| 1. |
- Debela, Ahmed M., et al.
(author)
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Facile Electrochemical Hydrogenation and Chlorination of Glassy Carbon to Produce Highly Reactive and Uniform Surfaces for Stable Anchoring of Thiolated Molecules
- 2014
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In: Chemistry - A European Journal. - : Wiley-VCH Verlagsgesellschaft. - 0947-6539 .- 1521-3765. ; 20:25, s. 7646-7654
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Journal article (peer-reviewed)abstract
- Carbon is a highly adaptable family of materials and is one of the most chemically stable materials known, providing a remarkable platform for the development of tunable molecular interfaces. Herein, we report a two-step process for the electrochemical hydrogenation of glassy carbon followed by either chemical or electrochemical chlorination to provide a highly reactive surface for further functionalization. The carbon surface at each stage of the process is characterized by AFM, SEM, Raman, attenuated total reflectance (ATR) FTIR, X-ray photoelectron spectroscopy (XPS), and electroanalytical techniques. Electrochemical chlorination of hydrogen-terminated surfaces is achieved in just 5 min at room temperature with hydrochloric acid, and chemical chlorination is performed with phosphorus pentachloride at 50 °C over a three-hour period. A more controlled and uniform surface is obtained using the electrochemical approach, as chemical chlorination is observed to damage the glassy carbon surface. A ferrocene-labeled alkylthiol is used as a model system to demonstrate the genericity and potential application of the highly reactive chlorinated surface formed, and the methodology is optimized. This process is then applied to thiolated DNA, and the functionality of the immobilized DNA probe is demonstrated. XPS reveals the covalent bond formed to be a CS bond. The thermal stability of the thiolated molecules anchored on the glassy carbon is evaluated, and is found to be far superior to that on gold surfaces. This is the first report on the electrochemical hydrogenation and electrochemical chlorination of a glassy carbon surface, and this facile process can be applied to the highly stable functionalization of carbon surfaces with a plethora of diverse molecules, finding widespread applications.
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| 2. |
- Debela, A. M., et al.
(author)
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Functionalized deoxynucleotides and DNA primers for electrochemical diagnostics of disease predispostions
- 2017
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In: ECS Transactions. - : Electrochemical Society Inc.. - 1938-6737 .- 1938-5862. - 9781607685395 ; , s. 1873-1883, s. 1873-1883
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Conference paper (peer-reviewed)abstract
- Redox labeled DNAs are of increasing interest for the fabrication of next generation molecular tools. In the present work we are investigating the use of various redox labeled dNTPs, ddNTPs and DNA primers for use in detection of diseases. We have reported the use of Polyoxometalate (POM) labeled DNA primers and dNTPs for use in PCR and subsequently used for direct electrochemical detection of PCR products. The use of POM labeled DNAs in PCR enabled us to check the compatibility with polymerases and PCR incorporability of the modified DNAs. Furthermore we have investigated the solid-phase array based primer extension (é-PEX) with redox labelled ddNTPs (ferrocene (Fc), anthraquinone (AQ) phenothiazine (PTZ) and methylene blue (MB)) to prove the strategy of detection of single nucleotide polymorphisms using the labeled ddNTPs. This strategy will allow the development of cost-effective, rapid and user-friendly platform for the screening of known and unknown genetic mutations.
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| 3. |
- Mehdi Debela, Ahmed, et al.
(author)
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Surface functionalisation of carbon for low cost fabrication of highly stable electrochemical DNA sensors
- 2015
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In: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 71, s. 25-29
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Journal article (peer-reviewed)abstract
- An alternative strategy for surface tethering of DNA probes, where highly reactive glassy carbon (GC) substrates are prepared via electrochemical hydrogenation and electrochemical/chemical chlorination is reported. Thiolated DNA probes and alkanethiols were stably immobilised on the halogenated carbon, with electrochemical chlorination being milder, thus producing less damage to the surface. Electrochemical DNA sensors prepared using this surface chemistry on carbon with electrochemical chlorination providing an improved performance,producing a highly ordered surface and the use of lateral spacers to improve steric accessibility to immobilised probes was not required.
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| 4. |
- Torrens, Mabel, et al.
(author)
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Amperometric detection of Francisella tularensis genomic sequence on Zn-mediated diazonium modified substrates
- 2015
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In: Electrochemistry communications. - : Elsevier. - 1388-2481 .- 1873-1902. ; 53
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Journal article (peer-reviewed)abstract
- A simple, rapid and potentiostat-free method for grafting of close to monolayers of diazonium salts to anchor DNA probes for application in highly sensitive electrochemical genosensing is presented. Zn-mediated grafting is demonstrated to produce a highly organised surface facilitating enhanced sensitivity and a notably reduced detection limit as compared to electrochemical grafting. (C) 2015 Elsevier B.V. All rights reserved.
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| 5. |
- Torrens, Mabel, et al.
(author)
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Controlled Zn-Mediated Grafting of Thin Layers of Bipodal Diazonium Salt on Gold and Carbon Substrates
- 2015
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In: Chemistry - A European Journal. - : Wiley-VCH Verlagsgesellschaft. - 0947-6539 .- 1521-3765. ; 21:2, s. 671-681
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Journal article (peer-reviewed)abstract
- A controlled, rapid, and potentiostat-free method has been developed for grafting the diazonium salt (3,5-bis(4-diazophenoxy)benzoic acid tetrafluoroborate (DCOOH)) on gold and carbon substrates, based on a Zn-mediated chemical dediazonation. The highly stable thin layer organic platforms obtained were characterized by cyclic voltammetry, AFM, impedance, XP, and Raman spectroscopies. A dediazonation mechanism based on radical formation is proposed. Finally, DCOOH was proved as a linker to an aminated electroactive probe.
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