of Computer
Science, Ca Vignal 2,
Strada le Grazie 15, 37134 Verona, Italy
- Department
of Mathematics, Computer Science, and Economics, University of Basilicata, 85100 Potenza, Italy
| | - Lorenzo Proia
- BETA Technological
Center, University of Vic-Central University
of Catalonia (UVic-UCC), 08500 Vic, Spain
| | - Carmen Espinosa
- BETA Technological
Center, University of Vic-Central University
of Catalonia (UVic-UCC), 08500 Vic, Spain
- CERM, Center
for the Study of Mediterranean Rivers, University of Vic-Central University
of Catalonia (UVic-UCC), 08560 Manlleu, Spain
| | - Marc Ordeix
- BETA Technological
Center, University of Vic-Central University
of Catalonia (UVic-UCC), 08500 Vic, Spain
- CERM, Center
for the Study of Mediterranean Rivers, University of Vic-Central University
of Catalonia (UVic-UCC), 08560 Manlleu, Spain
| | - Thorsten Knutz
- Go
Systemelektronik GmbH, Falunerweg 1, D-24109 Kiel, Germany
| | - Elisabetta De Vito-Francesco
- University
of Natural Resources and Life Sciences, Institute for Sanitary Engineering
and Water Pollution Control, Muthgasse 18, 1190 Vienna, Austria
| | - Roza Allabashi
- University
of Natural Resources and Life Sciences, Institute for Sanitary Engineering
and Water Pollution Control, Muthgasse 18, 1190 Vienna, Austria
| | - Arben Merkoçi
- Nanobioelectronics
and Biosensors Group, Catalan Institute
of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona
Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- ICREA, Pg. Lluís
Companys, 23, Barcelona 08010, Spain
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8
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Čižmek L, Bavcon Kralj M, Čož-Rakovac R, Mazur D, Ul’yanovskii N, Likon M, Trebše P. Supercritical Carbon Dioxide Extraction of Four Medicinal Mediterranean Plants: Investigation of Chemical Composition and Antioxidant Activity. Molecules 2021; 26:5697. [PMID: 34577168 PMCID: PMC8468049 DOI: 10.3390/molecules26185697] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 11/17/2022] Open
Abstract
With everyday advances in the field of pharmaceuticals, medicinal plants have high priority regarding the introduction of novel synthetic compounds by the usage of environmentally friendly extraction technologies. Herein, a supercritical CO2 extraction method was implemented in the analysis of four plants (chamomile, St. John's wort, yarrow, and curry plant) after which the non-targeted analysis of the chemical composition, phenolic content, and antioxidant activity was evaluated. The extraction yield was the highest for the chamomile (5%), while moderate yields were obtained for the other three plants. The chemical composition analyzed by gas chromatography-high-resolution mass spectrometry (GC-HRMS) and liquid chromatography-high-resolution mass spectrometry (LC-HRMS) demonstrated extraction of diverse compounds including terpenes and terpenoids, fatty acids, flavonoids and coumarins, functionalized phytosterols, and polyphenols. Voltammetry of microfilm immobilized on a glassy carbon electrode using square-wave voltammetry (SWV) was applied in the analysis of extracts. It was found that antioxidant activity obtained by SWV correlates well to 1,1-diphenyl-2-picrylhidrazine (DPPH) radical assay (R2 = 0.818) and ferric reducing antioxidant power (FRAP) assay (R2 = 0.640), but not to the total phenolic content (R2 = 0.092). Effective results were obtained in terms of activity showing the potential usage of supercritical CO2 extraction to acquire bioactive compounds of interest.
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Affiliation(s)
- Lara Čižmek
- Laboratory for Aquaculture Biotechnology, Division of Materials Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia; (L.Č.); (R.Č.-R.)
- Center of Excellence for Marine Bioprospecting (BioProCro), Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Mojca Bavcon Kralj
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia;
| | - Rozelindra Čož-Rakovac
- Laboratory for Aquaculture Biotechnology, Division of Materials Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia; (L.Č.); (R.Č.-R.)
- Center of Excellence for Marine Bioprospecting (BioProCro), Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Dmitrii Mazur
- Chemistry Department, Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia;
- Core Facility Center “Arktika”, Lomonosov Northern (Arctic) Federal University, nab. Severnoy Dviny 17, 163002 Arkhangelsk, Russia;
| | - Nikolay Ul’yanovskii
- Core Facility Center “Arktika”, Lomonosov Northern (Arctic) Federal University, nab. Severnoy Dviny 17, 163002 Arkhangelsk, Russia;
| | - Marko Likon
- Škrlj, d.o.o., Batuje 90, 5262 Črniče, Slovenia;
| | - Polonca Trebše
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, 1000 Ljubljana, Slovenia;
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9
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Johnson ZT, Williams K, Chen B, Sheets R, Jared N, Li J, Smith EA, Claussen JC. Electrochemical Sensing of Neonicotinoids Using Laser-Induced Graphene. ACS Sens 2021; 6:3063-3071. [PMID: 34370948 DOI: 10.1021/acssensors.1c01082] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neonicotinoids are the fastest-growing insecticide accounting for over 25% of the global pesticide market and are capable of controlling a range of pests that damage croplands, home yards/gardens, and golf course greens. However, widespread use has led to nontarget organism decline in pollinators, insects, and birds, while chronic, sublethal effects on humans are still largely unknown. Therefore, there is a need to understand how prevalent neonicotinoids are in the environment as there are currently no commercially available field-deployable sensors capable of measuring neonicotinoid concentrations in surface waters. Herein, we report the first example of a laser-induced graphene (LIG) platform that utilizes electrochemical sensing for neonicotinoid detection. These graphene-based sensors are created through a scalable direct-write laser fabrication process that converts polyimide into LIG, which eliminates the need for chemical synthesis of graphene, ink formulation, masks, stencils, pattern rolls, and postprint annealing commonly associated with other printed graphene sensors. The LIG electrodes were capable of monitoring four major neonicotinoids (CLO, IMD, TMX, and DNT) with low detection limits (CLO, 823 nM; IMD, 384 nM; TMX, 338 nM; and DNT, 682 nM) and a rapid response time (∼10 s) using square-wave voltammetry without chemical/biological functionalization. Interference testing exhibited negligible responses from widely used pesticides including the broad-leaf insecticides parathion, paraoxon, and fipronil, as well as systemic herbicides glyphosate (roundup), atrazine, dicamba, and 2,4-dichlorophenoxyacetic acid. These scalable, graphene-based sensors have the potential for wide-scale mapping of neonicotinoids in watersheds and potential use in numerous electrochemical sensor devices.
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Affiliation(s)
- Zachary T. Johnson
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 528 Bissell Road, Ames, Iowa 50010, United States
| | - Kelli Williams
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 528 Bissell Road, Ames, Iowa 50010, United States
| | - Bolin Chen
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 528 Bissell Road, Ames, Iowa 50010, United States
| | - Robert Sheets
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 528 Bissell Road, Ames, Iowa 50010, United States
| | - Nathan Jared
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 528 Bissell Road, Ames, Iowa 50010, United States
| | - Jingzhe Li
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- The Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Emily A. Smith
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- The Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Jonathan C. Claussen
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 528 Bissell Road, Ames, Iowa 50010, United States
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10
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Karastogianni S, Diamantidou D, Girousi S. Selective Voltammetric Detection of Ascorbic Acid from Rosa Canina on a Modified Graphene Oxide Paste Electrode by a Manganese(II) Complex. Biosensors (Basel) 2021; 11:294. [PMID: 34562884 PMCID: PMC8465974 DOI: 10.3390/bios11090294] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/15/2021] [Accepted: 08/24/2021] [Indexed: 05/27/2023]
Abstract
Voltammetric techniques have been considered as an important analytical tool applied to the determination of trace concentrations of many biological molecules including ascorbic acid. In this paper, ascorbic acid was detected by square wave voltammetry, using graphene oxide paste as a working electrode, modified by a film of a manganese(II) complex compound. Various factors, such as the effect of pH, affecting the response characteristics of the modified electrode were investigated. The relationship between the peak height and ascorbic acid concentration within the modified working electrode was investigated, using the calibration graph. The equation of the calibration graph was found to be: I = 0.0550γac + 0.155 with R2 = 0.9998, where I is the SWV current and γac is the mass concentration of ascorbic acid. The LOD and LOQ of the proposed method were determined to be 1.288 μg/L and 3.903 μg/L, respectively. Several compounds, such as riboflavin, biotin, and ions, such as Fe and Cu, were tested and it seemed that they did not interfere with the analytic signal. The proposed procedure was successfully applied in the determination of ascorbic acid in Rosa canina hips.
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Affiliation(s)
| | | | - Stella Girousi
- Analytical Chemistry Laboratory, Chemistry Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (S.K.); (D.D.)
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11
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Wettasinghe AP, Singh N, Starcher CL, DiTusa CC, Ishak-Boushaki Z, Kahanda D, McMullen R, Motea EA, Slinker JD. Detecting Attomolar DNA-Damaging Anticancer Drug Activity in Cell Lysates with Electrochemical DNA Devices. ACS Sens 2021; 6:2622-2629. [PMID: 34156840 DOI: 10.1021/acssensors.1c00365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Here, we utilize electrochemical DNA devices to quantify and understand the cancer-specific DNA-damaging activity of an emerging drug in cellular lysates at femtomolar and attomolar concentrations. Isobutyl-deoxynyboquinone (IB-DNQ), a potent and tumor-selective NAD(P)H quinone oxidoreductase 1 (NQO1) bioactivatable drug, was prepared and biochemically verified in cancer cells highly expressing NQO1 (NQO1+) and knockdowns with low NQO1 expression (NQO1-) by Western blot, NQO1 activity analysis, survival assays, oxygen consumption rate, extracellular acidification rate, and peroxide production. Lysates from these cells and the IB-DNQ drug were then introduced to a chip system bearing an array of DNA-modified electrodes, and their DNA-damaging activity was quantified by changes in DNA-mediated electrochemistry arising from base-excision repair. Device-level controls of NQO1 activity and kinetic analysis were used to verify and further understand the IB-DNQ activity. A 380 aM IB-DNQ limit of detection and a 1.3 fM midpoint of damage were observed in NQO1+ lysates, both metrics 2 orders of magnitude lower than NQO1- lysates, indicating the high IB-DNQ potency and selectivity for NQO1+ cancers. The device-level damage midpoint concentration in NQO1+ lysates was over 8 orders of magnitude lower than cell survival benchmarks, likely due to poor IB-DNQ cellular uptake, demonstrating that these devices can identify promising drugs requiring improved cell permeability. Ultimately, these results indicate the noteworthy potency and selectivity of IB-DNQ and the high sensitivity and precision of electrochemical DNA devices to analyze agents/drugs involved in DNA-damaging chemotherapies.
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Affiliation(s)
- Ashan P. Wettasinghe
- Department of Physics, The University of Texas at Dallas, 800 W. Campbell Road, SCI 10, Richardson, Texas 75080, United States
| | - Naveen Singh
- Department of Biochemistry and Molecular Biology, Simon Comprehensive Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, Walther Hall R3 C551, Indianapolis, Indiana 46202, United States
| | - Colton L. Starcher
- Department of Biochemistry and Molecular Biology, Simon Comprehensive Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, Walther Hall R3 C551, Indianapolis, Indiana 46202, United States
| | - Chloe C. DiTusa
- Department of Physics, The University of Texas at Dallas, 800 W. Campbell Road, SCI 10, Richardson, Texas 75080, United States
| | - Zakari Ishak-Boushaki
- Department of Physics, The University of Texas at Dallas, 800 W. Campbell Road, SCI 10, Richardson, Texas 75080, United States
| | - Dimithree Kahanda
- Department of Physics, The University of Texas at Dallas, 800 W. Campbell Road, SCI 10, Richardson, Texas 75080, United States
- Department of Physics, University of Peradeniya, Peradeniya 20400, Sri Lanka
| | - Reema McMullen
- Department of Physics, The University of Texas at Dallas, 800 W. Campbell Road, SCI 10, Richardson, Texas 75080, United States
| | - Edward A. Motea
- Department of Biochemistry and Molecular Biology, Simon Comprehensive Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, Walther Hall R3 C551, Indianapolis, Indiana 46202, United States
| | - Jason D. Slinker
- Department of Physics, The University of Texas at Dallas, 800 W. Campbell Road, SCI 10, Richardson, Texas 75080, United States
- Department of Materials Science and Engineering, The University of Texas at Dallas, 800 W. Campbell Road, SCI 10, Richardson, Texas 75080, United States
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12
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Abstract
An electrochemical sensor based on a conformation-changing aptamer is reported to detect soluble KIT, a cancer biomarker, in human serum. The sensor was fabricated with a ferrocene-labeled aptamer (Kd < 5 nM) conjugated to a gold electrode. Quantitative KIT detection was achieved using electrochemical impedance spectroscopy (EIS) and square-wave voltammetry (SWV). EIS was used to optimize experimental parameters such as the aptamer-to-spacer ratio, aptamer immobilization time, pH, and KIT incubation time, and the sensor surface was characterized using voltammetry. The assay specificity was demonstrated using interfering species and exhibited high specificity toward the target protein. The aptasensor showed a wide dynamic range, 10 pg/mL-100 ng/mL in buffer, with a 1.15 pg/mL limit of detection. The sensor also has a linear response to KIT spiked in human serum and successfully detected KIT in cancer-cell-conditioned media. The proposed aptasensor has applications as a continuous or intermittent approach for cancer therapy monitoring and diagnostics (theranostics).
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Affiliation(s)
- Saeromi Chung
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, United States
| | - Jason K Sicklick
- Department of Surgery, Division of Surgical Oncology, Moores Cancer Center, University of California San Diego Health, San Diego, California 92093, United States
| | - Partha Ray
- Department of Surgery, Division of Surgical Oncology, Moores Cancer Center, University of California San Diego Health, San Diego, California 92093, United States
| | - Drew A Hall
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, United States
- Department of Bioengineering, University of California San Diego, La Jolla, California 92093, United States
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13
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Chen LD, Wang WJ, Wang GJ. Electrochemical Detection of Electrolytes Using a Solid-State Ion-Selective Electrode of Single-Piece Type Membrane. Biosensors (Basel) 2021; 11:109. [PMID: 33917075 PMCID: PMC8067767 DOI: 10.3390/bios11040109] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 04/04/2021] [Indexed: 12/20/2022]
Abstract
This study aimed to develop simple electrochemical electrodes for the fast detection of chloride, sodium and potassium ions in human serum. A flat thin-film gold electrode was used as the detection electrode for chloride ions; a single-piece type membrane based solid-state ion-selective electrode (ISE), which was formed by covering a flat thin-film gold electrode with a mixture of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and ion-selective membrane (ISM), was developed for sodium and potassium ions detection. Through cyclic voltammetry (CV) and square-wave voltammetry (SWV), the detection data can be obtained within two minutes. The linear detection ranges in the standard samples of chloride, sodium, and potassium ions were 25-200 mM, 50-200 mM, and 2-10 mM, with the average relative standard deviation (RSD) of 0.79%, 1.65%, and 0.47% and the average recovery rates of 101%, 100% and 96%, respectively. Interference experiments with Na+, K+, Cl-, Ca2+, and Mg2+ ions demonstrated that the proposed detection electrodes have good selectivity. Moreover, the proposed detection electrodes have characteristics such as the ability to be prepared under relatively simple process conditions, excellent detection sensitivity, and low RSD, and the detection linear range is suitable for the Cl-, Na+ and K+ concentrations in human serum.
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Affiliation(s)
- Li-Da Chen
- Department of Mechanical Engineering, National Chung-Hsing University, Taichung 40227, Taiwan; (L.-D.C.); (W.-J.W.)
| | - Wei-Jhen Wang
- Department of Mechanical Engineering, National Chung-Hsing University, Taichung 40227, Taiwan; (L.-D.C.); (W.-J.W.)
| | - Gou-Jen Wang
- Department of Mechanical Engineering, National Chung-Hsing University, Taichung 40227, Taiwan; (L.-D.C.); (W.-J.W.)
- Graduate Institute of Biomedical Engineering, National Chung-Hsing University, Taichung 40227, Taiwan
- Regenerative Medicine and Cell Therapy Research Center, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
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14
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Majer D, Mastnak T, Finšgar M. An Advanced Statistical Approach Using Weighted Linear Regression in Electroanalytical Method Development for Epinephrine, Uric Acid and Ascorbic Acid Determination. Sensors (Basel) 2020; 20:s20247056. [PMID: 33317157 PMCID: PMC7763546 DOI: 10.3390/s20247056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 05/22/2023]
Abstract
In this study, the use of weighted linear regression in the development of electrochemical methods for the determination of epinephrine (EP), ascorbic acid (AA), and uric acid (UA) is presented. The measurements were performed using a glassy carbon electrode and square-wave voltammetry (SWV). All electroanalytical methods were validated by determination of the limit of detection, limit of quantification, linear concentration range, accuracy, and precision. The normal distribution of all data sets was checked using the quantile-quantile plot and Kolmogorov-Smirnov statistical tests. The heteroscedasticity of the data was tested using Hartley's test, Bartlett's test, Cochran's C test, and the analysis of residuals. The heteroscedastic behavior was observed with all analytes, justifying the use of weighted linear regression. Six different weighting factors were tested, and the best weighted model was determined using relative percentage error. Such statistical approach improved the regression models by giving greater weight on the values with the smallest error and vice versa. Consequently, accuracy of the analytical results (especially in the lower concentration range) was improved. All methods were successfully used for the determination of these analytes in real samples: EP in an epinephrine auto-injector, AA in a dietary supplement, and UA in human urine. The accuracy and precision of real sample analysis using best weighted model gave satisfactory results with recoveries between 95.21-113.23% and relative standard deviations between 0.85-7.98%. The SWV measurement takes about 40 s, which makes the presented methods for the determination of EP, AA, and UA a promising alternative to chromatographic techniques in terms of speed, analysis, and equipment costs, as the analysis is performed without organic solvents.
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15
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Chien JC, Baker SW, Soh HT, Arbabian A. Design and Analysis of a Sample-and-Hold CMOS Electrochemical Sensor for Aptamer-based Therapeutic Drug Monitoring. IEEE J Solid-State Circuits 2020; 55:2914-2929. [PMID: 33343021 PMCID: PMC7742970 DOI: 10.1109/jssc.2020.3020789] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In this paper, we present the design and the analysis of an electrochemical circuit for measuring the concentrations of therapeutic drugs using structure-switching aptamers. Aptamers are single-stranded nucleic acids, whose sequence is selected to exhibit high affinity and specificity toward a molecular target, and change its conformation upon binding. This property, when coupled with a redox reporter and electrochemical detection, enables reagent-free biosensing with a sub-minute temporal resolution for in vivo therapeutic drug monitoring. Specifically, we design a chronoamperometry-based electrochemical circuit that measures the direct changes in the electron transfer (ET) kinetics of a methylene blue reporter conjugated at the distal-end of the aptamer. To overcome the high-frequency noise amplification issue when interfacing with a large-size (> 0.25 mm2) implantable electrode, we present a sample-and-hold (S/H) circuit technique in which the desired electrode potentials are held onto noiseless capacitors during the recording of the redox currents. This allows disconnecting the feedback amplifiers to avoid its noise injection while reducing the total power consumption. A prototype circuit implemented in 65-nm CMOS demonstrates a cell-capacitance-insensitive input-referred noise (IRN) current of 15.2 pArms at a 2.5-kHz filtering bandwidth. We tested our system in human whole blood samples and measured the changes in the ET kinetics from the redox-labeled aptamers at different kanamycin concentrations. By employing principal component analysis (PCA) to compensate for the sampling errors, we report a molecular noise floor (at SNR = 1) of 3.1 µM with sub 1-sec acquisition time at 0.22-mW power consumption.
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Affiliation(s)
- Jun-Chau Chien
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Sam W Baker
- Department of Comparative Medicine, Stanford University, Stanford, CA 94305 USA
| | - H Tom Soh
- Department of Radiology and the Department of Electrical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Amin Arbabian
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305 USA
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16
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Szczepaniak O, Ligaj M, Kobus-Cisowska J, Tichoniuk M, Dziedziński M, Przeor M, Szulc P. The Genoprotective Role of Naringin. Biomolecules 2020; 10:biom10050700. [PMID: 32365989 PMCID: PMC7277402 DOI: 10.3390/biom10050700] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 12/14/2022] Open
Abstract
Since ancient times, fruits and edible plants have played a special role in the human diet for enhancing health and maintaining youthfulness. The aim of our work was to determine the interactions between naringin, a natural ingredient of grapefruits, and DNA using an electrochemical biosensor. Electrochemical methods allow analyzing the damages occurring in the structure of nucleic acids and their interactions with xenobiotics. Our study showed that the changes in the location of electrochemical signals and their intensity resulted from the structural alterations in DNA. The signal of adenine was affected at lower concentrations of naringin, but the signal of guanine was unaffected in the same condition. The dynamics of changes occurring in the peak height and surface of adenine related to naringin concentration was also significantly lower. The complete binding of all adenine bases present in the tested double-stranded DNA solution was observed at naringin concentrations ranging from 8.5 to 10.0 µM. At larger concentrations, this active compound exerted an oxidizing effect on DNA. However, the critical concentrations of naringin were found to be more than twice as high as the dose absorbable in an average human (4 µM). The results of our work might be helpful in the construction of electrochemical sensors for testing the content of polyphenols and would allow determining their genoprotective functionality.
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Affiliation(s)
- Oskar Szczepaniak
- Department of Gastronomy Sciences and Functional Foods, Poznań University of Life Sciences, 60-637 Poznań, Poland; (J.K.-C.); (M.D.); (M.P.)
- Correspondence: ; Tel.: +48-61-848-6330
| | - Marta Ligaj
- Department of Industrial Products Quality and Packaging Development, Poznań University of Economics and Business, 61-875 Poznań, Poland; (M.L.); (M.T.)
| | - Joanna Kobus-Cisowska
- Department of Gastronomy Sciences and Functional Foods, Poznań University of Life Sciences, 60-637 Poznań, Poland; (J.K.-C.); (M.D.); (M.P.)
| | - Mariusz Tichoniuk
- Department of Industrial Products Quality and Packaging Development, Poznań University of Economics and Business, 61-875 Poznań, Poland; (M.L.); (M.T.)
| | - Marcin Dziedziński
- Department of Gastronomy Sciences and Functional Foods, Poznań University of Life Sciences, 60-637 Poznań, Poland; (J.K.-C.); (M.D.); (M.P.)
| | - Monika Przeor
- Department of Gastronomy Sciences and Functional Foods, Poznań University of Life Sciences, 60-637 Poznań, Poland; (J.K.-C.); (M.D.); (M.P.)
| | - Piotr Szulc
- Department of Agronomy, Poznań University of Life Sciences, 60-637 Poznań, Poland;
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17
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Ruff A, Jaikaew W, Khunkaewla P, Schuhmann W, Schulte A. Drug Release from Polymer Thin Films and Gel Pellets: Insights from Programmed Microplate Electroanalysis. Chempluschem 2020; 85:627-633. [PMID: 32237228 DOI: 10.1002/cplu.202000129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/14/2020] [Indexed: 01/09/2023]
Abstract
Robotic electroanalysis in 24-well microplates was used to determine Paracetamol (PCT) release from thin films of chitosan and two pH-sensitive synthetic polymers as well as blends of the polymers with each other and with agarose. Square-wave voltammograms were recorded automatically in a potential window of 0.35 V-0.85 V vs. Ag/AgCl/0.1 M KCl and their evaluation revealed time-dependent PCT release into acidic and basic media. Comparison of the release profiles showed that pure chitosan layers released PCT quickly in a single-phase process while liberation from synthetic polymer thin films was slower with a sigmoidal shape at pH 1.2 and pH 8.0 with a maximum release of PCT after approximately 150 and 140 min, respectively. The release profile from thicker agarose films was between those of the thin films. Agarose blended with chitosan or synthetic polymers formed films with biphasic release behavior. Chitosan linearized the initial section of the release profile in chitosan/polymer blends. The automated procedure for release testing offers the advantage of low-cost, labor-effective and error-free data acquisition. The procedure has been validated as a useful microplate assay option for release profile testing.
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Affiliation(s)
- Adrian Ruff
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Wajee Jaikaew
- School of Chemistry, Biochemistry - Electrochemistry Research Unit Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - Panida Khunkaewla
- School of Chemistry, Biochemistry - Electrochemistry Research Unit Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - Wolfgang Schuhmann
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Albert Schulte
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Rayong, 21210, Thailand
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18
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Dauphin-Ducharme P, Yang K, Arroyo-Currás N, Ploense KL, Zhang Y, Gerson J, Kurnik M, Kippin TE, Stojanovic MN, Plaxco KW. Electrochemical Aptamer-Based Sensors for Improved Therapeutic Drug Monitoring and High-Precision, Feedback-Controlled Drug Delivery. ACS Sens 2019; 4:2832-2837. [PMID: 31556293 PMCID: PMC6886665 DOI: 10.1021/acssensors.9b01616] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The electrochemical aptamer-based (E-AB) sensing platform appears to be a convenient (rapid, single-step, and calibration-free) and modular approach to measure concentrations of specific molecules (irrespective of their chemical reactivity) directly in blood and even in situ in the living body. Given these attributes, the platform may thus provide significant opportunities to render therapeutic drug monitoring (the clinical practice in which dosing is adjusted in response to plasma drug measurements) as frequent and convenient as the measurement of blood sugar has become for diabetics. The ability to measure arbitrary molecules in the body in real time could even enable closed-loop feedback control over plasma drug levels in a manner analogous to the recently commercialized controlled blood sugar systems. As initial exploration of this, we describe here the selection of an aptamer against vancomycin, a narrow therapeutic window antibiotic for which therapeutic monitoring is a critical part of the standard of care, and its adaptation into an electrochemical aptamer-based (E-AB) sensor. Using this sensor, we then demonstrate: (i) rapid (seconds) and convenient (single-step and calibration-free) measurement of plasma vancomycin in finger-prick-scale samples of whole blood, (ii) high-precision measurement of subject-specific vancomycin pharmacokinetics (in a rat animal model), and (iii) high-precision, closed-loop feedback control over plasma levels of the drug (in a rat animal model). The ability to not only track (with continuous-glucose-monitor-like measurement frequency and convenience) but also actively control plasma drug levels provides an unprecedented route toward improving therapeutic drug monitoring and, more generally, the personalized, high-precision delivery of pharmacological interventions.
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Affiliation(s)
- Philippe Dauphin-Ducharme
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Kyungae Yang
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, New York 10032, United States
| | - Netzahualcóyotl Arroyo-Currás
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | - Kyle L. Ploense
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Yameng Zhang
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, New York 10032, United States
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Martin Kurnik
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Tod E. Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Milan N. Stojanovic
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, New York 10032, United States
- Department of Biomedical Engineering and Systems Biology, Columbia University, New York, New York 10032, United States
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
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19
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Zainul R, Abd Azis N, Md Isa I, Hashim N, Ahmad MS, Saidin MI, Mukdasai S. Zinc/Aluminium⁻Quinclorac Layered Nanocomposite Modified Multi-Walled Carbon Nanotube Paste Electrode for Electrochemical Determination of Bisphenol A. Sensors (Basel) 2019; 19:s19040941. [PMID: 30813385 PMCID: PMC6413131 DOI: 10.3390/s19040941] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/15/2019] [Accepted: 02/15/2019] [Indexed: 01/25/2023]
Abstract
This paper presents the application of zinc/aluminium-layered double hydroxide-quinclorac (Zn/Al-LDH-QC) as a modifier of multiwalled carbon nanotubes (MWCNT) paste electrode for the determination of bisphenol A (BPA). The Zn/Al-LDH-QC/MWCNT morphology was examined by a transmission electron microscope and a scanning electron microscope. Electrochemical impedance spectroscopy was utilized to investigate the electrode interfacial properties. The electrochemical responses of the modified electrode towards BPA were thoroughly evaluated by using square-wave voltammetry technique. The electrode demonstrated three linear plots of BPA concentrations from 3.0 × 10−8–7.0 × 10−7 M (R2 = 0.9876), 1.0 × 10−6–1.0 × 10−5 M (R2 = 0.9836) and 3.0 × 10−5–3.0 × 10−4 M (R2 = 0.9827) with a limit of detection of 4.4 × 10−9 M. The electrode also demonstrated good reproducibility and stability up to one month. The presence of several metal ions and organic did not affect the electrochemical response of BPA. The electrode is also applicable for BPA determination in baby bottle and mineral water samples with a range of recovery between 98.22% and 101.02%.
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Affiliation(s)
- Rahadian Zainul
- Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Negeri Padang, West Sumatera 25171, Indonesia.
| | - Nurashikin Abd Azis
- Department of Chemistry, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
| | - Illyas Md Isa
- Department of Chemistry, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
- Nanotechnology Research Centre, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
| | - Norhayati Hashim
- Department of Chemistry, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
- Nanotechnology Research Centre, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
| | - Mohamad Syahrizal Ahmad
- Department of Chemistry, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
- Nanotechnology Research Centre, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
| | - Mohamad Idris Saidin
- Department of Chemistry, Faculty of Science and Mathemathics, Universiti Pendidikan Sultan Idris, Tanjong Malim 35900, Perak, Malaysia.
| | - Siriboon Mukdasai
- Department of Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
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20
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Masibi KK, Fayemi OE, Adekunle AS, Sherif ESM, Ebenso EE. Electrocatalysis of Lindane Using Antimony Oxide Nanoparticles Based-SWCNT/PANI Nanocomposites. Front Chem 2018; 6:423. [PMID: 30298128 PMCID: PMC6160894 DOI: 10.3389/fchem.2018.00423] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 08/24/2018] [Indexed: 11/24/2022] Open
Abstract
This work describes the chemical synthesis of antimony oxide nanoparticles (AONPs), polyaniline (PANI), acid functionalized single-walled carbon nanotubes (fSWCNTs), and the nanocomposite (AONP-PANI-SWCNT) as catalyst for the trace detection of lindane. Successful synthesis of the nanomaterials was confirmed by Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, x-ray diffraction (XRD) spectroscopy, and scanning electron microscopy (SEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for investigating the electrochemical behavior of the modified electrodes in the ferrocyanide/ferricyanide ([Fe(CN)6]4−/[Fe(CN)6]3−) redox probe. GCE-AONP-PANI-SWCNT exhibited faster electron transport properties as well as higher electroactivity as compared to bare-GCE, GCE-AONPs, GCE-PANI, and GCE-SWCNT electrodes. Electrocatalytic studies further showed that GCE-AONP-PANI-SWCNT modified electrode was stable (after 20 scans) with only a small current drop in lindane (0.57%). The GCE-AONP-PANI-SWCNT electrode with low detection limit of 2.01 nM performed better toward the detection of lindane as compared to other studies in literature. The GCE-AONP-PANI-SWCNT electrode is highly selective toward the detection of lindane in the presence of various organic and inorganic interfering species. Real sample analysis of river water and tap water samples using the developed sensor gave satisfactory percentage recoveries therefore confirming the potential of the proposed sensor for practical application.
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Affiliation(s)
- Kgotla K Masibi
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa.,Material Science Innovation and Modelling Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa
| | - Omolola E Fayemi
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa.,Material Science Innovation and Modelling Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa
| | - Abolanle S Adekunle
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa.,Material Science Innovation and Modelling Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa.,Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - El-Sayed M Sherif
- Center of Excellence for Research in Engineering Materials, King Saud University, Al-Riyadh, Saudi Arabia.,Electrochemistry and Corrosion Laboratory, Department of Physical Chemistry, National Research Centre, Cairo, Egypt
| | - Eno E Ebenso
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa.,Material Science Innovation and Modelling Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa
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21
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Apetrei IM, Apetrei C. Highly sensitive voltamperometric determination of pyritinol using carbon nanofiber/gold nanoparticle composite screen-printed carbon electrode. Int J Nanomedicine 2017; 12:5177-5188. [PMID: 28860746 PMCID: PMC5560415 DOI: 10.2147/ijn.s138978] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
A novel and highly sensitive electrochemical method for the detection of pyritinol in pharmaceutical products and serum samples has been accomplished based on voltamperometric response of pyritinol in carbon nanofiber-gold nanoparticle (CNF-GNP)-modified screen-printed carbon electrode (SPCE). The electrochemical response of pyritinol to CNF-GNP-modified SPCE was studied by cyclic voltammetry and square-wave voltammetry (SWV). Under optimized working conditions, the novel sensor shows excellent voltamperometric response toward pyritinol. The SWV study shows significantly enhanced electrochemical response for pyritinol in CNF-GNP-modified SPCE providing high sensitivity to the novel sensor for pyritinol detection. The peak current for pyritinol is found to be linear with the concentration in the range 1.0×10-8-5.0×10-5 M with a detection limit of 6.23×10-9 M using SWV as the detection method. The viability of the new developed sensor for the analytical purposes was studied by performing experiments on various commercial pharmaceutical products and blood serum samples, which yielded adequate recoveries of pyritinol. The novel electrochemical sensor provides high sensitivity, enhanced selectivity, good reproducibility and practical applicability.
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Affiliation(s)
- Irina Mirela Apetrei
- Department of Pharmaceutical Sciences, Medical and Pharmaceutical Research Center, Faculty of Medicine and Pharmacy
| | - Constantin Apetrei
- Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, "Dunarea de Jos" University of Galati, Galati, Romania
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22
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Arroyo-Currás N, Somerson J, Vieira PA, Ploense KL, Kippin TE, Plaxco KW. Real-time measurement of small molecules directly in awake, ambulatory animals. Proc Natl Acad Sci U S A 2017; 114:645-50. [PMID: 28069939 DOI: 10.1073/pnas.1613458114] [Citation(s) in RCA: 238] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The development of a technology capable of tracking the levels of drugs, metabolites, and biomarkers in the body continuously and in real time would advance our understanding of health and our ability to detect and treat disease. It would, for example, enable therapies guided by high-resolution, patient-specific pharmacokinetics (including feedback-controlled drug delivery), opening new dimensions in personalized medicine. In response, we demonstrate here the ability of electrochemical aptamer-based (E-AB) sensors to support continuous, real-time, multihour measurements when emplaced directly in the circulatory systems of living animals. Specifically, we have used E-AB sensors to perform the multihour, real-time measurement of four drugs in the bloodstream of even awake, ambulatory rats, achieving precise molecular measurements at clinically relevant detection limits and high (3 s) temporal resolution, attributes suggesting that the approach could provide an important window into the study of physiology and pharmacokinetics.
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23
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Biala K, Sedova A, Flechsig GU. Sequence and Temperature Influence on Kinetics of DNA Strand Displacement at Gold Electrode Surfaces. ACS Appl Mater Interfaces 2015; 7:19948-19959. [PMID: 26302819 DOI: 10.1021/acsami.5b04435] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding complex contributions of surface environment to tethered nucleic acid sensing experiments has proven challenging, yet it is important because it is essential for interpretation and calibration of indispensable methods, such as microarrays. We investigate the effects of DNA sequence and solution temperature gradients on the kinetics of strand displacement at heated gold wire electrodes, and at gold disc electrodes in a heated solution. Addition of a terminal double mismatch (toehold) provides a reduction in strand displacement energy barriers sufficient to probe the secondary mechanisms involved in the hybridization process. In four different DNA capture probe sequences (relevant for the identification of genetically modified maize MON810), all but one revealed a high activation energy up to 200 kJ/mol during hybridization, that we attribute to displacement of protective strands by capture probes. Protective strands contain 4 to 5 mismatches to ease their displacement by the surface-confined probes at the gold electrodes. A low activation energy (30 kJ/mol) was observed for the sequence whose protective strand contained a toehold and one central mismatch, its kinetic curves displayed significantly different shapes, and we observed a reduced maximum signal intensity as compared to other sequences. These findings point to potential sequence-related contributions to oligonucleotide diffusion influencing kinetics. Additionally, for all sequences studied with heated wire electrodes, we observed a 23 K lower optimal hybridization temperature in comparison with disc electrodes in heated solution, and greatly reduced voltammetric signals after taking into account electrode surface area. We propose that thermodiffusion due to temperature gradients may influence both hybridization and strand displacement kinetics at heated microelectrodes, an explanation supported by computational fluid dynamics. DNA assays with surface-confined capture probes and temperature gradients should not neglect potential influences of thermodiffusion as well as sequence-related effects. Furthermore, studies attempting to characterize surface-tethered environments should consider thermodiffusion if temperature gradients are involved.
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Affiliation(s)
- Katarzyna Biala
- Department of Chemistry, University at Albany, SUNY , 1400 Washington Avenue, Albany, New York 12222, United States
- Department of Chemistry, University of Rostock , A.-Einstein-Str. 3a, D-18059 Rostock, Germany
| | - Ada Sedova
- Department of Chemistry, University at Albany, SUNY , 1400 Washington Avenue, Albany, New York 12222, United States
| | - Gerd-Uwe Flechsig
- Department of Chemistry, University at Albany, SUNY , 1400 Washington Avenue, Albany, New York 12222, United States
- Department of Chemistry, University of Rostock , A.-Einstein-Str. 3a, D-18059 Rostock, Germany
- Gensoric GmbH, Schillingallee 68, D-18057 Rostock, Germany
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24
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Kariuki J, Ervin E, Olafson C. Development of a Novel, Low-Cost, Disposable Wooden Pencil Graphite Electrode for Use in the Determination of Antioxidants and Other Biological Compounds. Sensors (Basel) 2015; 15:18887-900. [PMID: 26263997 DOI: 10.3390/s150818887] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 07/18/2015] [Accepted: 07/27/2015] [Indexed: 11/28/2022]
Abstract
The development of portable sensors that can be used outside the lab is an active area of research in the electroanalytical field. A major focus of such research is the development of low-cost electrodes for use in these sensors. Current electrodes, such as glassy-carbon electrodes (GCEs), are costly and require time-consuming preparation. Alternatives have been proposed, including mechanical pencil-lead electrodes (MPEs). However, MPEs themselves possess numerous drawbacks, particularly structural fragility. In this paper, we present a novel pencil-graphite electrode (PGE) fabricated from a regular HB#2 pencil. This PGE is a simple, disposable, extremely low-cost alternative to GCEs ($0.30 per PGE, vs. $190 + per GCE), and possesses the structural stability that MPEs lack. PGEs were characterized by square-wave voltammetry of ferricyanide, gallic acid, uric acid, dopamine, and several foodstuffs. In all cases, PGEs demonstrated sensitivities comparable or superior to those of the GCE and MPE (LOD = 5.62 × 10−4 M PGE, 4.80 × 10−4 M GCE, 2.93 × 10−4 M MPE). Signal areas and peak heights were typically four to ten times larger for the PGE relative to the GCE.
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Baciu A, Ardelean M, Pop A, Pode R, Manea F. Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode. Sensors (Basel) 2015; 15:14526-38. [PMID: 26102487 DOI: 10.3390/s150614526] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/22/2015] [Indexed: 11/17/2022]
Abstract
This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD) electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix.
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Remes A, Pop A, Manea F, Baciu A, Picken SJ, Schoonman J. Electrochemical determination of pentachlorophenol in water on a multi-wall carbon nanotubes-epoxy composite electrode. Sensors (Basel) 2012; 12:7033-46. [PMID: 22969335 DOI: 10.3390/s120607033] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 04/18/2012] [Accepted: 04/26/2012] [Indexed: 11/17/2022]
Abstract
The aim of this study was the preparation, characterization, and application of a multi-wall carbon nanotubes-epoxy composite electrode (MWCNT-EP) with 25%, wt. MWCNTs loading for the voltammetric/amperometric determination of pentachlorophenol (PCP) in aqueous solutions. The structural and morphological aspects of the MWCNT-EP composite electrode were examined by scanning electron microscopy. The electrical properties were characterized by direct-current conductivity measurements in relation with the percolation threshold. The electrochemical behavior of PCP at the MWCNT-EP composite electrode was investigated using cyclic voltammetry in 0.1 M Na2SO4 supporting electrolyte in order to establish the parameters for amperometric/voltammetric determination of PCP. The linear dependence of current vs. PCP concentrations was reached in a wide concentration range from 0.2 to 12 μM PCP using cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry, chronoamperometry, and multiple-pulsed amperometry techniques. The best electroanalytical performances of this composite electrode were achieved using a pre-concentration/square-wave voltammetric technique and also multiple-pulsed amperometry techniques envisaging the practical applications. The ease of preparation, high sensitivity, and stability of this composite electrode should open novel avenues and applications for fabricating robust sensors for detection of many important species.
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Kumar S, Vicente-Beckett V. Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry. Beilstein J Nanotechnol 2012; 3:388-396. [PMID: 23016143 PMCID: PMC3388363 DOI: 10.3762/bjnano.3.45] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 04/26/2012] [Indexed: 06/01/2023]
Abstract
Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA) by square-wave voltammetry (SWV). The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified) electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd). Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047-5.0 mmol/L) and displayed good linearity (R(2) = 0.994). The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96-104%) with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99-104%). The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC) with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05).
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Affiliation(s)
- Sushil Kumar
- Central Queensland University, Centre for Plant and Water Science, Rockhampton, Queensland 4702, Australia
| | - Victoria Vicente-Beckett
- Central Queensland University, Centre for Environmental Management, Rockhampton, Queensland 4702, Australia
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