Nickel -doped iron oxide nanoparticle-conjugated porphyrin interface (porphyrin/Fe2O3@Ni) for the non-enzymatic detection of dopamine from lacrimal fluid

Copper-Based Electrochemical Sensor Derived from Thiosemicarbazide for Selective Detection of Neurotransmitter Dopamine

This paper presents the synthesis of the ligand 1-picolinoyl-4-cyclohexyl-3-thiosemicarbazide (H2pctc) and new metal complexes [Ni(Hpctc)2] (1), [Cu(Hpctc)Cl] (2), and [Cd(Hpctc)2] (3). The synthesized metal complexes were precisely characterized using single crystal X-ray diffraction (SC-XRD). In addition, complexes 1-3 were also characterized by UV-vis, fluorescence, and infrared spectroscopy. SC-XRD data confirmed the distorted octahedral geometry around the Ni(II) and Cd(II) centers and the distorted square planar geometry around the Cu(II) center. Data derived from the emission spectra depict that higher fluorescence intensity was exhibited by complexes 1, 2, and 3 in comparison to that of the free ligand H2pctc, and complex 3 showed the maximum intensity. Further, these metal complex-modified GCEs (glassy carbon electrodes) were utilized for electrochemical sensing of dopamine (DPM). The electrochemical studies of these complexes were performed using modified glassy carbon electrodes supported by electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. In contrast to complexes 1 and 3, complex 2 is a superior electrode material with a high effective surface area for the electrochemical oxidation of DPM, according to the electrochemical response results. The derived sensor had a wide linear detection range of 1 to 1400 μM, an acceptable sensitivity of 0.01531 μA cm-2 μM-1, and a low LOD of 0.38 μM. The proposed approach was free of the interfering effects of ascorbic acid, uric acid, aminophenol, and other substances. During the successive scans, no fouling of the electrode surface was observed. The proposed electrochemical sensor had excellent stability, sensitivity, and a low detection limit making it suitable for the analysis of a variety of real samples. Additionally, it was proven to be useful for analyzing biological fluids.

Iron-selenide-based titanium dioxide nanocomposites as a novel electrode material for asymmetric supercapacitors operating at 2.3 V

This study portrays a facile wet-chemical synthesis of FeSe2/TiO2 nanocomposites for the first time for advanced asymmetric supercapacitor (SC) energy storage applications. Two different composites were prepared with varying ratios of TiO2 (90 and 60%, symbolized as KT-1 and KT-2) and their electrochemical properties were investigated to obtain an optimized performance. The electrochemical properties showed excellent energy storage performance owing to faradaic redox reactions from Fe2+/Fe3+ while TiO2 due to Ti3+/Ti4+ with high reversibility. Three-electrode designs in aqueous solutions showed a superlative capacitive performance, with KT-2 performing better (high capacitance and fastest charge kinetics). The superior capacitive performance drew our attention to further employing the KT-2 as a positive electrode to fabricate an asymmetric faradaic SC (KT-2//AC), exceeding exceptional energy storage performance after applying a wider voltage of 2.3 V in an aqueous solution. The constructed KT-2/AC faradaic SCs significantly improved electrochemical parameters such as capacitance of 95 F g-1, specific energy (69.79 Wh kg-1), and specific power delivery of 11529 W kg-1. Additionally, extremely outstanding durability was maintained after long-term cycling and rate performance. These fascinating findings manifest the promising feature of iron-based selenide nanocomposites, which can be effective electrode materials for next-generation high-performance SCs.

2D MXene-Based Biosensing: A Review

MXene emerged as decent 2D material and has been exploited for numerous applications in the last decade. The remunerations of the ideal metallic conductivity, optical absorbance, mechanical stability, higher heterogeneous electron transfer rate, and good redox capability have made MXene a potential candidate for biosensing applications. The hydrophilic nature, biocompatibility, antifouling, and anti-toxicity properties have opened avenues for MXene to perform in vitro and in vivo analysis. In this review, the concept, operating principle, detailed mechanism, and characteristic properties are comprehensively assessed and compiled along with breakthroughs in MXene fabrication and conjugation strategies for the development of unique electrochemical and optical biosensors. Further, the current challenges are summarized and suggested future aspects. This review article is believed to shed some light on the development of MXene for biosensing and will open new opportunities for the future advanced translational application of MXene bioassays.

Functionalized thiazolidone-decorated lanthanum-doped copper oxide: novel heterocyclic sea sponge morphology for the efficient detection of dopamine

Herein, we synthesized lanthanum (La)-doped sea sponge-shaped copper oxide (CuO) nanoparticles and wrapped them with novel O-, N- and S-rich (2Z,5Z)-3-acetyl-2-((3,4-dimethylphenyl)imino)-5-(2-oxoindolin-3-ylidene)thiazolidin-4-one (La@CuO-DMT). The shape and composition of the designed materials were confirmed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and Raman spectroscopy. The graphitic pencil electrode (GPE) fabricated using La@CuO-DMT showed excellent sensing efficacy against dopamine (DA) with good selectivity, reproducibility and ideal stability. The unique morphology and massive surface defects by La@CuO offer good accessibility to DA and enhance smooth and robust channeling of electrons at the electrode-electrolyte interface. Consequently, these properties resulted in improved reaction kinetics and robust DA oxidation with an amplified faradaic response. Meanwhile, O-, N-, and S-enriched carbon support, i.e. DMT, inhibited the leaching of electrode matrixes, resulting in a superior detection limit of 423 nm and an improved sensitivity of 13.9 μA μM-1 cm-2 in the linear range of 10 μM to 1500 μM. Additionally, the developed sensing interface was successfully employed to analyze DA from tear samples with excellent percentage recoveries. We expect that such engineered morphology-based nanoparticles with a O-, N-, and S-rich C support will facilitate the development of DA sensors for in vitro screening of rarely studied tear samples with good sensitivity and selectivity.