Functionalization of a carbon nanofiber with a tetrasulfonatophenyl ruthenium(II)porphine complex for real-time amperometric sensing of chlorpromazine.

A carbon nanofiber functionalized with ruthenium(II)-tetrasulfonato phenyl porphine (CNF/Ru-TSPP) is shown to be viable sensor for amperometric determination of the antipsychotic drug chlorpromazine (CPZ). The hollow platelet structured Ru-TSPP combines with the hollow cylindrical tube-like structure of the CNF via π stacking interaction. The morphological and electro conductive properties of the electrode were characterized by spectrophotometric techniques. The CNF/Ru-TSPP modified electrode displays a large surface-to-volume ratio, good electron transport and good electrocatalytic activity. The amperometric sensor, typically operated at a potential 0.63 V (vs. Ag/AgCl) exhibits a linear response in the 0.6 nM to 1.1 mM CPZ concentration range, has a 0.2 nM detection limit, and a remarkably good electrochemical sensitivity (2.405 µA µM-1 cm-2). The sensor is selective, repeatable and reproducible. It was successfully applied to the determination of CPZ in spiked serum samples. Graphical abstract Schematic presentation of carbon nanofiber/ tetrasulfonatophenyl Ruthenium(II)porphine (CNF/Ru-TSPP) nanocomposite synthesis and application for the electrochemical determination of chlorpromazine (CPZ).

Innovative Strategy Based on a Novel Carbon-Black-ß-Cyclodextrin Nanocomposite for the Simultaneous Determination of the Anticancer Drug Flutamide and the Environmental Pollutant 4-Nitrophenol.

In the present work, a noncovalent and eco-friendly approach was proposed to prepare a carbon-black/ß-cyclodextrin (CB/ß-CD) nanocomposite. CB/ß-CD-nanocomposite-modified screen-printed carbon electrodes were applied for the simultaneous determination of the anticancer drug flutamide (Flut) and the environmental pollutant 4-nitrophenol (4-NP). The electrochemical performance of the proposed sensor relied on the conductivity of CB, the different binding strengths of the guests (Flut and 4-NP) to the host (ß-CD), and the different reduction potentials of the nitroaromatic compounds. Fascinatingly, the proposed sensor exhibited an excellent electrochemical performance with high sensitivity, selectivity, and reproducibility. The obtained wide linear ranges were 0.05-158.3 and 0.125-225.8 µM for Flut and 4-NP. The low detection limits of 0.016 and 0.040 µM with the higher sensitivities of 5.476 and 9.168 µA µM-1 cm-2 were achieved for the determination of Flut and 4-NP, respectively. The practical feasibility of the proposed sensor was studied in tap-water and human-serum samples.

Novel in-situ encapsulation of tin phosphide particles in MXene conductive networks as anode materials of the durable sodium-ion battery.

Sodium-ion battery (SIB) is one of potential alternatives to lithium-ion battery, because of abundant resources and lower price of sodium. High electrical conductivity and long-term durability of MXene are advantageous as the anode material of SIB, but low energy density restricts applications. Tin phosphide possesses high theoretical capacity, low redox potential, and large energy density, but volume expansion reduces its cycling stability. In this study, tin phosphide particles are in-situ encapsulated into MXene conductive networks (SnxPy/MXene) by hydrothermal and phosphorization processes as novel anode materials of SIB. MXene amounts and hydrothermal durations are investigated to evenly distribute SnxPy in MXene. After 100 cycles, SnxPy/MXene reaches high specific capacities of 438.8 and 314.1 mAh/g at 0.2 and 1.0 A/g, respectively. The capacity retentions of 6.0% and 73.6% at 0.2 A/g are respectively obtained by SnxPy and SnxPy/MXene. The better specific capacity and cycling stability of SnxPy/MXene are attributed to less volume expansion of SnxPy during charge/discharge processes and relieved self-stacking of MXene by encapsulating SnxPy particles between MXene layers. Electrochemical impedance spectroscopy and Galvanostatic intermittent titration technique are also applied to analyze the charge storage mechanism in SIB. Higher sodium ion diffusion coefficient and smaller charge-transfer resistance are obtained by SnxPy/MXene.

Enhanced photocurrent density for photoelectrochemical catalyzing water oxidation using novel W-doped BiVO4 and metal organic framework composites.

Doping heteroatoms and decorating co-catalyst are intensively applied to improve photocatalytic ability of BiVO4. In this study, it is the first time to design W-doped BiVO4 coupling MIL-101(Fe) as photocatalyst for water oxidation using electrodeposition and hydrothermal processes. Similar system with Mo as dopant has been reported, but the dopant plays important roles on electrochemical performance. It is worthy to study the efficient system with different dopant. Doping amount of W is optimized to achieve high carrier density without creating serious recombination sites. MIL-101(Fe) is decorated on W-doped BiVO4 to suppress surface recombination, create accessible active sites and improve water oxidation kinetics. Optimized W-doped BiVO4/MIL-101(Fe) electrode shows a high photocurrent density of 4.00 mA/cm2 at 1.23 V versus reversible hydrogen electrode (VRHE) under air mass 1.5-global simulated light illumination without hole scavenger in electrolyte, due to large electrochemical surface area, high carrier density and small charge-transfer resistance. The W-doped BiVO4 and BiVO4 electrodes merely show photocurrent densities of 2.96 and 1.72 mA/cm2 at 1.23 VRHE, respectively. Photocurrent retention higher than 95.5% is obtained for W-doped BiVO4/MIL-101 (Fe) electrode under continuous illumination for 6300 s, suggesting lasting photocatalytic ability of this novel W-doped BiVO4/MIL-101(Fe) electrode.

Electroactive polypyrrole-molybdenum disulfide nanocomposite for ultrasensitive detection of berberine in rat plasma.

Electroactive polypyrrole-molybdenum disulfide (MoP) nanocomposites were synthesized and used for modifying screen-printed carbon electrodes (SPCEs) for ultrasensitive detection of berberine, an anticancer drug, in rat plasma. The electroactive nanocomposites were fabricated by exfoliating MoS2 followed by pyrrole polymerization. The effect of polypyrrole in the MoP nanocomposite was evaluated by varying the pyrrole concentration during polymerization, and the resulting nanocomposites prepared with pyrrole concentrations of 10, 20, 30 µL were named as MoP-1, MoP-2, and MoP-3, respectively. The electrochemical characterization of the three MoP nanocomposite sensors revealed that MoP-2/SPCE exhibited the highest electroactivity. The detection of berberine by the three MoP-coated SPCEs revealed that MoP-2/SPCE exhibited the highest activity against berberine due to a two-electron transfer mechanism on the MoP-2/SPCE electrode surface. The detection limit of berberine using the MoP-2/SPCE sensor was found to be about 0.05 µM, which is remarkably lower than the reported detection limits. The interference study proved the selectivity of the MoP-2/SPCE sensor toward berberine in the presence of other bioactive molecules and metal ions. The designed MoP-2/SPCE sensor retained 92% of its initial activity after 15 days of storage at room temperature, with RSD values of about 2.95% and 3.68% for the repeatability and reproducibility studies. Finally, the detection limit of berberine in a rat plasma sample determined using the MoP-2/SPCE sensor was found to be about 5 µM.

Facile one-pot sonochemical synthesis of Ni doped bismuth sulphide for the electrochemical determination of promethazine hydrochloride.

The present work reports the facile and cost-effective synthesis of rod like structured nickel doped bismuth sulphide (Ni-Bi2S3) via the ultrasonication process. The sonochemical synthesis technique is rapid, simple, non-explosive, and harmless than other conventional synthesis technique. After the synthesis, the resultant material was characterized through the various spectrophotometric techniques including FESEM, EDX, XRD, XPS and EIS. After the structural evaluation, as-synthesized Ni-Bi2S3 was applied for the electrocatalytic detection of promethazine hydrochloride (PMTZ) using CV and amperometry (i-t) techniques. Captivatingly, excellent electrocatalytic performance with the wider linear range from 1 nM to 163.17 µM was obtained for the electrochemical determination of PMTZ. The limit of detection (LOD) and sensitivity calculated around 0.4 nM and 2.904 µA µM-1 cm-2, respectively. Besides, an excellent selectivity, satisfactory reproducibility and good stability of the Ni-Bi2S3 modified electrode were checked towards the electrochemical determination of PMTZ. Furthermore, the real time application of PMTZ sensor was established in human serum and urine samples.

Rational design and facile synthesis of binary metal sulfides VS2-SnS2 hybrid with functionalized multiwalled carbon nanotube for the selective detection of neurotransmitter dopamine.

In this work, we report a sensitive and selective electrochemical sensor for the detection of dopamine (DA) neurotransmitter based on VS2-SnS2/f-MWCNT hybrids. Herein, the binary metal sulfide (VS2-SnS2) was synthesized via single step hydrothermal route and hybrids with f-MWCNT via the ultrasonication process. The as-prepared VS2-SnS2/f-MWCNT hybrids were characterized through the FESEM, EDX and elemental mapping, TEM, XPS, Raman and XRD techniques. The electrochemical performance and catalytic activity of the modified electrodes were probed using electrochemical impedance spectra (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Interestingly, DPV results exhibits an appreciable linear range from 0.025 to 1017 µM and LOD of 0.008 µM. The selectivity study was performed to prove the high selectivity of the VS2-SnS2/f-MWCNT hybrids modified electrode. Furthermore, the practical applicability of the DA sensor was scrutinized in human serum sample and rat brain sample.

Exploring the promising potential of MoS2-RuS2 binary metal sulphide towards the electrocatalysis of antibiotic drug sulphadiazine.

Benefiting from the rich redox chemistry, high electrical conductivity and synergistic effect from two metal ions, the binary metal sulphides received tremendous attention in various applications. As a result, the MoS2-RuS2 nanomaterial was synthesized through the simple one-pot hydrothermal technique. The electrocatalytic activity of the as-synthesized nanomaterial was exploited towards the electrochemical detection of antibiotic drug sulphadiazine (SDZ). The electrocatalytic oxidation of the SDZ exhibited lowest anodic peak potential and ehanced anodic peak current rather than other modified electrodes. Notably, an excellent electrochemical performance with very lowest limit of detection (LOD) of 0.004 µM, appreciable linear range from 0.01 µM to 598.7 µM and high sensitivity (2.333 µA µM-1 cm-2) was obtained at MoS2-RuS2 modified electrode. Moreover, well anti-interfering property, good operational stability, repeatability and reproducibility was achieved. Facinatingly, the practicability of the modified electrode demonstrated in milk and human serum samples.

Electrochemical co-preparation of cobalt sulfide/reduced graphene oxide composite for electrocatalytic activity and determination of H2O2 in biological samples.

In this work, we describe a simple approach for the preparation of cobalt sulfide/reduced graphene oxide (CoS/RGO) nanohybrids via single step electrochemical method. The electrocatalytic activity of the CoS/RGO nanohybrids was evaluated towards the detection hydrogen peroxide (H2O2). The physiochemical properties of the prepared composite was characterized by means of field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray powder diffraction patterns. The CoS/RGO modified electrode showed superior electrocatalytic activity towards the detection of H2O2. The amperometric (i-t) studies revealed that the CoS/RGO performed well by attaining a wide linear response range of H2O2 from 0.1 to 2542.4µM with a lower detection limit 42nM and the sensitivity of 2.519µAµM-1cm-2. Meanwhile, the CoS/RGO nanohybrids exhibited good selectivity, rapid and stable response towards H2O2. The practical applicability of the sensor was successfully evaluated in human serum and urine samples with satisfactory recoveries.

Highly sensitive electrochemical detection of palmatine using a biocompatible multiwalled carbon nanotube/poly-l-lysine composite.

To date, the natural alkaloids are mostly used in the field of pharmacological applications and the active substance of palmatine was extensively used in cancer therapy and other biomedical applications. Hence, in this study we report a simple preparation of poly-l-lysine (PLL) electro-polymerized on the surface of functionalized multiwalled carbon nanotubes (f-MWCNT) for electrochemical detection of palmatine content in human serum and urine samples. The active amino group of PLL plays a vital role towards the oxidation palmatine and exhibits superior electrocatalytic activity. Under optimum conditions, the prepared f-MWCNT/PLL composite shows a wide linear response range over the palmatine concentration ranging from 0.5µM to 425µM, and a detection limit (LOD) of 0.12µM based on S/N =3 (signal to noise ratio). The real time monitoring of palmatine content in serum and urine samples displays an appropriate recoveries and excellent performance for the practical analysis. The advantage of this developed system was simple, higher electrocatalytic activity, long-term stability and low cost. We hope that the prepared composite opens a new way for the fabrication of different biosensors in the field of biomedical application.

Green reduction of reduced graphene oxide with nickel tetraphenyl porphyrin nanocomposite modified electrode for enhanced electrochemical determination of environmentally pollutant nitrobenzene.

Nitrobenzene (NB) is widely used in the manufacturing of different types of products and other aromatic chemicals. Moreover, it is highly toxic and environmental pollutant compound. Therefore, the detection of nitro aromatic compounds (NACs) has gained more attention in the field of sensor. This article describes the green reduction utilized to preparation of green reduced graphene oxide/nickel tetraphenyl porphyrin (GRGO/Ni-TPP) nanocomposite modified electrode for the determination of nitrobenzene (NB). The GRGO was prepared by environmentally friendly method and using caffeic acid (CA) as a reducing agent. Moreover, the GRGO/Ni-TPP nanocomposite was prepared via the π-π stacking interaction between the RGO and Ni-TPP. In addition, the prepared material was confirmed by the UV-Visible spectroscopy (UV), nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). The structural morphology and elemental composition of the prepared nanocomposite was confirmed by the scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Besides, the electrochemical studies of the prepared nanocomposite was characterized by the CV and DPV technique. The DPV studies displayed the linearity response of the proposed sensor about 0.5-878µM with the sensitivity of 1.277µAµM-1cm-2 and the limit of detection (LOD) is 0.14µM. Furthermore, the GRGO/Ni-TPP nanocomposite modified electrode shows good selectivity towards the detection of NB. In addition, the real sample analysis exhibited appreciable recovery towards the determination of NB using various types of water samples.