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This research introduces a non-enzymatic electrochemical sensor utilizing flower-like nickel oxide/carbon (fl-NiO/C) microspheres for the precise detection of L-glutamic acid (LGA), a crucial neurotransmitter in the field of healthcare and a frequently utilized food additive and flavor enhancer. The fl-NiO/C were synthesized with controllable microstructures using metal–organic frameworks (MOFs) as precursors followed by a simple calcination process. The uniformly synthesized fl-NiO/C microspheres were further characterized using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and field emission scanning electron microscopy (FE-SEM). The fl-NiO/C was utilized as a modifier on the surface of a glassy carbon electrode, and an impedimetric sensor based on electrochemical impedance spectroscopy (EIS) was developed for the detection of LGA. The proposed sensor demonstrated excellent catalytic activity and selectivity towards LGA across a broad concentration range of 10–800 μM with a sensitivity of 486.9 µA.mM−1.cm−2 and a detection limit of 1.28 µM (S/N = 3). The sensor was also employed to identify LGA in blood plasma samples, yielding results that align with those obtained through HPLC. This achievement highlights the potential of fl-NiO/C microspheres in advancing cutting-edge biosensing applications. [ABSTRACT FROM AUTHOR]

An advanced process for the manufacturing of aerogel-lined capillaries is presented; these are applicable as liquid-core waveguides for gaining the Raman signal of aqueous samples. With respect to the spin-coating process we have used so far for the manufacturing of aerogel-lined capillaries, the here-presented manufacturing process is advanced as it enables (i) the lining of longer capillaries, (ii) the adjustment of the lining-thickness via the lining velocity, and (iii) the reproducible generation of crack-free linings. The key parameters of the advanced process and their effect on the fabrication of aerogel-lined capillaries with optimal Raman signal gain are reported and related to the thickness and topography of the aerogel linings by the support of scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Mercury ion (Hg2+) is one of the most toxic pollutants that can exist throughout the environment and be diffused into water, soil, air, and eventually the food chain. Even a very low level of Hg2+ diffused in living organisms can hurt their DNA and cause the permanent damage of the central nervous system and a variety of consequential disorders. Hence, the development of a sensitive and specific method for the detection of Hg2+ at trace ranges is extremely important as well as challenging. Fluorometric detection assays based on graphene quantum dots (GQDs) and carbon quantum dots (CQDs) offer considerable potential for the determination and monitoring of heavy metals due to their fascinating properties. Although the quantum yield of GQDs and CQDs is sufficient for their use as fluorescent probes, doping with heteroatoms can significantly improve their optical properties and selectivity toward specific analytes. This review explores the primary advances of CQDs and GQDs in their great electronic, optical, and physical properties, their synthetic methods, and their use in Hg2+ fluorimetry detection. [ABSTRACT FROM AUTHOR]

This study aims to establish and optimize a process for the fabrication of 3D microstructures of the biocompatible polymer Parylene C using hot embossing techniques. The different process parameters such as embossing temperature, embossing force, demolding temperature and speed, and the usage of a release agent were optimized, utilizing adhesive micropillars as a use case. To enhance compatibility with conventional semiconductor fabrication techniques, hot embossing of Parylene C was adapted from conventional stainless steel substrates to silicon chip platforms. Furthermore, this adaptation included an investigation of the effects of the hot embossing process on metal layers embedded in the Parylene C, ensuring compatibility with the ultra-thin Parylene printed circuit board (PCB) demonstrated previously. To evaluate the produced microstructures, a combination of characterization methods was employed, including light microscopy (LM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). These methods provided comprehensive insights into the morphological, chemical, and structural properties of the embossed Parylene C. Considering the improved results compared to existing patterning techniques for Parylene C like plasma etching or laser ablation, the developed hot embossing approach yields a superior structural integrity, characterized by increased feature resolution and enhanced sidewall smoothness. These advancements render the method particularly suitable for diverse applications, including but not limited to, sensor optical components, adhesive interfaces for medical wearables, and microfluidic systems. [ABSTRACT FROM AUTHOR]

In this study, a facile approach for simultaneous determination of dopamine (DA) and tryptophan (TRP) using a 3D goethite–spongin-modified carbon paste electrode is reported. The prepared electrode exhibited excellent electrochemical catalytic activity towards DA and TRP oxidation. The electrochemical sensing of the modified electrode was investigated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Through differential pulse voltammetry analysis, two well-separated oxidation peaks were observed at 28 and 77 mV, corresponding to the oxidation of DA and TRP at the working electrode, with a large peak separation of up to 490 mV. DA and TRP were determined both individually and simultaneously in their dualistic mixture. As a result, the anodic peak currents and the concentrations of DA and TRP were found to exhibit linearity within the ranges of 4–246 μM for DA and 2 to 150 μM for TRP. The detection limits (S/N = 3) as low as 1.9 μM and 0.37 μM were achieved for DA and TRP, respectively. The proposed sensor was successfully applied to the simultaneous determination of DA and TRP in human urine samples with satisfactory recoveries (101% to 116%). [ABSTRACT FROM AUTHOR]

Electrochemical sensors and biosensors are today important analytical and monitoring tools in various fields, from agriculture and the food industry to environmental and biomedical/pharmaceutical applications. In particular, the integration of nanotechnology with electrochemical sensors and biosensors to develop a new generation of sensor platforms has made enormous progress in recent years. The outstanding properties of one‐dimensional (1D) nanofibers (NFs), such as high porosity, superior mechanical properties and high specific surface area have made them attractive electrocatalysts, support materials for the immobilization of biomolecules as well as mimetic materials for sensing and biosensing applications. Moreover, the possibility of fabricating multifunctional composites based on NFs increases (bio)sensing capabilities through synergistic effects and additive properties. This review describes the progress made over the last decade in the use of multifunctional NFs‐based composites as modified electrodes for the sensing of various analytes in biomedical, food, and wastewater treatment applications. The aim of this review is to provide a comprehensive overview and a guide for researchers from different disciplines to fabricate and improve their selective NFs‐based (bio)sensor platforms for the detection of desired analytes or multi‐analytes. [ABSTRACT FROM AUTHOR]

Azaperone is a very important phenylbutanone-based neurotransmitter used in the treatment of some animal (veterinary) clinics. This compound has various nerve and tendon stabilizing agents on livestock and animals. Muscular injection of azaperone is used to reduce stress in livestock and reduce their acting. In the present work, Fe3O4@SiO2-NH2/CS2 nanocomposite was synthesized and thoroughly characterized using FE-SEM, FT-IR, and XRD technique. The glassy carbon electrode was then modified with nanocomposite to fabricate a sensor named GCE/Fe3O4@SiO2-NH2/CS2. The application of modified electrode was tested for analysis of azaperone in ostrich meat and rat plasma. The electrochemical behavior of azaperone was tested using differential pulse and cyclic voltammetry. In Briton–Robinson buffer solution (pH = 6), azaperone had an oxidation peak at 0.82 V. Cyclic voltammetry studies indicated that the azaprone oxidation process on the modified electrode is irreversible. Experimental variables, including pH and accumulation time were optimized by monitoring the cyclic voltammetry responses toward azaperone peak current. Measurement of azaperone by differential pulse voltammetry technique showed linearity of anodic peak current vs. azaperone concentration in a range of 0.01–100.0 μM with detection and quantification limits of 3 nM and 10 nM, respectively. Also, the effect of disturbance of some species as possible interferers on the electrochemical response of azaperone was checked out. Finally, the capability of the fabricated sensor for azaperone measurement was successfully tested in ostrich meat and rat plasma as real samples. [ABSTRACT FROM AUTHOR]

Polymer composites based on graphene/carbon nanotubes (G/CNT) and reduced graphene oxide/carbon nanotubes (rGO/CNT) were synthetized by in‐situ miniemulsion polymerization containing 1 wt% hybrid filler with different ratio of G and CNT (10:1, 1.1, 1:10). From the hybrid aqueous dispersions obtained in that way polymer films were spontaneously formed at ambient conditions by water evaporation. The effect of the type of the graphene filler, G or rGO, on the properties and performance of polymer composites was studied. It was shown that G/CNT based composites presented improved morphology of the film due to better distribution of the filler and more organized structure of the film than that of rGO/CNT composites. The surface of the film was much smoother indicating more deepen filler within the polymer. Consequently, the G/CNT/polymer composites presented one order of magnitude increased Young's moduli and 60% lower water uptake than the neat polymer. Even though rGO/CNT/polymer composites presented also improved mechanical resistance, their water resistance was compromised probably due to the presence of hydrophilic functional groups that facilitated the water diffusion within the film. [ABSTRACT FROM AUTHOR]