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Aim. Development of an amperometric biosensor for measuring choline concentration in water samples. Methods. A bioselective element of the biosensor was created using choline oxidase which was covalently immobilized by glutaraldehyde crosslinking with bovine serum albumin on the surface of an amperometric platinum disk electrode. Results. The condi...
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... bare transducer reacted to certain substances quite strongly, which could be a problem while analyzing the real samples. The deposition of PPD membrane resulted in essential decrease or even complete absence of the biosensor responses to interferents whereas the sensitivity to hydrogen peroxide remained almost the same (Table 1). It was also found that the reproducibility of the biosensor signals to choline is significantly improved with the PPD membrane deposition due to better adhesion of biomembrane to the electrode. ...Similar publications
A simple, selective and stable biosensor with the enzymatic reactor based on choline oxidase (ChOx) was developed and applied for the determination of choline (Ch) in flow injection analysis with amperometric detection. The enzyme ChOx was covalently immobilized with glutaraldehyde to mesoporous silica powder (SBA‐15) previously covered by NH2‐grou...
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... Despite the high sensitivity of conventional chromatography methods, these methods are time-consuming, expensive, and complex, requiring skilled expertise. Therefore, new bioanalytical devices based on biosensors have replaced these methods [8,9]. Many biosensors have been designed, such as amperometric enzyme sensors, amperometric aqueous sol-gel biosensors, optical sensors based on fluorescent polymers and chemiluminescent flow sensors. ...
The electrocatalytical activity of nortropine-N-oxyl (NNO) was evaluated by cyclic voltammetry in pH 7.4 phosphate buffer solution. The anodic peak current for choline was enhanced in a concentration-dependent fashion, showing that choline was oxidized by the electrocatalytic effect of NNO. A high linear response to the choline concentration ranging from 0.1 to 10 mM was obtained. In contrast, 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) could not oxidize choline under the same conditions. Keywords: Choline, Electrocatalytic oxidation, Nitroxyl radical, Non-enzymatic system
Cholinergic signaling, i.e., neurotransmission mediated by acetylcholine, is involved in a host of physiological processes, including learning and memory. Cholinergic dysfunction is commonly associated with neurodegenerative diseases, including Alzheimer's disease. In the gut, acetylcholine acts as an excitatory neuromuscular signaler to mediate smooth muscle contraction, which facilitates peristaltic propulsion. Gastrointestinal dysfunction has also been associated with Alzheimer's disease. This research focuses on the preparation of an electrochemical enzyme-based biosensor to monitor cholinergic signaling in the gut and its application for measuring electrically stimulated acetylcholine release in the mouse colon ex vivo. The biosensors were prepared by platinizing Pt microelectrodes through potential cycling in a potassium hexachloroplatinate (IV) solution to roughen the electrode surface and improve adhesion of the multienzyme film. These electrodes were then modified with a permselective poly(m-phenylenediamine) polymer film, which blocks electroactive interferents from reaching the underlying substrate while remaining permeable to small molecules like H2O2. A multienzyme film containing choline oxidase and acetylcholinesterase was then drop-cast on these modified electrodes. The sensor responds to acetylcholine and choline through the enzymatic production of H2O2, which is electrochemically oxidized to produce an increase in current with increasing acetylcholine or choline concentration. Important figures of merit include a sensitivity of 190 ± 10 mA mol-1 L cm-2, a limit of detection of 0.8 μmol L-1, and a batch reproducibility of 6.1% relative standard deviation at room temperature. These sensors were used to detect electrically stimulated acetylcholine release from mouse myenteric ganglia in the presence and absence of tetrodotoxin and neostigmine, an acetylcholinesterase inhibitor.
This work demonstrated a novel, facile and efficient biosensor for dual-emitting ratiometric and visual fluorescence detection of choline. Copper nanoclusters (CuNCs) were prepared by using N2H4·H2O as the reducing agent and lysozyme as the stabilizer, based on an ambient hydrothermal method. The prepared CuNCs were blue-emitting and had an emission center peaked at 440 nm. In the mixture system consisting of CuNCs, choline oxidase, horseradish peroxidase (HRP) and o-phenylenediamine (OPD), the added choline was catalyzed by choline oxidase to generate H2O2. OPD was oxidized by H2O2 and HRP to generate 2,3-diaminophenazine (DAP). As the oxidation product of OPD, DAP emitted a fluorescence peaked at 550 nm and the fluorescence exhibited a regular enhancement with the increase of choline concentration. Meanwhile, CuNCs’ fluorescence was reduced by DAP due to an internal filtration effect-induced fluorescence quenching. There is an optimal linear relationship (r = 0.9992) between ratiometric fluorescence intensity (IDAP/ICuNCs, I550/I440) and choline concentration in the range of 0.1−80 μM, with a low limit of detection of 25 nM. The response of IDAP/ICuNCs to choline was sensitive and selective, over potential interferents existing in real samples. This developed sensor enabled the naked-eye visual detection of choline in aqueous solutions and on immersed filter papers. In human serum and liquid milk samples, this sensor had a superior performance for choline detection.
Changes in choline levels can be associated with diseases such as Alzheimer, Parkinson, Huntington, fatty liver, interstitial lung abnormalities, autism and so on. Therefore, quantitative determination of choline is important in biological and clinical analysis. So far, several methods have been investigated for measuring choline in the body fluids, each of which has disadvantages such as the need for specialist ability, complexity, and high cost. For this purpose, a facile and sensitive colorimetric biosensor based on DNAzyme-choline oxidase coupling used for the determination of choline. In this method, the first, choline oxidase produces H2O2 and betaine in the presence of choline and oxygen, then, the DNAzyme converts colorless ABTS into green ABTS+ radicals. Compared to the previous methods, the linear range and the limit of detection of this talented biosensor were 0.1-25 μM and 22 nM. Choline measurement using this biosensor has shown satisfactory selectivity and repeatability. Its recovery was 96.95-107.73%, which shows the reliability of biosensor assay in biological samples. Simplicity, low cost, naked eye, high sensitivity, and precision are the benefits of this colorimetric method. Taken to gather, the proposed system can be considered as a great biosensor for measuring choline levels especially in point of care diagnostic.
В роботі проведено оптимізацію роботи амперометричного біосенсора для визначення концентрацій холіну в біологічних рідинах. Для створення біоселективного елементу використовували холін оксидазу, іммобілізовану на поверхні амперометричного перетворювача. Досліджено вплив параметрів робочого буферного розчину (буферна ємність, іонна сила, рН) на характеристики біосенсора. Показано залежність активності іммобілізованого ферменту від рН розчину та визначено pH оптимум роботи біосенсора. Біосенсор характеризується гарною відтворюваністю сигналу та операційною стабільністю. В роботі перевірено можливість зберігання біосенсора за різних умов. Найкращі результати спостерігалися при зберіганні за температури -18 °С. Завдяки використанню мембрани з полі-m-фенілендіаміну було значно зменшено вплив інтерферуючих речовин на роботу біосенсора. Досліджено основні аналітичні характеристики біосенсора: чутливість, лінійний діапазон роботи, мінімальну межу визначення, шум, дрейф, відтворюваність відгуків біосенсора. Розроблений біосенсор можна використовувати для визначення концентрацій холіну в біологічних зразках.
