Amperometric Biosensor for Choline Based on Gold Screen‐Printed Electrode Modified with Electrochemically‐Deposited Silica Biocomposite

A mediator‐free choline biosensor was developed using the electrochemically assisted sol‐gel deposition on gold screen‐printed electrodes. The addition of 12 mM of cationic surfactant CTAB in silica sol allowed enhancing the stability of the sensor. The modified electrode demonstrated catalytic activity and stable amperometric response to choline for over 3 weeks of exploitation with the sensitivity of 6 µA mM^?1 and LOD of 6 µM. The interference of ascorbic acid was reduced by pretreating the analyzed solution with MnO₂ powder. The application of the sensor with the purpose of identifying choline in the baby milk demonstrated satisfactory metrological characteristics.     

Choline hydroxide promoted sustainable one-pot three-component synthesis of 1H-pyrazolo[1,2-a]pyridazine-2-carbonitriles under solvent-free conditions

Abstract

A sustainable one-pot three-component synthesis of novel 1H-pyrazolo[1,2-a]pyridazine-2-carbonitrile derivatives employing a highly efficient, biodegradable, and recyclable choline hydroxide catalyst under solvent-free conditions is demonstrated. The salient features of this protocol are simple workup, mild reaction conditions, short reaction time (10?min), excellent yields (up to 97%), high atom economy, column chromatography-free protocol, and eco-friendliness. Interestingly, the choline hydroxide was recycled up to five cycles without any considerable loss of efficiency. The structures of the products were deduced by their ¹H NMR, ¹³C NMR, and HRLC-MS spectra.     

Tandem isomerization-lactonization of olefinic fatty acids using the Lewis acidic ionic liquid, choline chloride·2ZnCl2

The tandem isomerization-lactonization of unsaturated fatty acids to their corresponding γ-lactones was carried out for the first time in the presence of a Lewis acidic ionic liquid, choline chloride·2ZnCl₂. The ionic liquid initially catalyzes the stepwise migration of the double bond along the carbon chain toward the carboxyl group at the Δ4 position, which subsequently undergoes lactonization resulting in the formation of γ-lactones. This one step process allows the formation of γ-lactone in good yield with little or no formation of δ-lactones. The studied ionic liquid plays the dual role of solvent as well as catalyst.     

毛细管电泳电导法快速检测饲料添加剂氯化胆碱

采用毛细管电泳电导法对饲料添加剂氯化胆碱进行了测定.实验优化了缓冲介质、分离电压、毛细管长度和内径等参数.结果表明:在优化条件下,氯化胆碱在4 min左右可以实现分离检测,线性范围在41.8～1.20 μg/mL,检出限为0.8 μg/mL;迁移时间和峰面积的相对标准偏差分别为0.6%、2.1%;样品加标回收率为97%～105%.将该法用于粉剂和饲料中氯化胆碱的检测,取得了满意的结果.     

Amperometric determination of choline with enzyme immobilized in a hybrid mesoporous membrane

Choline sensor is successfully prepared by using immobilized enzyme, i.e., choline oxidase (ChOx) within a hybrid mesoporous membrane with 12 nm pore diameter (F127M). The measurement was based on the detection of hydrogen peroxide, which is the co-product of the enzymatic choline oxidation. The determination range and the response time are 5.0-800 μM and approximately 2 min, respectively. The sensor is very stable compared to the native enzyme sensor and 85% of the initial response was maintained even after storage for 80 days. These results indicate that ChOx is successfully immobilized and well stabilized, and at the same time, enzyme reaction proceeds efficiently. Such ability of hybrid mesoporous membrane F127M suggests great promise for effective immobilization of enzyme useful for electrochemical biosensors.     

A Highly Sensitive Electrochemiluminescence Choline Biosensor Based on Poly(aniline‐luminol‐hemin) Nanocomposites

Poly(aniline‐luminol‐hemin) nanocomposites are prepared on an electrode surface through electropolymerization, and a highly sensitive electrochemiluminescence (ECL) biosensor for choline is developed based on the poly(aniline‐luminol‐hemin) nanocomposites and an enzyme catalyzed reaction of choline oxidase (CHOD). The obtained nanocomposites are characterized by scanning electron microscopy (SEM), atomic absorption spectrometry (AAS) and ECL. The results indicate that hemin can be incorporated into the poly(aniline‐luminol) nanocomposites using the facile electropolymerization method, and the poly(aniline‐luminol‐hemin) nanocomposites are rod shaped porous nanostructure. Moreover, the poly(aniline‐luminol‐hemin) nanocomposites exhibit higher ECL intensity than poly(aniline‐luminol) nanocomposites in alkaline media due to the catalytic effect of hemin on the ECL of the polymerized luminol and the electron transfer ability of hemin in the nanocomposites. CHOD is immobilized on the surface of the poly(aniline‐luminol‐hemin) nanocomposites modified electrode with glutaraldehyde, and the ECL biosensor based on poly(aniline‐luminol‐hemin)/CHOD exhibits a wider linear range for the choline detection. The enhanced ECL signals are linear with the logarithm of concentration of choline over the range of 1.0×10^?11～1.0×10^?7 mol L^?1 with a low detection limit of 1.2×10^?12 mol L^?1. Moreover, the proposed biosensor is successfully applied to the detection of choline in milk.     

胆碱酯酶场效应管传感器

将乙酰胆碱酯酶和牛血清白蛋白通过戊二醛共交联，固定在氢离子敏场效应管的栅极上，制成胆碱酯酶场应效管传感器。采用差动检测方式，用两只传感器可测出１０＾－７ｍｏｌ／Ｌ的敌敌畏等有机磷农药。线性范围为５×１０＾－７－８×１０＾－６ｍｏｌ／Ｌ，具有强的抗干能力，寿命为２０ｄ以上。     

Determining pirimiphos-methyl in durum wheat samples using an acetylcholinesterase inhibition assay

An electrochemical assay used for detecting acetylcholinesterase (AChE) inhibitors has been optimised to detect pirimiphos-methyl in durum wheat. Pirimiphos-methyl is a phosphothionate insecticide and so it needs to be transformed into the corresponding oxo form to act as an effective AChE inhibitor. The inhibition assay was based on the electrochemical detection of the product of AChE, choline, via choline oxidase biosensors obtained with Prussian-Blue modified screen printed electrodes. The procedure for the oxidation of pirimiphos methyl via N-bromosuccinimide (NBS) and AChE inhibition was optimised for reagent concentrations and inhibition time in a buffer solution. A calibration of the pirimiphos-methyl (25–1,000 ng/ml) was obtained in the buffer. The intra-electrode CV ranged between 1.6 and 15.0, whereas the inter-electrode CV ranged between 4.6 and 16.0. The detection limit (LOD) was 38 ng/ml, and the I_50% was 360 ng/ml. The assay conditions were then re-optimised to work with durum wheat extracts, and the calibrations were obtained under different experimental conditions, such as sample pretreatment (milled or whole grains) and extract concentration. The calibrations were slightly affected by the sample matrix, resulting in an increased LOD (65–133 ng/ml) and I_50% (640–1,650 ng/ml). The LOD found for the sample, determined under optimal conditions, was 3 mg/kg. Spiked samples were prepared at the EU regulated level (5 mg/kg) and analysed with the optimised protocol, resulting in an average recovery of 70.3%.     

Development of deep eutectic solvents applied in extraction and separation

Deep eutectic solvents, as an alternative to ionic liquids, have greener credentials than ionic liquids, and have attracted considerable attention in related chemical research. Deep eutectic solvents have attracted increasing attention in chemistry for the extraction and separation of various target compounds from natural products. This review highlights the preparation of deep eutectic solvents, unique properties of deep eutectic solvents, and synthesis of deep‐eutectic‐solvent‐based materials. On the other hand, application in the extraction and separation of deep eutectic solvents is also included in this report. In this paper, the available data and references in this field are reviewed to summarize the applications and developments of deep eutectic solvents. Based on the development of deep eutectic solvents, an exploitation of new deep eutectic solvents and deep eutectic solvents‐based materials is expected to diversify into extraction and separation.     

1D Choline-PbI3-Based Heterostructure Boosts Efficiency and Stability of CsPbI3 Perovskite Solar Cells

Defects in perovskite are key factors in limiting the photovoltaic performance and stability of perovskite solar cells (PSCs). Generally, choline halide (ChX) can effectively passivate defects by binding with charged point defects of perovskite. However, we verified that ChI can react with CsPbI₃ to form a novel crystal phase of one-dimensional (1D) ChPbI₃, which constructs 1D/3D heterostructure with 3D CsPbI₃, passivating the defects of CsPbI₃ more effectively and then resulting in significantly improved photoluminescence lifetime from 20.2 ns to 49.4 ns. Moreover, the outstanding chemical inertness of 1D ChPbI₃ and the repair of undesired δ-CsPbI₃ deficiency during its formation process can significantly enhance the stability of CsPbI₃ film. Benefiting from 1D/3D heterostructure, CsPbI₃ carbon-based PSCs (C-PSCs) delivered a champion efficiency of 18.05 % and a new certified record of 17.8 % in hole transport material (HTM)-free inorganic C-PSCs.