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Emre FB, Lopes P, Ferapontova EE. Implications of FAD Electrode Reaction Kinetics for Electrocatalysis of NADH Oxidation and Development of NAD-Dependent Enzyme Electrodes. ELECTROANAL 2014. [DOI: 10.1002/elan.201400048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Campos R, Ferapontova EE. Electrochemistry of weakly adsorbed species: Voltammetric analysis of electron transfer between gold electrodes and Ru hexaamine electrostatically interacting with DNA duplexes. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.07.083] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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53
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Lopes P, Dyrnesli H, Lorenzen N, Otzen D, Ferapontova EE. Electrochemical analysis of the fibrillation of Parkinson's disease α-synuclein. Analyst 2014; 139:749-56. [DOI: 10.1039/c3an01616a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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54
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Fernandez E, Larsson JT, McLean KJ, Munro AW, Gorton L, von Wachenfeldt C, Ferapontova EE. Electron transfer reactions, cyanide and O2 binding of truncated hemoglobin from Bacillus subtilis. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.03.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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55
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Royo B, Sosna M, Asensio AC, Moran JF, Ferapontova EE. Direct electrochemistry and environmental sensing of rice hemoglobin immobilized at graphite electrodes. J Electroanal Chem (Lausanne) 2013. [DOI: 10.1016/j.jelechem.2013.06.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Lörcher S, Lopes P, Kartashov A, Ferapontova EE. Direct Bio-electrocatalysis of O2Reduction byStreptomyces coelicolorLaccase Orientated at Promoter-Modified Graphite Electrodes. Chemphyschem 2013; 14:2112-24. [DOI: 10.1002/cphc.201300069] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Indexed: 11/06/2022]
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Abi A, Ferapontova EE. Electroanalysis of single-nucleotide polymorphism by hairpin DNA architectures. Anal Bioanal Chem 2012; 405:3693-703. [PMID: 23263518 DOI: 10.1007/s00216-012-6633-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 11/27/2012] [Accepted: 12/06/2012] [Indexed: 12/21/2022]
Abstract
Genetic analysis of infectious and genetic diseases and cancer diagnostics require the development of efficient tools for fast and reliable analysis of single-nucleotide polymorphism (SNP) in targeted DNA and RNA sequences often responsible for signalling disease onset. Here, we highlight the main trends in the development of electrochemical genosensors for sensitive and selective detection of SNP that are based on hairpin DNA architectures exhibiting better SNP recognition properties compared with linear DNA probes. SNP detection by electrochemical hairpin DNA beacons is discussed, and comparative analysis of the existing SNP sensing strategies based on enzymatic and nanoparticle signal amplification schemes is presented.
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Farjami E, Campos R, Nielsen JS, Gothelf KV, Kjems J, Ferapontova EE. RNA aptamer-based electrochemical biosensor for selective and label-free analysis of dopamine. Anal Chem 2012; 85:121-8. [PMID: 23210972 DOI: 10.1021/ac302134s] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The inherent redox activity of dopamine enables its direct electrochemical in vivo analysis ( Venton , B. J.; Wightman, M. R. Anal. Chem. 2003, 75, 414A). However, dopamine analysis is complicated by the interference from other electrochemically active endogenous compounds present in the brain, including dopamine precursors and metabolites and other neurotransmitters (NT). Here we report an electrochemical RNA aptamer-based biosensor for analysis of dopamine in the presence of other NT. The biosensor exploits a specific binding of dopamine by the RNA aptamer, immobilized at a cysteamine-modified Au electrode, and further electrochemical oxidation of dopamine. Specific recognition of dopamine by the aptamer allowed a selective amperometric detection of dopamine within the physiologically relevant 100 nM to 5 μM range in the presence of competitive concentrations of catechol, epinephrine, norepinephrine, 3,4-dihydroxy-phenylalanine (L-DOPA), 3,4-dihydroxyphenylacetic acid (DOPAC), methyldopamine, and tyramine, which gave negligible signals under conditions of experiments (electroanalysis at 0.185 V vs Ag/AgCl). The interference from ascorbic and uric acids was eliminated by application of a Nafion-coated membrane. The aptasensor response time was <1 s, and the sensitivity of analysis was 62 nA μM(-1) cm(-2). The proposed design of the aptasensor, based on electrostatic interactions between the positively charged cysteamine-modified electrode and the negatively charged aptamer, may be used as a general strategy not to restrict the conformational freedom and binding properties of surface-bound aptamers and, thus, be applicable for the development of other aptasensors.
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Farjami E, Campos R, Ferapontova EE. Effect of the DNA end of tethering to electrodes on electron transfer in methylene blue-labeled DNA duplexes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:16218-16226. [PMID: 23106377 DOI: 10.1021/la3032336] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Electron transfer (ET) in redox-labeled double-stranded (ds) DNA tethered to electrodes through the alkanethiol linker at either the 3' or 5' DNA end and bearing methylene blue (MB) conjugated to the opposite end of DNA is shown to depend on the DNA end of tethering to electrodes. For 3' tethering, a nanoscale diffusion of the positively charged MB redox probe (and thus of the individual DNA molecules) to the negatively charged electrode surface provided the highest apparent diffusion and ET rates as a result of the tilting of 3'-tethered DNA (as compared to 5'-tethered DNA) versus the normal to the surface. Dynamic values of the tilting angle varied between 57 and 45° for 16-mer and 22-mer 3'-tethered DNA, and 5'-tethering was correlated with an upright orientation of DNA at the electrode surface. The values of the diffusion coefficient D(MB) corrected for tilting angles were similar for 5'- and 3'-tethered DNA and ranged between 5.4 × 10(-12) and 2.5 × 10(-12) cm(2) s(-1), whereas the ET rate constant k(ET)(dif) fit the 4.7 × 10(-6)-10.3 × 10(-6) cm s(-1) range for 22-mer and 16-mer dsDNA, respectively. Those values, when related to the nanometer (10(-7) cm) diffusion distances (the length of the studied DNA), allow relatively fast diffusion-limited ET at an apparent rate that may exceed the rate of the corresponding surface-confined ET process. This phenomenon is of particular importance for molecular electronics and electrochemical genosensor development.
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Sosna M, Bonamore A, Gorton L, Boffi A, Ferapontova EE. Direct electrochemistry and Os-polymer-mediated bioelectrocatalysis of NADH oxidation by Escherichia coli flavohemoglobin at graphite electrodes. Biosens Bioelectron 2012. [PMID: 23208089 DOI: 10.1016/j.bios.2012.10.094] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Escherichia coli flavohemoglobin (HMP), which contains one heme and one FAD as prosthetic groups and is capable of reducing O₂ by its heme at the expense of NADH oxidized at its FAD site, was electrochemically studied at graphite (Gr) electrodes. Two signals were observed in voltammograms of HMP adsorbed on Gr, at -477 and -171 mV vs. Ag|AgCl, at pH 7.4, correlating with electrochemical responses from the FAD and heme domains, respectively. The electron transfer rate constant for ET reaction between FAD of HMP and the electrode was estimated to be 83 s⁻¹. Direct bioelectrocatalytic oxidation of NADH by HMP was not observed, presumably due to impeded substrate access to HMP orientated on Gr through the FAD-domain and/or partial denaturation of HMP. Bioelectrocatalysis was achieved when HMP was wired to Gr by the Os redox polymers, with the onset of NADH oxidation at the formal potential of the particular Os complex (+140 mV or -195 mV). Apparent Michaelis constants K(M)(app) and j(max) were determined, showing bioelectrocatalytic efficiency of NADH oxidation by HMP exceeding the one earlier shown with diaphorase, which makes HMP very attractive as a component of bioanalytical and bioenergetic devices.
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Abi A, Ferapontova EE. Unmediated by DNA Electron Transfer in Redox-Labeled DNA Duplexes End-Tethered to Gold Electrodes. J Am Chem Soc 2012; 134:14499-507. [DOI: 10.1021/ja304864w] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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62
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Jensen UB, Ferapontova EE, Sutherland DS. Quantifying protein adsorption and function at nanostructured materials: enzymatic activity of glucose oxidase at GLAD structured electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:11106-11114. [PMID: 22746098 DOI: 10.1021/la3017672] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nanostructured materials strongly modulate the behavior of adsorbed proteins; however, the characterization of such interactions is challenging. Here we present a novel method combining protein adsorption studies at nanostructured quartz crystal microbalance sensor surfaces (QCM-D) with optical (surface plasmon resonance SPR) and electrochemical methods (cyclic voltammetry CV) allowing quantification of both bound protein amount and activity. The redox enzyme glucose oxidase is studied as a model system to explore alterations in protein functional behavior caused by adsorption onto flat and nanostructured surfaces. This enzyme and such materials interactions are relevant for biosensor applications. Novel nanostructured gold electrode surfaces with controlled curvature were fabricated using colloidal lithography and glancing angle deposition (GLAD). The adsorption of enzyme to nanostructured interfaces was found to be significantly larger compared to flat interfaces even after normalization for the increased surface area, and no substantial desorption was observed within 24 h. A decreased enzymatic activity was observed over the same period of time, which indicates a slow conformational change of the adsorbed enzyme induced by the materials interface. Additionally, we make use of inherent localized surface plasmon resonances in these nanostructured materials to directly quantify the protein binding. We hereby demonstrate a QCM-D-based methodology to quantify protein binding at complex nanostructured materials. Our approach allows label free quantification of protein binding at nanostructured interfaces.
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Papadakis G, Tsortos A, Bender F, Ferapontova EE, Gizeli E. Direct Detection of DNA Conformation in Hybridization Processes. Anal Chem 2012; 84:1854-61. [DOI: 10.1021/ac202515p] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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64
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Jensen UB, Lörcher S, Vagin M, Chevallier J, Shipovskov S, Koroleva O, Besenbacher F, Ferapontova EE. A 1.76V hybrid Zn-O2 biofuel cell with a fungal laccase-carbon cloth biocathode. Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2011.12.026] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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65
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Farjami E, Clima L, Gothelf K, Ferapontova EE. "Off-on" electrochemical hairpin-DNA-based genosensor for cancer diagnostics. Anal Chem 2011; 83:1594-602. [PMID: 21314139 DOI: 10.1021/ac1032929] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A simple and robust "off-on" signaling genosensor platform with improved selectivity for single-nucleotide polymorphism (SNP) detection based on the electronic DNA hairpin molecular beacons has been developed. The DNA beacons were immobilized onto gold electrodes in their folded states through the alkanethiol linker at the 3'-end, while the 5'-end was labeled with a methylene blue (MB) redox probe. A typical "on-off" change of the electrochemical signal was observed upon hybridization of the 27-33 nucleotide (nt) long hairpin DNA to the target DNA, in agreement with all the hitherto published data. Truncation of the DNA hairpin beacons down to 20 nts provided improved genosensor selectivity for SNP and allowed switching of the electrochemical genosensor response from the on-off to the off-on mode. Switching was consistent with the variation in the mechanism of the electron transfer reaction between the electrode and the MB redox label, for the folded beacon being characteristic of the electrochemistry of adsorbed species, while for the "open" duplex structure being formally controlled by the diffusion of the redox label within the adsorbate layer. The relative current intensities of both processes were governed by the length of the formed DNA duplex, potential scan rate, and apparent diffusion coefficient of the redox species. The off-on genosensor design used for detection of a cancer biomarker TP53 gene sequence favored discrimination between the healthy and SNP-containing DNA sequences, which was particularly pronounced at short hybridization times.
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Pinijsuwan S, Shipovskov S, Surareungchai W, Ferapontova EE, Gothelf KV. Development of a lipase-based optical assay for detection of DNA. Org Biomol Chem 2011; 9:6352-6. [DOI: 10.1039/c0ob01165g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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68
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69
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Hansen MN, Farjami E, Kristiansen M, Clima L, Pedersen SU, Daasbjerg K, Ferapontova EE, Gothelf KV. Synthesis and application of a triazene-ferrocene modifier for immobilization and characterization of oligonucleotides at electrodes. J Org Chem 2010; 75:2474-81. [PMID: 20329775 DOI: 10.1021/jo9024368] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new DNA modifier containing triazene, ferrocene, and activated ester functionalities was synthesized and applied for electrochemical grafting and characterization of DNA at glassy carbon (GC) and gold electrodes. The modifier was synthesized from ferrocenecarboxylic acid by attaching a phenyltriazene derivative to one of the ferrocene Cp rings, while the other Cp ring containing the carboxylic acid was converted to an activated ester. The modifier was conjugated to an amine-modified DNA sequence. For immobilization of the conjugate at Au or GC electrodes, the triazene was activated by dimethyl sulfate for release of the diazonium salt. The salt was reductively converted to the aryl radical which was readily immobilized at the surface. DNA grafted onto electrodes exhibited remarkable hybridization properties, as detected through a reversible shift in the redox potential of the Fc redox label upon repeated hybridization/denaturation procedures with a complementary target DNA sequence. By using a methylene blue (MB) labeled target DNA sequence the hybridization could also be followed through the MB redox potential. Electrochemical studies demonstrated that grafting through the triazene modifier can successfully compete with existing protocols for DNA immobilization through the commonly used alkanethiol linkers and diazonium salts. Furthermore, the triazene modifier provides a practical one-step immobilization procedure.
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70
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Ferapontova EE, Hansen MN, Saunders AM, Shipovskov S, Sutherland DS, Gothelf KV. Electrochemical DNA sandwich assay with a lipase label for attomole detection of DNA. Chem Commun (Camb) 2010; 46:1836-8. [PMID: 20198225 DOI: 10.1039/b924627d] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A fast and sensitive electrochemical lipase-based sandwich hybridization assay for detection of attomole levels of DNA has been developed. A combination of magnetic beads, used for pre-concentration and bioseparation of the analyte with a lipase catalyst label allowed detection of DNA with a limit of 20 amol.
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Farjami E, Clima L, Gothelf KV, Ferapontova EE. DNA interactions with a Methylene Blue redox indicator depend on the DNA length and are sequence specific. Analyst 2010; 135:1443-8. [DOI: 10.1039/c0an00049c] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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72
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Kartashov AV, Serafini G, Dong M, Shipovskov S, Gazaryan I, Besenbacher F, Ferapontova EE. Long-range electron transfer in recombinant peroxidases anisotropically orientated on gold electrodes. Phys Chem Chem Phys 2010; 12:10098-107. [DOI: 10.1039/c0cp00605j] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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73
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Mamdouh W, Kelly REA, Dong M, Jacobsen MF, Ferapontova EE, Kantorovich LN, Gothelf KV, Besenbacher F. Self-Assembly of Artificial Nucleobase 1H-Benzimidazole-4,7-dione at the Liquid/Solid Interface. J Phys Chem B 2009; 113:8675-81. [DOI: 10.1021/jp9029419] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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74
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Ferapontova EE, Gothelf KV. Effect of serum on an RNA aptamer-based electrochemical sensor for theophylline. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:4279-4283. [PMID: 19301828 DOI: 10.1021/la804309j] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Electrochemical performance of the ferrocene (Fc) redox-labeled RNA aptamer based sensor for theophylline (Th) is essentially inhibited in serum, but is restored in serum-free buffer solutions. This phenomenon is inconsistent with the data on methylene-blue-labeled aptamer beacon systems, which operational potential window is more negative compared to the Fc redox label. Electrochemical studies with a ferricyanide redox probe, having redox potential close to the Fc redox couple, and interfacial capacitance measurements unambiguously demonstrate that it is adsorption of serum proteins at positively charged electrode surface that slows down the kinetics of the electrode reactions in serum and interferes with the biosensor performance. In filtered serum solutions, in the absence of serum proteins, the Fc-labeled aptamer-based biosensor performed similarly to the pure buffer solutions, ad the signal for Th could be linearly calibrated versus Th concentration. These results on interfacial effects of serum are of particular importance for future research and development of the beacon-type biosensors for in vivo applications.
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Jacobsen MF, Ferapontova EE, Gothelf KV. Synthesis and electrochemical studies of an anthraquinone-conjugated nucleoside and derived oligonucleotides. Org Biomol Chem 2009; 7:905-8. [PMID: 19225673 DOI: 10.1039/b816820b] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The synthesis of a 2'-deoxyuridine nucleoside linked to an anthraquinone moiety, and its incorporation into oligonucleotides are described, including a facile oxidative demethylation with phenyliodine(iii) bis(trifluoroacetate) to reveal the anthraquinone motif. Furthermore, some useful physical and electrochemical properties of the obtained oligonucleotide are also reported, which allow its principal use in electrochemical DNA assays.
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Ferapontova EE, Olsen EM, Gothelf KV. An RNA aptamer-based electrochemical biosensor for detection of theophylline in serum. J Am Chem Soc 2008; 130:4256-8. [PMID: 18324816 DOI: 10.1021/ja711326b] [Citation(s) in RCA: 263] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An electrochemical RNA aptamer-based biosensor for rapid and label-free detection of the bronchodilator theophylline was developed. The 5'-disulfide-functionalized end of the RNA aptamer sequence was immobilized on a gold electrode, and the 3'-amino-functionalized end was conjugated with a ferrocene (Fc) redox probe. Upon binding of theophylline the aptamer switches conformation from an open unfolded state to a closed hairpin-type conformation, resulting in the increased electron-transfer efficiency between Fc and the electrode. The electrochemical response, which was measured by differential pulse voltammetry, reaches saturation within a few minutes after addition of theophylline, and the dynamic range for detecting theophylline is 0.2-10 muM. The electrode displays an inhibited response when applied directly in serum samples treated with RNase inhibitors; however a full response to the theophylline serum concentration was obtained by transferring the electrode to blank serum-free buffer solutions. It was demonstrated that theophylline is detected with high selectivity in the presence of caffeine and theobromine.
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Andreu R, Ferapontova EE, Gorton L, Calvente JJ. Direct Electron Transfer Kinetics in Horseradish Peroxidase Electrocatalysis. J Phys Chem B 2006; 111:469-77. [PMID: 17214499 DOI: 10.1021/jp064277i] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The study of direct electron transfer between enzymes and electrodes is frequently hampered by the small fraction of adsorbed proteins that remains electrochemically active. Here, we outline a strategy to overcome this limitation, which is based on a hierarchical analysis of steady-state electrocatalytic currents and the adoption of the "binary activity" hypothesis. The procedure is illustrated by studying the electrocatalytic response of horseradish peroxidase (HRP) adsorbed on graphite electrodes as a function of substrate (hydrogen peroxide) concentration, electrode potential, and solution pH. Individual contributions of the rates of substrate/enzyme reaction and of the electrode/enzyme electron exchange to the observed catalytic currents were disentangled by taking advantage of their distinct dependence on substrate concentration and electrode potential. In the absence of nonturnover currents, adoption of the "binary activity" hypothesis provided values of the standard electron-transfer rate constant for reduction of HRP Compound II that are similar to those reported previously for reduction of cytochrome c peroxidase Compound II. The variation of the catalytic currents with applied potential was analyzed in terms of the non-adiabatic Marcus-DOS electron transfer theory. The availability of a broad potential window, where catalytic currents could be recorded, facilitates an accurate determination of both the reorganization energy and the maximum electron-transfer rate for HRP Compound II reduction. The variation of these two kinetic parameters with solution pH provides some indication of the nature and location of the acid/base groups that control the electronic exchange between enzyme and electrode.
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Ferapontova EE, Castillo J, Gorton L. Bioelectrocatalytic properties of lignin peroxidase from Phanerochaete chrysosporium in reactions with phenols, catechols and lignin-model compounds. Biochim Biophys Acta Gen Subj 2006; 1760:1343-54. [PMID: 16781814 DOI: 10.1016/j.bbagen.2006.04.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 02/09/2006] [Accepted: 04/05/2006] [Indexed: 10/24/2022]
Abstract
Bioelectrocatalytic reduction of H(2)O(2) catalysed by lignin peroxidase from Phanerochaete chrysosporium (LiP) was studied with LiP-modified graphite electrodes to elucidate the ability of LiP to electro-enzymatically oxidise phenols, catechols, as well as veratryl alcohol (VA) and some other high-redox-potential lignin model compounds (LMC). Flow-through amperometric experiments performed at +0.1 V vs. Ag|AgCl demonstrated that LiP displayed significant bioelectrocatalytic activity for the reduction of H(2)O(2) both directly (i.e., in direct electron transfer (ET) reaction between LiP and the electrode) and using most of studied compounds acting as redox mediators in the LiP bioelectrocatalytic cycle, with a pH optimum of 3.0. The bioelectrocatalytic reduction of H(2)O(2) mediated by VA and effects of VA on the efficiency of bioelectrocatalytic oxidation of other co-substrates acting as mediators were investigated. The bioelectrocatalytic oxidation of phenol- and catechol derivatives and 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulphonate) by LiP was independent of the presence of VA, whereas the efficiency of the LiP bioelectrocatalysis with the majority of other LMC acting as mediators increased upon addition of VA. Special cases were phenol and 4-methoxymandelic acid (4-MMA). Both phenol and 4-MMA suppressed the bioelectrocatalytic activity of LiP below the direct ET level, which was, however, restored and increased in the presence of VA mediating the ET between LiP and these two compounds. The obtained results suggest different mechanisms for the bioelectrocatalysis of LiP depending on the chemical nature of the mediators and are of a special interest both for fundamental science and for application of LiP in biotechnological processes as solid-phase bio(electro)catalyst for decomposition/detection of recalcitrant aromatic compounds.
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Ferapontova EE, Castillo J, Hushpulian D, Tishkov V, Chubar T, Gazaryan I, Gorton L. Direct electrochemistry of recombinant tobacco peroxidase on gold. Electrochem commun 2005. [DOI: 10.1016/j.elecom.2005.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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80
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Shipovskov S, Trofimova D, Saprykin E, Christenson A, Ruzgas T, Levashov AV, Ferapontova EE. Spraying Enzymes in Microemulsions of AOT in Nonpolar Organic Solvents for Fabrication of Enzyme Electrodes. Anal Chem 2005; 77:7074-9. [PMID: 16255612 DOI: 10.1021/ac050505d] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new technique suitable for automated, large-scale fabrication of enzyme electrodes by air-spraying enzymes in organic inks is presented. Model oxidoreductases, tyrosinase (Tyr) and glucose oxidase (GOx), were adapted to octane-based ink by entrapment in a system of reverse micelles (RM) of surfactant AOT in octane to separate and stabilize the catalytically active forms of the enzymes in nonpolar organic media. Nonpolar caoutchouk polymer was also used to create a kind of "dry micelles" at the electrode/solution interface. Enzyme/RM/polymer-containing organic inks were air-brushed onto conductive supports and were subsequently covered by sprayed Nafion membranes. The air-brushed enzyme electrodes exhibited relevant bioelectrocatalytic activity toward catechol and glucose, with a linear detection range of 0.1-100 microM catechol and 0.5-7 mM glucose; the sensitivities were 2.41 A M(-1) cm(-2) and 2.98 mA M(-1) cm(-2) for Tyr and GOx electrodes, respectively. The proposed technique of air-brushing enzymes in organic inks enables automated construction of disposable enzyme electrodes of various designs on a mass-production scale.
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E Ferapontova E, Gorton L. Direct electrochemistry of heme multicofactor-containing enzymes on alkanethiol-modified gold electrodes. Bioelectrochemistry 2005; 66:55-63. [PMID: 15833703 DOI: 10.1016/j.bioelechem.2004.04.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 03/31/2004] [Accepted: 04/13/2004] [Indexed: 11/28/2022]
Abstract
Direct electrochemistry of heme multicofactor-containing enzymes, e.g., microbial theophylline oxidase (ThOx) and D-fructose dehydrogenase (FDH) from Gluconobacter industrius was studied on alkanethiol-modified gold electrodes and was compared with that of some previously studied complex heme enzymes, specifically, cellobiose dehydrogenase (CDH) and sulphite oxidase (SOx). The formal redox potentials for enzymes in direct electronic communication varied for ThOx from -112 to -101 mV (vs. Ag|AgCl), at pH 7.0, and for FDH from -158 to -89 mV, at pH 5.0 and pH 4.0, respectively, on differently charged alkanethiol layers. Direct and mediated by cytochrome c electrochemistry of FDH correlated with the existence of two active centres in the protein structure, i.e., the heme and the pyrroloquinoline quinone (PQQ) prosthetic groups. The effect of the alkanethiols of different polarity and charge on the surface properties of the gold electrodes necessary for adsorption and orientation of ThOx, FDH, CDH and SOx, favourable for the efficient electrode-enzyme electron transfer reaction, is discussed.
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Ferapontova EE, Christenson A, Hellmark A, Ruzgas T. Spectroelectrochemical study of heme- and molybdopterin cofactor-containing chicken liver sulphite oxidase. Bioelectrochemistry 2004; 63:49-53. [PMID: 15110247 DOI: 10.1016/j.bioelechem.2003.09.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Revised: 09/10/2003] [Accepted: 09/16/2003] [Indexed: 11/30/2022]
Abstract
Electron transfer (ET) in sulphite oxidase (SOx), a heme- and molybdopterin cofactor-containing enzyme, was studied spectroelectrochemically using capillary gold electrode modified with aldrithiol. Direct electron exchange between SOx and the surface of modified gold was observed, with a formal potential of -115 mV vs. Agmid R:AgCl, KCl(sat) at pH 7.0. This value agreed well with that previously reported for redox transformation of the heme domain of SOx. However, no bioelectrocatalysis of sulphite oxidation was observed in phosphate buffer solutions. This fact evidently correlated with known inhibition of intramolecular ET in SOx by the presence of bivalent inorganic anions. After changing to a Tris buffer solution, spectra variations and cyclic voltammetry data designated direct ET-based bioelectrocatalysis of sulphite oxidation, upon addition of sulphite. Thus, the bioelectrocatalytic 2e(-) oxidation of sulphite catalysed by SOx due to direct ET exchange with the electrode was attained at aldrithiol-modified gold electrodes and shown to depend essentially on the nature of the buffer solution.
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Shipovskov S, Ferapontova EE, Gazaryan I, Ruzgas T. Recombinant horseradish peroxidase - and cytochrome c-based two-electrode system for detection of superoxide radicals. Bioelectrochemistry 2004; 63:277-80. [PMID: 15110287 DOI: 10.1016/j.bioelechem.2003.09.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Revised: 09/15/2003] [Accepted: 09/19/2003] [Indexed: 11/22/2022]
Abstract
The reliable detection of a superoxide anion radical O2(*-) is complicated by its spontaneous dismutation reaction to H2O2 at acidic pHs. To simultaneously detect both O2(*-) and H2O2 produced in the course of its spontaneous dismutation, an electrochemical two-electrode system based on cytochrome c (cyt c) and recombinant horseradish peroxidase (rHRP) was applied. Therewith, a limited applicability of the cyt c system for the reliable monitoring of O2(*-) in acidic and neutral solutions was shown. It was demonstrated that both the reaction of O2(*-) dismutation to H2O2 and the reaction between the formed H2O2 and O2(*-) chemically decrease the amount of the initially present O2(*-), decreasing the sensitivity and reliability of the electrochemical detection at acidic pH. However, by appropriately varying solution pH, the concentration of O2(*-) initially injected in the system can be estimated from the analysis of calibration curves for H2O2 obtained with highly sensitive rHRP-modified electrode system at pH 6.0 and 7.0.
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Ferapontova EE, Ruzgas T, Gorton L. Direct electron transfer of heme- and molybdopterin cofactor-containing chicken liver sulfite oxidase on alkanethiol-modified gold electrodes. Anal Chem 2004; 75:4841-50. [PMID: 14674462 DOI: 10.1021/ac0341923] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Direct heterogeneous electron transfer (ET) of sulfite oxidase (SOx), a heme- and molybdopterin cofactor-containing intermembrane enzyme, was studied on alkanethiol-modified Au electrodes both with SOx entrapped between the modified Au electrode and a permselective membrane and with SOx adsorbed at the electrode surface, in the absence of any membrane. SOx in direct electronic communication with the electrode surface gave a quasi-reversible electrochemical signal with a midpoint potential of--120 mV vs Ag/AgCl corresponding to the redox transformations of the heme domain of SOx and with a heterogeneous ET constant in the order of 15 s(-1). The efficiency of the bioelectrocatalytic 2e- oxidation of sulfite catalyzed by SOx in direct ET exchange with the electrode was shown to depend essentially on the nature of the alkanethiol layer. Adsorption and orientation of SOx on an 11-mercapto-1-undecanol (MuD-OH) self-assembled monolayer, i.e., terminally functionalized with OH groups, provided efficient catalytic oxidation of sulfite, contrary to nonfunctionalized alkanethiols, e.g., 1-decanethiol, or alkanethiol layers terminally functionalized with NH2 groups. Comparative studies with short-chain alkanethiols, e.g., cysteamine and 2-mercaptoethanol, revealed an evidently different mode of adsorption of SOx on these layers, onto which SOx was not catalytically active. Coadsorption of MuD-OH and 11-mercapto-1-undecanamine improved the surface properties of the SAM, resulting in a higher surface coverage with bioelectrocatalytically active SOx but not in an increased apparent catalytic rate constant, kcat, ranging in the order of 18-24 s(-1) at pH 7.4. The achieved efficiency of SOx bioelectrocatalysis in direct ET reaction between the modified electrode and the enzyme approached the rates characteristic for the catalysis mediated by cytochrome c, the natural redox partner of SOx, thus implying the retention of the biological function of SOx under the heterogeneous electrode reaction conditions. Results obtained enable the development of a third-generation biosensor for sulfite monitoring.
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Ferapontova EE, Shipovskov SV. Electrochemically induced oxidative damage to double-stranded calf thymus DNA adsorbed on gold electrodes. BIOCHEMISTRY. BIOKHIMIIA 2003; 68:99-104. [PMID: 12693982 DOI: 10.1023/a:1022153720508] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Electrochemically induced oxidative damage to DNA was studied with double-stranded calf thymus DNA immobilized directly on a gold electrode surface. Pre-polarization of the DNA-modified electrodes at +0.5 V versus Ag/AgCl reference electrode, in a free from DNA blank buffer solution, pH 7.4, allowed for subsequent detection of direct electrochemical oxidation of adsorbed on gold DNA, in the potential range from +0.7 to +0.8 V. The redox potential of the process corresponded to the potentials of the oxidation of guanine bases in DNA. It is shown that with increasing potential scan rate, v, the mechanism of electrochemical oxidation of DNA changes from the irreversible 4e(-) oxidative damage of DNA at low v to reversible 1e(-) oxidation at high v, keeping the electrochemical activity of the adsorbed DNA layer virtually the same.
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Ferapontova EE, Grigorenko VG, Egorov AM. P-chip and P-chip bienzyme electrodes based on recombinant forms of horseradish peroxidase immobilized on gold electrodes. BIOCHEMISTRY. BIOKHIMIIA 2001; 66:832-9. [PMID: 11566052 DOI: 10.1023/a:1011992316837] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Adsorption and bioelectrocatalytic activity of native horseradish peroxidase (HRP) and its recombinant forms on polycrystalline gold electrodes were studied. Recombinant forms of HRP were produced by a genetic engineering approach using an E. coli expression system. According to direct mass measurements with a quartz crystal microbalance, all the forms of HRP formed monolayer coverage of the enzyme on the gold surface. However, only gold electrodes modified with the recombinant HRP forms (non-glycosylated) exhibited high and stable current response to H2O2 due to its bioelectrocatalytic reduction based on direct electron transfer (ET) between gold and the active site of the enzyme. Introduction of a six-His tag either at the C-terminus or at the N-terminus of the enzyme molecule additionally increased the strength of the enzyme binding with the gold surface and the efficiency of direct ET. Immobilization of recombinant forms of HRP containing histidine functional groups on the surface of the gold electrode was used both for the development of a P-chip, a biosensor for hydrogen peroxide determination based on direct ET, and for the development of a bienzyme biosensor electrode for the determination of L-lysine based on co-immobilized recombinant forms of HRP and L-lysine-alpha-oxidase.
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Ferapontova EE, Grigorenko VG, Egorov AM, Börchers T, Ruzgas T, Gorton L. Direct electron transfer in the system gold electrode–recombinant horseradish peroxidases. J Electroanal Chem (Lausanne) 2001. [DOI: 10.1016/s0022-0728(01)00371-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ferapontova EE, Grigorenko VG, Egorov AM, Börchers T, Ruzgas T, Gorton L. Mediatorless biosensor for H(2)O(2) based on recombinant forms of horseradish peroxidase directly adsorbed on polycrystalline gold. Biosens Bioelectron 2001; 16:147-57. [PMID: 11339993 DOI: 10.1016/s0956-5663(01)00134-8] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Four forms of horseradish peroxidase (HRP) have been used to prepare peroxidase-modified gold electrodes for mediatorless detection of peroxide: native HRP, wild type recombinant HRP, and two recombinant forms containing six-His tag at the C-terminus and at the N-terminus, respectively. The adsorption of the enzyme molecules on gold was studied by direct mass measurements with electrochemical quartz crystal microbalance. All the forms of HRP formed a monolayer coverage of the enzyme on the gold surface. However, only gold electrodes with adsorbed recombinant HRP forms exhibited high and stable current response to H(2)O(2) due to its bioelectrocatalytic reduction based on direct electron transfer between gold and HRP. The sensitivity of the gold electrodes modified with recombinant HRPs was in the range of 1.4-1.5 A M(-1) cm(-2) at -50 mV versus Agmid R:AgCl. The response to H(2)O(2) in the concentration range 0.1-40 microM was not dependent on the presence of a mediator (i.e. catechol) giving strong evidence that the electrode currents are diffusion limited. Lower detection limit for H(2)O(2) detection was 10 nM at the electrodes modified with recombinant HRPs.
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