Electrochemical lactate biosensor based upon chitosan/carbon nanotubes modified screen-printed graphite electrodes for the determination of lactate in embryonic cell cultures, Biosensors and Bioelectronic, http://dx.doi.org/10.1016/j.bios.2015.11.005 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. This novel electrochemical lactate biosensors analytical efficacy is explored towards the sensing of lactate in model (buffer) solutions and is found to exhibit a linear response towards lactate over the concentration range of 30.4 and 243.9 µM in phosphate buffer solution, with a corresponding limit of detection (based on 3-sigma) of 22.6 µM and exhibits a sensitivity of 3417 ± 131 µA M -1 according to the reproducibility study. These novel electrochemical lactate biosensors exhibit a high reproducibility, with a relative standard deviation of less than 3.8 % and an enzymatic response over 82 % after 5 months stored at 4 ºC. Furthermore, high performance liquid chromatography technique has been utilized to independently validate the electrochemical lactate biosensor for the determination of lactate in a commercial embryonic cell culture medium providing excellent agreement between the two analytical protocols.
Please cite this article as: Ignacio Sanjuán, Ariadna Brotons, Naiara Hernández-Ibáñez, Christopher W.Foster, Craig E.Banks, Jesús Iniesta, Boron-doped diamond electrodes explored for the electroanalytical detection of 7-methylguanine and applied for its sensing within urine samples, Electrochimica Acta http://dx.doi.org/10.1016/j.electacta. 2015.11.026 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. SWV provides good resolution of the anodic peak for 7-mG and the main nucleic bases interferences, such as adenine and guanine. It is plausible the simultaneous determination of 7-mG and another of the most common modified nucleobases, 8-oxoguanine (8-oxoG). 7-mG electrochemical determination within a human urine sample is feasible with linear regression between peak current intensity versus 7-mG concentration. 3 AbstractEpigenetic modifications have been associated by many studies with several types of diseases and metabolic dysfunctions. Specifically, N7-methyl modification of guanine (7-mG) is well established to be used as a biomarker for the detection and determination of DNA methylation. The use of an electrochemical sensor has the potential to provide a simpler and more economic sensing methodology for the determination of 7-mG compared to traditionally utilised laboratory based approaches. In this paper we demonstrate the feasibility of an electrochemical sensor which could potentially be easily applied towards the determination of 7-mG within biological samples, such as human urine. A practical electrochemical configuration was employed consisting of a boron-doped diamond electrode (BDD) as the working electrode and a screen-printed graphite electrode (SPE) providing the counter electrode and the reference electrode.With this new protocol, the electrochemical behaviour of 7-mG has been investigated via cyclic voltammetry (CV) and square wave voltammetry (SWV) using a BDD electrode with a simplified electrochemical set-up The electrochemical behaviour of 7-mG within acetate buffer solutions at a BDD electrode has been compared and contrasted to a glassy carbon electrode with the following parameters studied: voltammetric scan rate, solution pH, 7-mG concentration and electrode surface pretreatment. The oxidative mechanism elucidation has been performed at controlled potential and such results have provided the dimer formation as the major product. The simultaneous electroanalytical identification of 7-mG together with the presence of guanine, adenine and 8-oxoguanine has been investigated under the optimum experimental conditions. Furthermore, the feasibility of using a BDD electrode for the ...
Thiol-containing compounds such as L-cysteine have been demonstrated to play an important role in metabolism and cellular growth, acting as powerful antioxidants.Consequently, their analytical determination in biological media has received a considerable amount of attention. In this work, an electrochemical sensor for the accurate electroanalytical determination of L-cysteine is proposed, based upon a Co(II)-phthalocyanine nanoparticle bulk modified disposable screen-printed graphite electrode (CoPc-SPE). This CoPc mediator has previously been introduced through its incorporation within the bulk of the ink formulation, avoiding the drop-casting method, which has been shown to give a low reproducibility. Cyclic (CV) and Square Wave
Hydrogen absorption is a crucial process in energy storage (microscopic or macroscopic) and management and here a porous organic cage (POC) material is shown to bind and release hydrogen when deposited directly onto a platinum electrode and immersed into aqueous electrolyte. Preliminary voltammetry experiments for the POC CC3 deposited onto a platinum disc electrode reveal uptake and release of hydrogen gas (probably coupled to water release and uptake, respectively) in the vicinity of the electrode. Significant pH effects on the rate of binding and release are reported and explained with a change in H2 binding rate. In future, "wet" POCs or POCs dispersed in aqueous solution could be employed for enhancing hydrogen capture/transport in energy applications. Graphical abstract:
The one-step vacuum carbonization synthesis of a platinum nano-catalyst embedded in a microporous heterocarbon (Pt@cPIM) is demonstrated. A nitrogen-rich polymer of an intrinsic microporosity (PIM) precursor is impregnated with PtCl62− to give (after vacuum carbonization at 700 °C) a nitrogen-containing heterocarbon with embedded Pt nanoparticles of typically 1–4 nm diameter (with some particles up to 20 nm diameter). The Brunauer-Emmett-Teller (BET) surface area of this hybrid material is 518 m2 g−1 (with a cumulative pore volume of 1.1 cm3 g−1) consistent with the surface area of the corresponding platinum-free heterocarbon. In electrochemical experiments, the heterocarbon-embedded nano-platinum is observed as reactive towards hydrogen oxidation, but essentially non-reactive towards bigger molecules during methanol oxidation or during oxygen reduction. Therefore, oxygen reduction under electrochemical conditions is suggested to occur mainly via a 2-electron pathway on the outer carbon shell to give H2O2. Kinetic selectivity is confirmed in exploratory catalysis experiments in the presence of H2 gas (which is oxidized on Pt) and O2 gas (which is reduced on the heterocarbon surface) to result in the direct formation of H2O2.
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