Screen‐printed Electrode Modified with ZnFe 2 O 4 Nanoparticles for Detection of Acetylcholine

FAST (Flexible Acetylcholine Sensing Thread): Real-Time Detection of Acetylcholine with a Flexible Solid-Contact Potentiometric Sensor

Acetylcholine (ACh) is involved in memory and learning and has implications in neurodegenerative diseases; it is therefore important to study the dynamics of ACh in the brain. This work creates a flexible solid-contact potentiometric sensor for in vitro and in vivo recording of ACh in the brain and tissue homogenate. We fabricate this sensor using a 250 μm diameter cotton yarn coated with a flexible conductive ink and an ACh sensing membrane that contains a calix[4]arene ionophore. The exposed ion-to-electron transducer was sealed with a 2.5 μm thick Parylene C coating to maintain the flexibility of the sensor. The resulting diameter of the flexible ACh sensing thread (FAST) was 400 μm. The FAST showed a linear response range from 1.0 μM to 10.0 mM in deionized water, with a near-Nernstian slope of 56.11 mV/decade and a limit of detection of 2.6 μM. In artificial cerebrospinal fluid, the limit of detection increased to 20 μM due to the background signal of ionic content of the cerebrospinal fluid. The FAST showed a signal stability of 226 μV/h over 24 h. We show that FAST can measure ACh dynamics in sheep brain tissue and sheep brain homogenate after ACh spiking. FAST is the first flexible electrochemical sensor for monitoring ACh dynamics in the brain.

Advancing interfacial properties of carbon cloth via anodic-induced self-assembly of MOFs film integrated with α-MnO2: A sustainable electrocatalyst sensing acetylcholine

The metal organic frameworks (MOFs) with tunable composition, modified structure, and morphologically controlled nanoarchitectures are quite imperative to improve the electrochemical (EC) performances of sensing platforms. Herein, EC control over the fabrication of HKUST-1 (Cu-MOFs) nanocrystals is achieved via anodic-induced electrodeposition approach following the mixing of Cu²⁺ salt precursor in the vicinity of benzene-1,3,5-tricarboxylate (BTC^3-) ligands. The problem of controlled mass transfer and slow dispersal of MOFs is resolved by EC deposition of pyramidal-octagonal MOFs on a highly conductive and flexible carbon substrate (activated carbon cloth, ACC) wrapped with rGO layers (ACC-rGO@Cu(BTC). Further, α-MnO₂ is integrated on ACC-rGO@Cu(BTC) to achieve the synergistic effect of ternary structure interfaces. The novel ACC-rGO@Cu(BTC)@MnO₂ based flexible electrode exhibits striking EC performance toward non-enzymatic sensing of acetylcholine (ACh) including wide linear range (0.1 µM - 3 mM), lowest detection limit (5 nM, S/N = 3), high selectivity, and long-term stability. Moreover, the developed sensing system has been applied for real-time detection of ACh efflux released from three different cell lines and biological matrices. Our work unlocks a new prospect of precisely structured MOFs with extensive functionalities and scaled-up fabrication methods via selection of nanoscale reaction centers to develop flexible sensing devices.

An overview of recent analysis and detection of acetylcholine

Acetylcholine (ACh), the major neurotransmitter secreted by cholinergic neurons, is widely found in the peripheral and central nervous systems, and its main function is to complete the transmission of neural signals. When cholinergic neurons are impaired, the synthesis and decomposition of ACh are abnormal and the neural signalling transition is blocked. To some extent, the concentration changes of ACh reflects the occurrence and development of many kinds of nervous system diseases, such as Alzheimer's disease, Parkinson's disease, Myasthenia gravis and so on. Thus, researches of the physiological and pathological roles and the tracking of the concentration changes of ACh in vivo are significant to the prevention and treatment of these diseases. In the paper, the pathophysiological functions and the comprehensive research progress on detection methods of ACh are summarized. Specifically, the latest research and related applications of the optical and electrochemical biosensors are described, and the future development directions and challenges are prospected, which provides a reference for the detection and applications of ACh.

Dual-Ionomer-Based Device: Acetylcholine Transport and Nonenzymatic Sensing

The malfunctioning in the release of acetylcholine (ACh⁺), leading to consequential damages in the neural system, has become an impulsion for the development of numerous progressive transport and detection gadgets. However, several challenges, such as laterality and complexity of transport devices, low precision of amperometric detection systems, and sumptuous, multistaged enzymatic quantification methods, have not yet been overcome. Herein, ionomers, because of their selective ion transporting nature, are chosen as suitable candidates for being implemented into both targeted ACh⁺ delivery and sensing systems. Based on these two approaches, for the very first time in the literature, the disulfonated poly(arylene ether sulfone) membrane is concurrently (i) used in the mimicry of transduction of the electrical-to-ionic signal in a neural network as "Acetylcholine Pen" (ACh⁺ Pen) and (ii) operated as a highly sensitive, conductivity-based ACh⁺ quantifier. Our dual device, being able to operate under an actual action potential of 55 mV_bias, shows a strong potential of future applicability in real-time ionic delivery-and-sensing systems.

Fabrication of magnetic iron oxide-supported copper oxide nanoparticles (Fe3O4/CuO): modified screen-printed electrode for electrochemical studies and detection of desipramine

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe₃O₄/CuO nanoparticles (NPs). Fe₃O₄/CuO NPs were synthesized via a coprecipitation procedure, and the products were characterized via energy disperse spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and vibrating sample magnetometer. The voltage–current curve and differential pulse voltammetry examinations of Fe₃O₄/CuO-modified screen-printed electrode (Fe₃O₄/CuO/SPE) were followed by the determination of electro-catalytic activities toward desipramine oxidation in a phosphate buffer solution (pH = 7.0). In addition, the value of diffusion coefficient (D = 3.0 × 10⁻⁶ cm² s⁻¹) for desipramine was calculated. Then, based on the optimum conditions, it was observed that the currents of the oxidation peak were linearly proportionate to the concentration of desipramine in the broad range between 0.08 and 400.0 μM and LOD of 0.03 μM (S/N = 3). Finally, our new sensor was successfully utilized to detect desipramine in the real samples, with reasonable recovery in the range of 97.2% to 102.7%.

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe₃O₄/CuO nanoparticles.