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Motswainyana WM, Ojwach SO, Onani MO, Iwuoha EI, Darkwa J. Novel hemi-labile pyridyl-imine palladium complexes: Synthesis, molecular structures and reactions with ethylene. Polyhedron 2011. [DOI: 10.1016/j.poly.2011.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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van Wyk VD, Baker PGL, Waryo T, Iwuoha EI, O'Sullivan C. Electrochemical Evaluation of a Novel Boron Doped Diamond (BDD) Material for Application as Potential Electrochemical Capacitor. ANAL LETT 2011. [DOI: 10.1080/00032719.2010.539735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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West N, Baker PGL, Arotiba OA, Hendricks NR, Baleg AA, Waryo TT, Ngece RF, Iwuoha EI, O'Sullivan C. Overoxidized Polypyrrole Incorporated with Gold Nanoparticles as Platform for Impedimetric Anti-Transglutaminase Immunosensor. ANAL LETT 2011. [DOI: 10.1080/00032719.2010.539739] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Masikini M, Waryo TT, Baker PGL, Ngqongwa LV, Williams AR, Iwuoha EI. Hydroxy-Iron/β-cyclodextrin-Film Amperometric Sensor for the Endocrine Disruptor Substance Bisphenol-A in an Aqueous Medium with Reduced Fouling Effects. ANAL LETT 2011. [DOI: 10.1080/00032719.2010.539741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Nomngongo PN, Ngila JC, Nyamori VO, Songa EA, Iwuoha EI. Determination of Selected Heavy Metals Using Amperometric Horseradish Peroxidase (HRP) Inhibition Biosensor. ANAL LETT 2011. [DOI: 10.1080/00032719.2010.539738] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Ndangili PM, Jijana AM, Baker PG, Iwuoha EI. 3-Mercaptopropionic acid capped ZnSe quantum dot-cytochrome P450 3A4 enzyme biotransducer for 17β-estradiol. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2010.12.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Baleg AAA, Jahed NM, Arotiba OA, Mailu SN, Hendricks NR, Baker PG, Iwuoha EI. Synthesis and characterization of poly(propylene imine) dendrimer – Polypyrrole conducting star copolymer. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2010.12.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Somerset VS, Hernandez LH, Iwuoha EI. Stripping voltammetric measurement of trace metal ions using screen-printed carbon and modified carbon paste electrodes on river water from the Eerste-Kuils River System. J Environ Sci Health A Tox Hazard Subst Environ Eng 2011; 46:17-32. [PMID: 21104492 DOI: 10.1080/10934529.2011.526075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Screen-printed carbon electrodes (SPCEs) and carbon paste electrodes (CPEs) were prepared as "mercury-free" electrochemical sensors for the determination of trace metal ions in aqueous solutions. SPCEs were coated with conducting polymer layers of either polyaniline (PANI), or polyaniline-poly(2,2'-dithiodianiline) (PANI-PDTDA). Furthermore, CPEs containing electroactive compounds with reactivity towards metal ions were employed to obtain enhanced selectivity. Optimised experimental conditions for Hg(2+), Pb(2+), Ni(2+) and Cd(2+) determination included the supporting electrolyte concentration, deposition potential (E(d)) and accumulation time (t(acc)). For the modified carbon paste sensors (MCPEs) it was found that -400 mV is an adequate deposition potential and an accumulation time of 120 s was adequate for the determination using the different constructed electrodes. Initial results showed linearity in the examined concentration range between 1 × 10(-9) M and 1 × 10(-6) M using the SPCE/PANI-PDTDA sensor on laboratory prepared standard solutions, while good selectivity for the different metal ions were obtained. Furthermore, the limit of detection (LOD) was determined for each of the sensors and for the SPCE/PANI-PDTDA sensor it was found to be 2.2 × 10(-13) M, while for the SPCE/PANI sensor the LOD was determined to be 8.4 × 10(-11) M. The MCPE sensors also showed good linearity between the concentration range of 1 × 10(-3) to 1 × 10(-9) M. The LOD values for the various MCPE sensors, were found to be Hg(II) - 1.3 × 10(-7) M; Cd(II) - 2.9 × 10(-7) M; Ni(II) - 3.2 × 10(-7) M; and Pb(II) - 1.7 × 10(-7) M for the CPE/PANI-PDTDA sensor. For the CPE/PANI sensor the LOD values were Hg(II) - 1.5 × 10(-5) M; Cd(II) - 8.6 × 10(-7) M; Ni(II) - 9.5 × 10(-7) M; and Pb(II) - 1.3 × 10(-6) M. For the CPE/MBT sensor the LOD values were Hg(II) - 3.8 × 10(-5) M; Cd(II) - 1.4 × 10(-6) M; Ni(II) - 1 × 10(-6) M; and Pb(II) - 6.3 × 10(-5) M. Very low detection was obtained for the SPCE/PANI-PDTDA sensor in Hg(2+) determination, while the MCPE sensors delivered sensitive simultaneous detection for Hg(2+), Pb(2+), Ni(2+) and Cd(2+) metal ions.
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Affiliation(s)
- Vernon S Somerset
- NRE, Council for Scientific and Industrial Research (CSIR), Stellenbosch, South Africa.
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Fatoba OO, Petrik LF, Gitari WM, Iwuoha EI. Fly ash-brine interactions: removal of major and trace elements from brine. J Environ Sci Health A Tox Hazard Subst Environ Eng 2011; 46:1648-1666. [PMID: 22126135 DOI: 10.1080/10934529.2011.623647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fly ash and brine contain major and trace elements such as Na, Cl, Ca, SO(4), K, Mg, P, Si, Al, Fe, Mn, Cr, V and Ti in significant quantities. This study focuses on the leachability of species from fly ash and the removal of major and trace species from brine as the two waste streams interact. Another objective is to evaluate the effect of the interactions on the brine quality. Batch reaction tests were carried out on two different fly ashes and brine at different L/S ratios and different reaction times, and the supernatant analysed for major and trace species. Chemical analysis revealed that the unreacted brine solution contained high concentration of species such as Na, K, Ca, Mg, Cl and SO(4), while species such as As, Ba, Cd, Co, Cr, Mn, Pb and Ti were present in trace quantities. Analysis of the supernatants after the batch reaction tests (fly ash-brine interaction experiments) revealed that major species such as Na, Mg, Cl and SO(4), and trace elements such as As, Co, Pb, Zn, Ni and Cu were significantly removed from the brine solution while Ca, Ba, Sr, Cr and Mo were leached into the brine solution from the fly ashes. The removal of species from the brine solution was most prominent at L/S ratio 1:1. This indicates that the L/S ratio of the ash-brine system has a significant effect on the release of species from fly ash or the removal of species from brine solution. The final pH of the fly ash-brine solutions and the contact times were also observed to have a significant effect on the leaching from fly ash as well as the removal of major and trace species from the brine. The study also showed that some contaminant species can be removed from brine solution using fly ash.
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Affiliation(s)
- Ojo O Fatoba
- Environmental and Nano Sciences Research Group, Chemistry Department, University of the Western Cape, Bellville, South Africa.
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61
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Mailu SN, Waryo TT, Ndangili PM, Ngece FR, Baleg AA, Baker PG, Iwuoha EI. Determination of anthracene on Ag-Au alloy nanoparticles/overoxidized-polypyrrole composite modified glassy carbon electrodes. Sensors (Basel) 2010; 10:9449-65. [PMID: 22163419 PMCID: PMC3230969 DOI: 10.3390/s101009449] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 08/31/2010] [Accepted: 09/10/2010] [Indexed: 11/16/2022]
Abstract
A novel electrochemical sensor for the detection of anthracene was prepared by modifying a glassy carbon electrode (GCE) with over-oxidized polypyrrole (PPyox) and Ag-Au (1:3) bimetallic nanoparticles (Ag-AuNPs). The composite electrode (PPyox/Ag-AuNPs/GCE) was prepared by potentiodynamic polymerization of pyrrole on GCE followed by its overoxidation in 0.1 M NaOH. Ag-Au bimetallic nanoparticles were chemically prepared by the reduction of AgNO3 and HAuCl4 using C6H5O7Na3 as the reducing agent as well as the capping agent and then immobilized on the surface of the PPyox/GCE. The nanoparticles were characterized by UV-visible spectroscopy technique which confirmed the homogeneous formation of the bimetallic alloy nanoparticles. Transmission electron microscopy showed that the synthesized bimetallic nanoparticles were in the range of 20–50 nm. The electrochemical behaviour of anthracene at the PPyox/Ag-AuNPs/GCE with Ag: Au atomic ratio 25:75 (1:3) exhibited a higher electrocatalytic effect compared to that observed when GCE was modified with each constituent of the composite (i.e., PPyox, Ag-AuNPs) and bare GCE. A linear relationship between anodic current and anthracene concentration was attained over the range of 3.0 × 10−6 to 3.56 × 10−4 M with a detection limit of 1.69 × 10−7 M. The proposed method was simple, less time consuming and showed a high sensitivity.
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Affiliation(s)
- Stephen N Mailu
- Sensor Lab, Department of Chemistry, University of Western Cape, Bellville, 7535, South Africa.
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62
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Onani MO, Motswainyana WM, Iwuoha EI, Darkwa J, Lalancette RA. Chlorido{N-[2-(diphenylphosphanyl)benz-ylidene]-2-(2-thienyl)ethanamine-κN,P}methylpalladium(II) dichloromethane hemisolvate. Acta Crystallogr Sect E Struct Rep Online 2010; 66:m688. [PMID: 21579327 PMCID: PMC2979533 DOI: 10.1107/s1600536810017824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 05/14/2010] [Indexed: 11/10/2022]
Abstract
In the title compound, [Pd(CH(3))Cl(C(25)H(22)NPS)]·0.5C(2)H(2)Cl(2), the Pd(II) atom is coordinated by the N,P-bidentate ligand, a methyl group and a chloride ion, generating a distorted square-planar PdCClNS coordination geometry, with the N and Cl atoms trans. The thio-phene ring is equally disordered over two orientations and the dichloro-methane solvent mol-ecule is disordered about an inversion centre.
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63
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Ndangili PM, Arotiba OA, Baker PG, Iwuoha EI. A potential masking approach in the detection of dopamine on 3-mercaptopropionic acid capped ZnSe quantum dots modified gold electrode in the presence of interferences. J Electroanal Chem (Lausanne) 2010. [DOI: 10.1016/j.jelechem.2010.03.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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64
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Arotiba OA, Owino JH, Baker PG, Iwuoha EI. Electrochemical impedimetry of electrodeposited poly(propylene imine) dendrimer monolayer. J Electroanal Chem (Lausanne) 2010. [DOI: 10.1016/j.jelechem.2009.10.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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65
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Al-Ahmed A, Ndangili PM, Jahed N, Baker PGL, Iwuoha EI. Polyester sulphonic Acid interstitial nanocomposite platform for peroxide biosensor. Sensors (Basel) 2009; 9:9965-76. [PMID: 22303157 PMCID: PMC3267205 DOI: 10.3390/s91209965] [Citation(s) in RCA: 7] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 11/25/2009] [Accepted: 12/07/2009] [Indexed: 12/04/2022]
Abstract
A novel enzyme immobilization platform was prepared on a platinum disk working electrode by polymerizing aniline inside the interstitial pores of polyester sulphonic acid sodium salt (PESA). Scanning electron microscopy study showed the formation of homogeneous sulphonated polyaniline (PANI) nanotubes (∼90 nm) and thermogravimetric analysis (TGA) confirmed that the nanotubes were stable up to 230 °C. The PANI:PESA nanocomposite showed a quasi-reversible redox behaviour in phosphate buffer saline. Horseradish peroxidase (HRP) was immobilized on to this modified electrode for hydrogen peroxide detection. The biosensor gave a sensitivity of 1.33 μA (μM)-1 and a detection limit of 0.185 μM for H2O2. Stability experiments showed that the biosensor retained more than 64% of its initial sensitivity over four days of storage at 4 °C.
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Affiliation(s)
- Amir Al-Ahmed
- SensorLab, Department of Chemistry, University of Western Cape, Bellville, 7535, Cape Town, South Africa; E-Mails: (A.A.-A.); (P.M.N.); (N.J.); (E.I.I.)
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66
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Songa EA, Arotiba OA, Owino JHO, Jahed N, Baker PGL, Iwuoha EI. Electrochemical detection of glyphosate herbicide using horseradish peroxidase immobilized on sulfonated polymer matrix. Bioelectrochemistry 2009; 75:117-23. [PMID: 19336272 DOI: 10.1016/j.bioelechem.2009.02.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 01/09/2009] [Accepted: 02/25/2009] [Indexed: 11/18/2022]
Abstract
This paper describes the use of horseradish peroxidase (HRP) based biosensor for novel detection of glyphosate herbicide. The biosensor was prepared by electrochemically depositing poly(2,5-dimethoxyaniline) (PDMA) doped with poly(4-styrenesulfonic acid) (PSS) onto the surface of a gold electrode followed by electrostatic attachment of the enzyme HRP onto the PDMA-PSS composite film. Fourier transform infrared (FTIR) and UV-Vis spectrometry inferred that HRP was not denatured during its immobilization on PDMA-PSS composite film. The biosensing principle was based on the determination of the cathodic responses of the immobilized HRP to H(2)O(2), before and after incubation in glyphosate standard solutions. Glyphosate inhibited the activity of HRP causing a decrease in its response to H(2)O(2). The determination of glyphosate was achieved in the range of 0.25-14.0 microg L(-1) with a detection limit of 1.70 microg L(-1). The apparent Michaelis-Menten constant (calculated for the HRP/PDMA-PSS biosensor in the presence and absence of glyphosate was found to be 7.73 microM and 7.95 microM respectively.
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Affiliation(s)
- Everlyne A Songa
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X 17, Bellville, 7535, South Africa
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Hendricks NR, Waryo TT, Arotiba O, Jahed N, Baker PG, Iwuoha EI. Microsomal cytochrome P450-3A4 (CYP3A4) nanobiosensor for the determination of 2,4-dichlorophenol—An endocrine disruptor compound. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2008.09.073] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Songa EA, Somerset VS, Waryo T, Baker PGL, Iwuoha EI. Amperometric nanobiosensor for quantitative determination of glyphosate and glufosinate residues in corn samples. PURE APPL CHEM 2009. [DOI: 10.1351/pac-con-08-01-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study presents a simple, sensitive, rapid, and low-cost amperometric method for direct and quantitative determination of glyphosate and glufosinate herbicides. Electrochemical synthesis and characterization of poly(2,5-dimethoxyaniline)-poly(4-styrenesulfonic acid) (PDMA-PSS) nanoparticles was achieved by cyclic voltammetry (CV) and scanning electron microscopy (SEM). The nanobiosensor was constructed by immobilizing the enzyme horseradish peroxidase (HRP) electrostatically onto the surface of a rotating gold disk electrode modified with PDMA-PSS nanoparticles. The biosensing principle was based on determination of the sensor response to glyphosate and glufosinate by amperometric methods. Hydrogen peroxide (H2O2) was used to measure activity of the enzyme before injection of the herbicides into the electrolyte solution. The enzyme electrode was stable for a long period of time and was used for over 60 measurements. Glyphosate and glufosinate analyses were realized on spiked corn samples within a concentration range of 2.0-78.0 μg L-1, corroborating that the nanobiosensor is sensitive enough to detect herbicides in these matrices. Based on a 20-μL sample injection volume, the detection limits were 0.1 μg L-1 (10-10 M) for both glyphosate and glufosinate without sample clean-up or preconcentration.
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Affiliation(s)
- Everlyne A. Songa
- 1SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa
| | - Vernon S. Somerset
- 1SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa
| | - Tesfaye Waryo
- 1SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa
| | - Priscilla G. L. Baker
- 1SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa
| | - Emmanuel I. Iwuoha
- 1SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa
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69
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Owino JHO, Arotiba OA, Hendricks N, Songa EA, Jahed N, Waryo TT, Ngece RF, Baker PGL, Iwuoha EI. Electrochemical Immunosensor Based on Polythionine/Gold Nanoparticles for the Determination of Aflatoxin B₁. Sensors (Basel) 2008; 8:8262-8274. [PMID: 27873987 PMCID: PMC3791018 DOI: 10.3390/s8128262] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [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: 09/19/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 11/24/2022]
Abstract
An aflatoxin B₁ (AFB₁) electrochemical immunosensor was developed by the immobilisation of aflatoxin B₁-bovine serum albumin (AFB₁-BSA) conjugate on a polythionine (PTH)/gold nanoparticles (AuNP)-modified glassy carbon electrode (GCE). The surface of the AFB₁-BSA conjugate was covered with horseradish peroxidase (HRP), in order to prevent non-specific binding of the immunosensors with ions in the test solution. The AFB₁ immunosensor exhibited a quasi-reversible electrochemistry as indicated by a cyclic voltammetric (CV) peak separation (ΔEp) value of 62 mV. The experimental procedure for the detection of AFB₁ involved the setting up of a competition between free AFB₁ and the immobilised AFB₁-BSA conjugate for the binding sites of free anti-aflatoxin B₁ (anti-AFB₁) antibody. The immunosensor's differential pulse voltammetry (DPV) responses (peak currents) decreased as the concentration of free AFB₁ increased within a dynamic linear range (DLR) of 0.6 - 2.4 ng/mL AFB₁ and a limit of detection (LOD) of 0.07 ng/mL AFB₁. This immunosensing procedure eliminates the need for enzyme-labeled secondary antibodies normally used in conventional ELISA-based immunosensors.
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Affiliation(s)
- Joseph H O Owino
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Omotayo A Arotiba
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Nicolette Hendricks
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Everlyne A Songa
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Nazeem Jahed
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Tesfaye T Waryo
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Rachel F Ngece
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Priscilla G L Baker
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa.
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Ignaszak A, Hendricks N, Waryo T, Songa E, Jahed N, Ngece R, Al-Ahmed A, Kgarebe B, Baker P, Iwuoha EI. Novel therapeutic biosensor for indinavir-a protease inhibitor antiretroviral drug. J Pharm Biomed Anal 2008; 49:498-501. [PMID: 19056199 DOI: 10.1016/j.jpba.2008.10.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 10/19/2008] [Accepted: 10/20/2008] [Indexed: 11/26/2022]
Abstract
An amperometric drug metabolism biosensor consisting of cytochrome P450-3A4 (CYP3A4) encapsulated in a didodecyldimethylammonium bromide (DDAB) vesicular system on a Pt disk electrode was developed for the determination of indinavir, a protease inhibitor antiretroviral drug. Cyclic, square wave and pulse voltammetric responses of the bioelectrode showed quasi-reversible electrochemistry of the Fe(3+)/Fe(2+) redox species of the heme thiolate CYP3A4 enzyme under aerobic and anaerobic conditions. The biosensor exhibited excellent response to indinavir with a detection limit and response time of 6.158 x 10(-2)mgL(-1), and 40s, respectively. The detection limit is well below the plasma concentration of indinavir (8h after intake) which range from 0.13 to 8.6mgL(-1).
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Affiliation(s)
- A Ignaszak
- Department of Chemistry, University of Western Cape, Bellville, Cape Town 7535, South Africa
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Arotiba OA, Ignaszak A, Malgas R, Al-Ahmed A, Baker PG, Mapolie SF, Iwuoha EI. An electrochemical DNA biosensor developed on novel multinuclear nickel(II) salicylaldimine metallodendrimer platform. Electrochim Acta 2007. [DOI: 10.1016/j.electacta.2007.08.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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72
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Owino JHO, Ignaszak A, Al-Ahmed A, Baker PGL, Alemu H, Ngila JC, Iwuoha EI. Modelling of the impedimetric responses of an aflatoxin B1 immunosensor prepared on an electrosynthetic polyaniline platform. Anal Bioanal Chem 2007; 388:1069-74. [PMID: 17563886 DOI: 10.1007/s00216-007-1333-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 04/23/2007] [Accepted: 04/30/2007] [Indexed: 10/23/2022]
Abstract
Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants or plant products. An electrochemical immunosensor for the determination of aflatoxin B(1) (AFB(1)) was developed with AFB(1)antibody (AFB(1)-Ab) immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis shows that the electron transfer resistances of the Pt/PANi-PSSA electrode, the Pt/PANi-PSSA/AFB(1)-Ab immunosensor and Pt/PANi-PSSA/AFB(1)-Ab incubated in bovine serum albumin (BSA) were 0.458, 720 and 1,066 kOmega, respectively. These results indicate that electrochemical impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron transfer resistance associated with the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer resistance increased from 0.458 kOmega for the Pt/PANi-PSSA electrode to 1,066 kOmega for the Pt/PANi-PSSA/AFB(1)-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier. The AFB(1) immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 kOmega L/mg.
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Affiliation(s)
- Joseph H O Owino
- Sensor Research Laboratory, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, Cape Town, South Africa
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Somerset VS, Klink MJ, Baker PGL, Iwuoha EI. Acetylcholinesterase-polyaniline biosensor investigation of organophosphate pesticides in selected organic solvents. J Environ Sci Health B 2007; 42:297-304. [PMID: 17454383 DOI: 10.1080/03601230701229288] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The behavior of an amperometric organic-phase biosensor consisting of a gold electrode modified first with a mercaptobenzothiazole self-assembled monolayer, followed by electropolymerization of polyaniline in which acetylcholinesterase as enzyme was immobilized, has been developed and evaluated for organophosphorous pesticide detection. The voltammetric results have shown that the formal potential shifts anodically as the Au/MBT/PANI/AChE/PVAc thick-film biosensor responded to acetylthiocholine substrate addition under anaerobic conditions in selected organic solvent media containing 2% v/v 0.05 M phosphate buffer, 0.1 M KCl (pH 7.2) solution. Detection limits in the order of 0.147 ppb for diazinon and 0.172 ppb for fenthion in acetone-saline phosphate buffer solution, and 0.180 ppb for diazinon and 0.194 ppb for fenthion in ethanol-saline phosphate buffer solution has been achieved.
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Affiliation(s)
- Vernon S Somerset
- Department of Chemistry, University of the Western Cape, Bellville, South Africa
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74
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Somerset VS, Klink MJ, Sekota MMC, Baker PGL, Iwuoha EI. Polyaniline‐Mercaptobenzothiazole Biosensor for Organophosphate and Carbamate Pesticides. ANAL LETT 2006. [DOI: 10.1080/00032710600713834] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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75
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Iwuoha EI, Mavundla SE, Somerset VS, Petrik LF, Klink MJ, Sekota M, Bakers P. Electrochemical and Spectroscopic Properties of Fly Ash–Polyaniline Matrix Nanorod Composites. Mikrochim Acta 2006. [DOI: 10.1007/s00604-006-0584-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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76
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Iwuoha EI, Smyth MR. Reactivities of organic phase biosensors: 6. Square-wave and differential pulse studies of genetically engineered cytochrome P450(cam) (CYP101) bioelectrodes in selected solvents. Biosens Bioelectron 2003; 18:237-44. [PMID: 12485770 DOI: 10.1016/s0956-5663(02)00180-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cytochrome P450(cam) (CYP101) bioelectrodes suitable for application in organic phases were prepared from genetically engineered CYP101 and vesicular dispersions of didodecyldimethylammonium bromide. The amperometric biosensor system was characterised under anaerobic conditions by cyclic and square-wave voltammetric methods. Cyclic- and square-wave-voltammetry studies showed that the biosensors exhibited direct reversible electron transfer between the haem iron atom and the glassy carbon electrode surface. The formal redox potential estimated for the electrode in acetonitrile was -380 mV/Ag-AgCl. The formal potential shifted anodically as the organic phase biosensor responded irreversibly to substrate (camphor) under anaerobic and aerobic conditions in acetonitrile. Differential pulse analysis of the reactivities of the CYP101 enzyme electrode confirmed the square-wave voltammetry result, which showed that the binding of substrate decreased the redox potential necessary for initiating the monooxygenation reaction of cytochrome P450(cam).
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Affiliation(s)
- Emmanuel I Iwuoha
- Department of Chemistry, University of Western Cape, Bellville 7535, South Africa.
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77
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Moutloali RM, Nevondo FA, Darkwa J, Iwuoha EI, Henderson W. Bimetallic nickel complexes with bridging dithiolato Schiff base ligands: synthesis, mass spectral characterisation and electrochemistry. J Organomet Chem 2002. [DOI: 10.1016/s0022-328x(02)01626-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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78
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Iwuoha EI, Kane S, Ania CO, Smyth MR, Ortiz de Montellano PR, Fuhr U. Reactivities of Organic Phase Biosensors 3: Electrochemical Study of Cytochrome P450cam Immobilized in a Methyltriethoxysilane Sol-Gel. ELECTROANAL 2000. [DOI: 10.1002/1521-4109(200008)12:12<980::aid-elan980>3.0.co;2-f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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79
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Killard AJ, Zhang S, Zhao H, John R, Iwuoha EI, Smyth MR. Development of an electrochemical flow injection immunoassay (FIIA) for the real-time monitoring of biospecific interactions. Anal Chim Acta 1999. [DOI: 10.1016/s0003-2670(99)00611-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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80
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81
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Iwuoha EI, Joseph S, Zhang Z, Smyth MR, Fuhr U, Ortiz de Montellano PR. Drug metabolism biosensors: electrochemical reactivities of cytochrome P450cam immobilised in synthetic vesicular systems. J Pharm Biomed Anal 1998; 17:1101-10. [PMID: 9884200 DOI: 10.1016/s0731-7085(98)00076-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Biosensors containing cytochrome P450cam in a didodecyldimethylammonium bromide vesicular system were prepared by cross-linking onto a glassy carbon electrode (GCE) with glutaraldehyde in the presence of bovine serum albumin. Cyclic voltammetric responses of the sensor in air-free buffer solution showed that the sensor exhibited reversible electrochemistry due to direct electron exchange between the haem Fe(3+/2+) redox system and the GCE surface. In air-saturated solution containing camphor, the biosensor gave an irreversible electrocatalytic current which is compatible with the monooxygenation of the substrate. Steady state amperometric experiments with camphor, adamantanone and fenchone were performed with a biosensor prepared by cross-linking P450cam with glutaraldehyde onto a Pt disc electrode. The sensor was characterised by fast amperometric responses, attaining steady-state in about 20 s in a cobalt sepulchrate mediated electrochemical system. The kinetic parameters of the biosensor were analysed using the electrochemical Michaelis Menten equation. The estimated apparent Michaelis-Menten constant, Km, values for the biosensors were in the range of 1.41-3.9 mM.
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Affiliation(s)
- E I Iwuoha
- Biomedical and Environmental Sensor Technology Centre, School of Chemical Sciences, Dublin City University, Ireland
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82
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Robinson GM, Iwuoha EI, Smyth MR. Characterisation of electrosynthetic l-dopa-melanin films by electrochemical and spectroelectrochemical techniques. Electrochim Acta 1998. [DOI: 10.1016/s0013-4686(98)00096-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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83
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84
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Abstract
The effects of the water-miscible organic solvent acetonitrile on the enzymatic activity of horseradish peroxidase (HRP) and on HRP-anti-HRP binding have been investigated. Results showed that both the catalytic activity of HRP and the binding ability of the antibody were affected on increasing the concentration of the organic solvent. The activity of HRP varied with the organic composition of the solvent, indicating that the conformation of the enzyme was affected. The binding ability of the antibody also decreased significantly with an increase of the organic composition of the solvent, and in absolute acetonitrile, the activity of the antibody is about 500 times lower than that in aqueous medium. Binding reversibility experiments indicated that the antibody was not irreversibly damaged in solutions with acetonitrile composition greater than 80% and below 40%; however, an irreversible decrease in the binding was observed in solutions with an acetonitrile composition between 40 and 80%. The reduction in the binding ability is probably due to the irreversible conformation changes in the antibody.
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Affiliation(s)
- B Lu
- BEST Centre, Dublin City University, Ireland
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85
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86
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Jezkova J, Iwuoha EI, Smyth MR, Vytras K. Stabilization of an osmium bis-bipyridyl polymer-modified carbon paste amperometric glucose biosensor using polyethyleneimine. ELECTROANAL 1997. [DOI: 10.1002/elan.1140091303] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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87
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Iwuoha EI, Saenz de Villaverde D, Garcia NP, Smyth MR, Pingarron JM. Reactivities of organic phase biosensors. 2. The amperometric behaviour of horseradish peroxidase immobilised on a platinum electrode modified with an electrosynthetic polyaniline film. Biosens Bioelectron 1997. [DOI: 10.1016/s0956-5663(97)00042-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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88
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Lu B, Iwuoha EI, Smyth MR, O'Kennedy R. Development of an “electrically wired” amperometric immunosensor for the determination of biotin based on a non-diffusional redox osmium polymer film containing an antibody to the enzyme label horseradish peroxidase. Anal Chim Acta 1997. [DOI: 10.1016/s0003-2670(97)00083-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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89
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Iwuoha EI, Leister I, Miland E, Smyth MR, Ó Fágáin C. Reactivities of Organic-Phase Biosensors. 1. Enhancement of the Sensitivity and Stability of Amperometric Peroxidase Biosensors Using Chemically Modified Enzymes. Anal Chem 1997. [DOI: 10.1021/ac960889v] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Emmanuel I. Iwuoha
- Biomedical and Environmental Sensor Technology (BEST) Centre, School of Chemical Sciences, and School of Biological Sciences, Dublin City University, Dublin 9, Ireland
| | - Ingrid Leister
- Biomedical and Environmental Sensor Technology (BEST) Centre, School of Chemical Sciences, and School of Biological Sciences, Dublin City University, Dublin 9, Ireland
| | - Enda Miland
- Biomedical and Environmental Sensor Technology (BEST) Centre, School of Chemical Sciences, and School of Biological Sciences, Dublin City University, Dublin 9, Ireland
| | - Malcolm R. Smyth
- Biomedical and Environmental Sensor Technology (BEST) Centre, School of Chemical Sciences, and School of Biological Sciences, Dublin City University, Dublin 9, Ireland
| | - Ciarán Ó Fágáin
- Biomedical and Environmental Sensor Technology (BEST) Centre, School of Chemical Sciences, and School of Biological Sciences, Dublin City University, Dublin 9, Ireland
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90
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Lu B, Iwuoha EI, Smyth MR, O’Kennedy R. Development of an Amperometric Immunosensor for Horseradish Peroxidase (HRP) Involving a Non-diffusional Osmium Redox Polymer Co-immobilised With Anti-HRP Antibody. ACTA ACUST UNITED AC 1997. [DOI: 10.1039/a607313a] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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91
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Park TM, Iwuoha EI, Smyth MR, MacCraith BD. Sol–gel-based amperometric glucose biosensor incorporating an osmium redox polymer as mediator. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/ac9963300271] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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92
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Adeyoju O, Iwuoha EI, Smyth MR, Leech D. High-performance liquid chromatographic determination of phenols using a tyrosinase-based amperometric biosensor detection system. Analyst 1996. [DOI: 10.1039/an9962101885] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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93
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Adeyoju O, Iwuoha EI, Smyth MR. Kinetic characterization of the effects of organic solvents on the performance of a peroxidase-modified electrode in detecting peroxides, thiourea and ethylenethiourea. ELECTROANAL 1995. [DOI: 10.1002/elan.1140071003] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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94
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Pravda M, Adeyoju O, Iwuoha EI, Vos JG, Smyth MR, Vytras K. Amperometric glucose biosensors based on an osmium (2+/3+) redox polymer-mediated electron transfer at carbon paste electrodes. ELECTROANAL 1995. [DOI: 10.1002/elan.1140070704] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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95
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96
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Adeyoju O, Iwuoha EI, Smyth MR. Reactivities of amperometric organic phase peroxidase-modified electrodes in the presence and absence of thiourea and ethylenethiourea as inhibitors. Anal Chim Acta 1995. [DOI: 10.1016/0003-2670(94)00291-s] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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97
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Pravda M, Jungar CM, Iwuoha EI, Smyth MR, Vytras K, Ivaska A. Evaluation of amperometric glucose biosensors based on co-immobilisation of glucose oxidase with an osmium redox polymer in electrochemically generated polyphenol films. Anal Chim Acta 1995. [DOI: 10.1016/0003-2670(94)00616-t] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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98
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Iwuoha EI, Adeyoju O, Dempsey E, Smyth MR, Liu J, Wang J. Investigation of the effects of polar organic solvents on the activity of tyrosinase entrapped in a poly(ester-sulphonic acid) polymer. Biosens Bioelectron 1995. [DOI: 10.1016/0956-5663(95)96956-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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99
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McGrath MJ, Iwuoha EI, Diamond D, Smyth MR. The use of differential measurements with a glucose biosensor for interference compensation during glucose determinations by flow injection analysis. Biosens Bioelectron 1995; 10:937-43. [PMID: 8652108 DOI: 10.1016/0956-5663(95)99231-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A novel detection system for the determination of glucose in the presence of clinically important interferents, based on the use of dual sensors and flow-injection analysis (FIA), is described. The normalisation methodology involves measurement of the interference signal at a reference sensor; this signal can then be subtracted from the glucose sensor signal (post-run) to give a corrected measurement of the glucose concentration. The detection system consists of a thin layer with dual glassy carbon working electrodes. One electrode was surface modified to act as a glucose biosensor by immobilisation of glucose oxidase (GOx) (from Aspergillus niger) with 1% glutaraldehyde and bovine serum albumin. The second electrode (glucose oxidase omitted) was utilised to measure the interference signal responding only to electroactive species present in the injected sample. A computer controlled multichannel potentiostat was used for potential application and current monitoring duties. The sensor responses were saved in ASCII format to facilitate post-run analysis in Microsoft Excel. Cyclic voltammetry (CV) was utilised to investigate the manner in which the interference signal contributed to the total signal obtained at the biosensor in the presence of glucose. The kinetics parameters Imax and the apparent Michaelis-Menten constant, K'm, were calculated for the sensor operating under flow-injection conditions.
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Affiliation(s)
- M J McGrath
- School of Chemical Sciences, Dublin City University, Glasnevin, Ireland
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100
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Iwuoha EI, Smyth MR, Vos JG. Amperometric glucose sensor containing nondiffusional osmium redox centers: Analysis of organic-phase responses. ELECTROANAL 1994. [DOI: 10.1002/elan.1140061111] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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