Linear Sweep Voltammetric Research Articles

Synthesis and electrochemial performances of CuO/MgO nanocomposite as a sensing platform for dopamine

In this line of work, we reported the sensing of Dopamine (DA) with the existence of Ascorbic acid (AA) and Uric acid (UA) by CuO/MgO nanocomposite fabricated to carbon paste electrode (MCPE) by Cyclic voltammetric (CV) and Linear Sweep Voltammetric (LSV) techniques. CuO nanoparticles was symphonized by simple co-precipitation method and MgO was symphonized by mechanochemical method. The characterisation such as scanning electron microscope (SEM), X-Ray diffraction (XRD) and energy dispersive X-Ray spectroscopy (EDS) was reported for both the nanoparticles. Certain parameters inclusive of varying scan rate, concentration of analytes, pH of the solution were developed to the modified electrode. The detection and quantification limits (LOD and LOQ) value was calculated. Simultaneous analysis of DA in the subsistence of AA and UA was failed at unmodified carbon paste electrode (CPE) but a well defined separation of anodic peaks occurred at CuO / MgO nanocomposite fabricated carbon paste electrode. The method has been applied to spiked injection sample and blood serum. Thus the presented method can be successfully employed for the scrutining of DA in the real samples.

A computer-generated plan to develop an intelligent biosensor for investigation of the inhibition of renin by aliskiren: A journey from inhibition to biosensing

For the first time, a novel electrochemical biosensor was fabricated based on modification of a rotating glassy carbon electrode with multi-walled carbon nanotubes-ionic liquid, and molecularly imprinted polymers (MIPs) in which renin (Rn), and aliskiren (AK) were used as templates. By immersion the biosensor in Rn, AK, and their binary system (AK-Rn) solutions, the species (Rn, AK, and AK-Rn) were entrapped within the pathways of the MIPs. These processes and investigation of the inhibition of the Rn by AK helped us to obtain higher electrochemical signals for a good monitorization of the system. The effects of experimental parameters on response of the biosensor to AK were optimized by a small central composite design to obtain the highest response. Hydrodynamic cyclic voltametric (HCV), hydrodynamic differential pulse voltammetric (HDPV), and hydrodynamic linear sweep voltammetric (HLSV) data obtained and recorded in order to be analyzed by classical methods and multivariate curve resolution-alternating least squares (MCR-ALS) as an advanced chemometric method. The results of molecular dockings, classical and chemometric analyses confirmed that the Rn was strongly inhibited by the AK which was good evidence to develop a novel biosensing system for determination of Rn. A novel biosensor was developed for determination of the Rn which had an acceptable performance in determination of Rn in the range of 0–9 fM. This approach opened a new way for investigation of enzymes' inhibition, and developing a new generation of electrochemical biosensors for medical and biomedical applications.

Label-free immunosensor for detection of hepatitis C (HCV) core antigen using ternary polypyrrole-Ag doped ZnO-exfoliated graphene nanocomposite

A label-free immunosensor for detection of hepatitis C (HCV) core antigen was fabricated using a ternary nanocomposite based on polypyrrole (PPy), silver doped zinc oxide (Ag-ZnO) and exfoliated graphene (Ex-Gr). The negatively charged anticore mAbs 19D9D6 (1 NLB monoclonal antibodies) were immobilized at the PPy/Ag-ZnO/Ex-Gr 9 % nanocomposite surface as it is suitable for non-covalent (electrostatic) immobilization for fabricating the label-free immunosensor. The isoelectric point (IEP) achieved at around pH 7 for PPy shifts to the lower value of pH 5.75 for PPy/Ag-ZnO/Ex-Gr 9 % nanocomposite. The linear sweep voltammetric (LSV) analysis of the as-prepared samples indicate high electrochemical activity. Similarly, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry confirmed the hindrance in the faradaic processes due to the presence of the interfacial biomolecules layer, after surface modification confirming the fabrication of the immunosensor. The LSV current signal response decrement for the concentration range of antigen [HCV core nucleocapsid polypeptide (residues 13–40) (RNTNRRPQ DVKFPGGGQI VGGVYLLPRR)] ranging from 0.001 ng mL-1 to 200 ng mL-1 was performed depicting the hindrance to electron transfer increases with increase in the antigen concentration as antigen antibody interaction takes place thickening the insulative layer of biomolecules at the interface leading to gradual decrease in the current response. The limit of detection was measured to be approximately 0.41 pg mL-1, respectively (S/N = 3). The single interfering protein doesn’t decrease the LSV current response for HCV (50 ng mL-1) depicting the immunospecificity i-e selectivity of the fabricated immunosensor. The as prepared label-free immunosensor displayed lower limit of detection, high selectivity and stability.

Highly sensitive amperometric food sensor for Sudan-I dye using nanocomposites modified working electrode

Sudan-I dye (1-phenyl azo-2-naphthol) is commonly used as a coloring agent in the food and textile industries. The excessive use of Sudan-I dye has ill effects on human health. A sensitive and selective electrochemical detection is required for sensing Sudan-I dye in food products. An electrochemical sensor based on a modified working electrode using ternary mixed metal oxide (Ti/Fe/CuO) nanocomposites was developed for sensing Sudan-I dye. Using a modified Sol-gel technique, Ti/Fe/CuO mixed metal nanocomposites were synthesized. FT-IR, UV–Visible, SEM, and XRD techniques were used to characterize the Ti/Fe/CuO nanocomposites. Different voltammetric techniques, such as Cyclic voltammetry (CV), Differential Pulse Voltammetry (DPV), and Linear Sweep Voltammetric (LSV) were used for qualitative and quantitative estimation of Sudan-I dye. Electrochemical Impedance Spectroscopy (EIS) was used for structural information of interface. The specially designed working electrode acted as a sensor and shows good sensing ability toward Sudan-I dye in real food samples. A linear range of 0–160 µM and 0–200 µM for red chili sauce and powder (real samples), respectively was observed. Under the optimized condition, the current response was linear with a detection limit of 0.02 µM/L. A characteristic oxidation peak of 7263.36 µA at 0.2606 V and a reductive peak of − 1465 μA at − 0.3714 V are the characteristic peaks for Sudan-I dye. The effect of change in pH, scan rate, storage, stability behavior, and concentration of Sudan-I dye was evaluated. A comparative study was done between glassy carbon electrodes, bare Copper metal, and ternary metal oxide NCs modified electrodes. The developed electrochemical sensor demonstrated reliability, reproducibility, stability, speed, and non-specificity, making it suitable for both quantitative and qualitative analysis of food additives, preservatives, coloring agents, and flavoring agents.

A novel triple templates molecularly imprinted biosensor assisted by second-order calibration methods based on generation of second-order hydrodynamic linear sweep voltammetric data for simultaneous biosensing of insulin, proinsulin and C-peptide: Application to comparing PARAFAC2 and PARASIAS

In this work, a novel, very sensitive and selective electrochemical biosensor was fabricated based on excellent modification of a thick-film boron doped diamond electrode (TFBDDE) for simultaneous biosensing of insulin (IN), proinsulin (PIN) and C-peptide (CPT). The TFBDDE was modified with multiwalled carbon nanotubes-fullerene C60-graphene-ionic liquid (MWCNTs-C60-GR-IL). Then, IN, PIN and CPT as template molecules were mixed with N-methacryloyl-(L) 3-histidine methyl ester, 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate, and drop-casted onto the sensor surface for the synthesis of triple templates molecularly imprinted polymers (TTMIPs) by ultraviolet polymerization method. After individual immersion of the biosensor with IN, PIN and CPT, its hydrodynamic linear sweep voltammetric (HLSV) responses were recorded. Immersion of the biosensor in a ternary solution of IN, PIN and CPT generated a single HLSV response which forced us to use multi-way calibration methods for simultaneous determination of IN, PIN and CPT based on generation of second-order HLSV data at different step potentials. Building three-way calibration models by PARAFAC2 and PARASIAS was performed, and the results confirmed superiority of PARASIAS than PARAFAC2 in simultaneous determination of IN, PIN and CPT in the ranges of 1–16 pM, 4–25 pM and 8–88 pM, respectively, in both artificial and real human serum samples. According to the results obtained in this work, the biosensor assisted by PARASIAS can be used as a reliable device for simultaneous determination of IN, PIN and CPT in serum samples.

Electrocatalytic Reduction of Nitrogen to Ammonia By Janus Wsse Nanowalls

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have been made in improving the NRR for the significant effort in catalytic activity due to its unique crystal structures, electronic properties, and promising nonprecious catalysts. However, many studies have provided solutions to activate the inert basal plane with low improvement. With highly asymmetric configuration, Janus monolayer with intrinsic strain and electric field can enable a way to tune the activity in TMDs-based catalysts. Although the first successful experimental synthesis of Janus structure (MoSSe) has gained significant interest and become a fast-growing TMDs-based material, the structure remains limited in the low dimensional and hard to expose the edges site to enhance the catalytic activity. Besides the common benefits of 2D TMDs, such as high surface area, short carrier migration distance, and tunable electronic structure. In this regard, the inherent structural asymmetry of Janus WSSe nanowalls as a new means to enhance the NRR activity was investigated. Janus TMDs nanowalls as the catalyst by taking advantage of its introduction of in-gap states with a shift in the Fermi level in nitrogen adsorbed system because of Janus asymmetry from the origin of stimulating NRR activity. Raman spectra showthe related main modes for WSSe Janus structure as shown in Fig. 1a, for which peaks at 271 and 333 nm can be found, respectively. The linear sweep voltammetric (LSV) curves of the catalysts as shown in Fig. 1b confirm the onset potential of the NRR, which increases with the different materials. Janus WSSe Janus nanowalls exhibit outstanding NRR performance over its parent materials (WS2 and WSe2). The results should propose a new path to design high performance and a novel structure for Janus TMD-based catalysts.Fig1. (a) Evolution of Raman spectra in the WSSe nanowalls as a function of chemical composition (b) LSV curves for WS2, WSe2, WS2-XSe2-2X alloy, and WSSe Janus nanowalls Figure 1

Hydrothermal synthesis of nanostructured NiO for hydrazine sensing application

In last few years, nickel oxide (NiO) has been widely explored in different optoelectronic applications. Herein, we reported synthesis of nanostructured NiO under facile conditions. The prepared nanostructured NiO was characterized by advanced techniques (XRD, SEM, EDX, and XPS). Further, hydrazine (HZ) sensor was developed by modifying the bare active surface of glassy carbon electrode (GCE) using drop-casting approach. To detect the HZ, linear-sweep voltammetric (LSV) technique was utilized which showed good repeatability, stability, and selectivity. The modified GCE (NiO/GCE) acted as HZ sensor and demonstrated excellent detection limit (LOD) of 0.82 μM and sensitivity of 3.47 μA/μMcm2. In further investigations, real sample study indicated the potential role of NiO/GCE for practical applications.

Fabrication of GC-r-GO-PAMAM (G3)-Pd electrode for electro-catalytic oxidation of formic acid

Graphene functionalized with Poly(amidoamine) dendrimer stabilized PdNPs (r-GO-PAMAM-Pd) composite was prepared through facile experimental routes and characterized by FT-IR, XRD, Raman, SEM and EDAX techniques. Initially, poly(amidoamine) generation 3 (PAMAM (G3)) dendrimer was functionalized on graphene oxide (GO) and the resulting matrix was loaded with PdNPs through stabilization and thus produced excellent conducting composite material. The electro-catalytic activity of this composite was inspected by coating on bare GCE and thus produced stable and efficient GC-r-GO-PAMAM (G3)-Pd electrode and this in turn demonstrated for the oxidation of formic acid (FA). The occurrence of the oxidation reaction was monitored by cyclic voltammetric (CV) and linear sweep voltammetric (LSV) techniques in 0.5 M H2SO4 medium at the potential window of -0.3 to 1.0 V vs. Ag/AgCl, v = 50 mVs-1. The observed peak potential for the new electrode was located at 0.15V and compared with existing electrodes derived from different GO/Pd composites.The comparative results reveals that the newly designed electrode shown an excellent catalytic activity, more resistant to the surface poisoning and the anodic onset potential was more negative than the reported electrodes. This improved electro-catalytic performance are due to the contribution of synergetic effect of GO, dendrimer and PdNPs. Copyright © 2018 VBRI Press.

Simple Electrochemical Chloramphenicol Assay at a Disposable Pencil Graphite Electrode by Square Wave Voltammetry and Linear Sweep Voltammetry

Chloramphenicol (CAP) is a widely used, broad spectrum antibiotic that contains a nitrobenzene moiety with a possible poisonous feature. Thus, the development of low cost, simple, and rapid analytical methods for the reliable CAP quantification is necessary. Starting from the nitro group electroactivity, the cyclic voltammetric properties of CAP were investigated at the common commercially available, disposable pencil graphite electrode (PGE). The effect of the electrode material, the electrolyte pH and the potential scan rate were investigated. At 2H type PGE, the CAP cyclic voltammograms presented an anodic and two cathodic diffusion controlled, pH-dependent peaks, each involving the exchange of two electrons and two protons. Based on CAP main reduction peak at PGE in pH 5.00 Britton Robinson buffer, a square wave voltammetric (SWV) method was developed for its quantification from 2.50 × 10−6 to 7.50 × 10−4 mol L−1 with a limit of detection (LoD) of 1.39 × 10−6 mol L−1. Moreover, the anodic peak was also employed for the first time for a CAP linear sweep voltammetric (LSV) assay (2.50 × 10−6 to 1.00 × 10−3 mol L−1; LoD 6.09 × 10−7 mol L−1 CAP). Both voltammetric methods using the cost-effective PGE were applied for the determination of CAP in pharmaceuticals, obtaining recoveries of 100.9 ± 1.4% (relative standard deviation of 3.54%) for SWV and 100.7 ± 1.4% (relative standard deviation of 3.55%) for LSV.

Amorphous Ru-Pi nanoclusters decorated on PEDOT modified carbon fibre paper as a highly efficient electrocatalyst for oxygen evolution reaction

Amorphous Ru-Pi nanoclusters deposited on PEDOT modified carbon fibre paper electrode have been investigated as a potential oxygen evolution electrocatalyst. CFP/PEDOT/Ru-Pi electrode was prepared by electrodeposition of Ru-Pi nanoclusters on PEDOT decorated CFP using cyclic voltammetry (CV). Field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDS), attenuated total reflection with Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) were used for physicochemical characterization. Linear sweep voltammetric (LSV) studies corroborated that CFP/PEDOT/Ru-Pi has exhibited higher oxidation peak current when compared to other modified electrodes. CFP/PEDOT/Ru-Pi electrode has displayed better catalytic activity towards oxygen evolution reaction at low onset and over potential. The modified electrode has also offered better stability towards the oxidation reaction in phosphate buffer solution (PBS) and the working stability of these electrodes were determined using LSV and CV.

One-step hydrothermal synthesis of ZnO nanorods as efficient oxygen evolution reaction catalyst

To deal with rapid depletion of fossil fuels and increasing demand of energy, development of highly efficient non-noble metal based catalyst has attracted much attention. Therefore, in this study reported a facile one-step hydrothermal synthesis of ZnO nanorods. The structural and morphological properties of the synthesized sample have been studied through X-ray Diffraction analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, Scanning electron microscope, SEM-based Energy dispersive X-ray spectroscopy and Ultraviolet-visible spectroscopy. Electrochemical studies toward oxygen evolution reaction are evaluated via cyclic voltammetric measurements (CV) and linear sweep voltammetric (LSV) measurements. It has been found that ZnO-nanorods/nickel foam (NF) delivers benchmark 10 mA cm−2 at just 340 mV overpotential, which is superior than previously reported oxygen evolution reaction (OER) catalysts. The overall findings of the current study provide a cost-effective and efficient synthesis of ZnO-nanorods for application as an electrocatalyst.

Determination of Ivabradine by Linear Sweep, Square Wave and Differential Pulse Voltammetric Methods Using Platinum Electrode in Pharmaceutical Preparation

Objectives: In this study, simple, fast and reliable cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) methods were developed and validated for determination of ivabradine in pharmaceutical preparations. Methods: The proposed methods were based on electrochemical oxidation of ivabradine at platinum electrode in acetonitrile solution containing 0.1 M LiCIO4.The well-defined oxidation peak was observed at 1.34 V. Results: The calibration curves were linear for ivabradine at the concentration range of 5-40 µg/mL for LSV, SWV and DPV methods, respectively. Intra- and inter-day precision values for ivabradine were less than 3.12, and accuracy (relative error) was better than 4.78%. The limits of detection values ranged from 1.20 to 1.60 µg/mL and quantification from 3.60 to 4.80 µg/mL. The mean recovery of ivabradine was 99.9% for pharmaceutical preparation. No interference was found from tablet excipients at the selected assay conditions. Conclusion: Developed methods in this study are accurate, precise and can be easily applied to Coralan tablet as pharmaceutical preparation.

Introduction of a thrombin sensor based on its interaction with dabigatran as an oral direct thrombin inhibitor

Dabigatran (DAB) is a direct thrombin inhibitor used for preventing blood clots and emboli after orthopedic surgery. The DAB - thrombin interaction was followed by fluorescence and UV–Vis spectroscopic methods. The binding of DAB to thrombin was also modeled by the molecular docking method. The obtained experimental results were consistent with theoretical results. The voltammetric method was also tested for DAB - thrombin interaction. Based on voltammetric findings, carbon paste electrode containing graphite powder, paraffin oil, MWCNTs, and DAB was constructed and used for thrombin monitoring after investigation of the DAB oxidation mechanism for the first time. The decrease in the linear sweep voltammetric (LSV) peak current of DAB in the presence of thrombin was utilized for the thrombin analysis. The calibration plot was linear in the concentration range of 1 to 70 nM (R2 = 0.9992) by LSV technique with a detection limit of 0.3 nM. The applicability of the proposed sensor was evaluated by the determination of thrombin in human serum as a real sample.

In-situ pyrolytic processed zinc stannate incorporated graphitic carbon nitride nanocomposite for selective and sensitive electrochemical determination of nitrobenzene

In this study describes the in-situ pyrolytic synthesis of zinc stannate-graphitic carbon nitride (ZSO-gCN) nanocomposite material and its potential application in electrochemical sensing of nitrobenzene. The ZSO-gCN nanocomposite was characterized by X-ray diffraction, fourier transform infra-red, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy and elemental mapping to determine the crystalline, morphology, and functionalities of the resultant nanocomposite material. The ZSO-gCN was used to modify the glassy carbon electrode (GCE) surface, and investigated for electrochemical determination of nitrobenzene. The ZSO-gCN modified GCE showed good electrocatalytic activity towards nitrobenzene than other modified electrodes. The ZSO-gCN/GCE having the electron transfer rate constant (ks = 0.746 s−1) and charge transfer coefficient (α = 1.171) towards electroanalysis of nitrobenzene. Linear sweep voltammetric (LSV) technique exhibits cathodic peak current increases in linearly with increasing nitrobenzene content in the range of 30–100 μM. The lowest detection limit (LoD) and sensitivity were found to be 2.2 μM (S/N = 3) and 0.05857 μA μM−1 cm−2, respectively. The inorganic species and organic substances such as Ca2+, K+ and 4-nitrophenol, 1-chloro,2,4-dinitrobenzene, 1-bromo,2-nitrobenzene, 1-iodo,2-nitrobenzene were showed negligible interference effect with nitrobenzene detection and good sensitivity for monitoring nitrobenzene content in real samples were acquired. This recently produced ZSO-gCN nanocomposite would be a prospective material for electrochemical based sensor applications.

Sensitive and selective voltammetric oxidation and determination of an antiemetic drug using gold electrode and its biomedical applications

In this study, we investigated the voltammetric oxidation and determination of an antiemetic drug, metoclopramide hydrochloride at gold electrode using cyclic, linear sweep and differential pulse voltammetric (DPV) techniques. The anodic peak was characterized and the process was diffusion-controlled. The influence of current on pH, scan rate, concentration was studied to optimize the experimental conditions. The number of electrons transferred was calculated and plausible oxidation mechanism was proposed. The ability of gold electrode to determine trace amount of MCP was studied using DPV. Limit of detection and quantification was calculated under the optimized conditions. For the analytical applications, pharmaceutical formulation and human urine sample analysis were performed. Various excipients were used to investigate their interference in the analytical application and it was found that the proposed method can be adopted for clinical trials, quality control and real sample analysis.

Voltammetric detection of anticancer drug Doxorubicin at pencil graphite electrode: A voltammetric study

In this work, focused on the characteristic of a pencil graphite electrode (PGE) as a voltammetric study to the electroanalysis of anticancer drug Doxorubicin (DOX) has been investigated. For PGE, detection sensitivity was determined by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and linear sweep voltammetric (LSV) techniques. In addition, the morphological structural feature of the PGE was characterized by scanning electron microscopy (SEM). Some of the most important effective parameters such as pH, sweep rate, and concentration of DOX were optimized at PGE by using CV, DPV and LSV techniques. A Plausible electrooxidation mechanism of DOX was proposed and successful selective separation of dopamine (DA) and DOX were achieved by using the above mentioned techniques. The applicability of the suggested method was illustrated by the investigation of DOX present in real sample analysis and the method can also be used in clinical analysis, quality control and routine verification of drugs in pharmaceutical formulations.

A Highly Reversible 5V-Class Li2CoPO4f/Graphite Battery

Introduction To increase the energy density of the Li-ion rechargeable batteries, a use of high-voltage cathode materials as well as their stable operating systems are of importance. However, the issues represented by degradation of the cathode materials, electrolytes, and other cell components have obstructed the development of a high-voltage system over past decade. Here, we report that concentrated LiBF4 in a mixed solvents, propylene carbonate (PC) and fluoroethylene carbonate (FEC), allows a stable cycling 5 V-class Li2CoPO4F/graphite full-cell for more than 600 cycles. In the presentation, the optimized cell components with special attention to the compatibility between the carbon conductive agents and electrolytes, will be discussed. Method The LiBF4-based electrolytes were prepared by mixing a certain amount of salt with solvents in an Ar-filled glove box. The Raman measurement was conducted to study the solution structure of the electrolytes. The linear sweep voltammetric (LSV) was performed to evaluate the anodic limits of the electrolytes with three-electrode cells consisting a Pt plate as a working electrode and Li metals as reference and counter electrodes. The carbon compatibility with the electrolytes was estimated using cyclic voltammetric (CV) with two-electrode cells of carbon electrode and Li metal. The transition metals deposited on the cycled graphite electrodes in the LCPF/graphite full-cells after charge and discharge test were analyzed by an Energy-dispersive X-ray spectroscopy (EDS). Results As a result of LSV measurement, the anodic current started to flow from 5.8 V (vs. Li/Li+) in the concentrated 1:1.8 LiBF4:PC/FEC (5/5,n/n), which was far higher than that in the commercial electrolyte of 1M LiPF6 EC/DMC (1/1,v/v). The Raman spectroscopy analysis presented that the concentrated LiBF4 PC/FEC electrolyte had an aggregate (AGG)-predominant solution structure. An upshift of bands corresponding to the anion and free solvent molecules was observed with an increase of salt concentration, denoting strengthened coordination of anion and solvents with Li+. Therefore, it was considered that the highest occupied molecular orbital (HOMO) level of the anion and solvents was decreased since the Li+ ion functioned as a strong Lewis acid that resulted in partial electron donation from the anion and solvents to the Li+ ion. Moreover, it was revealed that the main causes of cell deterioration at a high potential were (i) decomposition of electrolyte, (ii) anion intercalation into the carbon additives, and (iii) transition metal dissolution from cathode material. Especially, the carbon conductive agents with a low graphitization degree was selected to increase carbon compatibility with the electrolyte. It was because the anion intercalation occurred easily to the carbon additives with a high graphitization degree, leading to the damage of the graphene layers by continuously exposing the sites where were highly reactive with the electrolyte. Also, it was obvious that an intensified coordination between the anion and Li+ in the highly concentrated electrolyte helped to impede the anion intercalation reaction. The concentrated LiBF4 PC/FEC electrolyte and the optimized cell design including carbon conductive agents with a low graphitization degree were applied to a 5 V-class Li2CoPO4F/graphite system. As a result, a stable charge and discharge for more than 600 cycles was obtained. Besides, it was revealed that the concentrated electrolyte contributed to the stable operation of the high voltage battery by suppressing the transition metal dissolution from the cathodes. In conclusion, on the basis of the various design factors as noted above; (i) improvement of oxidation stability, (ii) impeding the anion intercalation, and (iii) suppression of transition metal dissolution, we succeed to obtain a stable reversible operation of the 5 V-class Li2CoPO4F/graphite full-cell for the first time. Figure 1

Tyramine Functionalized Graphene: Metal‐Free Electrochemical Non‐Enzymatic Biosensing of Hydrogen Peroxide

AbstractWe report here non‐enzymatic electrochemical biosensing of H2O2 using a highly stable, metal‐free, tyramine functionalized graphene (T‐GO) based electrocatalytic system. The surface functionalization of tyramine on graphene was carried out chemically. The obtained sheets were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) as well as X‐ray photoelectron (XP), Raman, FT‐IR and UV‐visible spectroscopy. More significantly, the combined results from morphological and structural studies show the formation of a few layers of graphene with effective large‐scale functionalization by tyramine. As a metal‐free electrocatalyst, the as‐synthesized T‐GO shown good electrocatalytic activity towards reduction of H2O2 with a sensitivity of 0.105 mM/cm2 confirmed by combined results from cyclic voltammetric (CV) and linear sweep voltammetric (LSV), and amperometric (i–t) measurements. The lower onset potential (−0.23 mV vs SCE), lower detection limit, wider concentration range (10 mM to 60 mM) with higher electrochemical current and potential stability demonstrated the potential of our non‐enzymatic and cost‐effective T‐GO based electrocatalytic system towards reduction of hydrogen peroxide.

Construction of Chitosan-Zn-Based Electrochemical Biosensing Platform for Rapid and Accurate Assay of Actin.

This work reports a study on the development of a sensitive immunosensor for the assay of actin, which is fabricated using sensing material chitosan-Zn nanoparticles (NPs) and anti-actin modified on glassy carbon electrode respectively. The prepared materials were characterized using transmission electron microscope (TEM), fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) spectra, and circular dichroism (CD) techniques. Meanwhile, the electrochemical properties were studied by linear sweep voltammetric (LSV), electrochemical impedance spectra (EIS), and differential pulse voltammetry (DPV). According to the experiments, under the optimum conditions, the linear fitting equation was I (μA) = −17.31 + 78.97c (R2 = 0.9948). The linear range was from 0.0001 to 0.1 mg/mL and the detection limit (LOD, S/N = 3) was 21.52 ng/mL. The interference studies were also performed for checking the sensors’ selectivity to actin. With better properties of the chitosan-Zn NPs, the modified electrode is considered as a better candidate than Western blot or immunohistochemical method for real-time usability. The detection limit reported is the lowest till date and this method provides a new approach for quality evaluation.

Graphite-like g-C3N4-F127-Au nanosheets used for sensitive monitoring of heat shock protein 90

In this paper, a novel immunosensor was built for quantitative detection of heat shock protein 90 (HSP90) based on graphite-like carbon nitride nanosheets (g-C3N4 NSs) hybridized with gold-F127 nanoparticles (g-C3N4-F127-Au NSs) modified electrode. The transmission electron microscope (TEM) was used to observe the structure and morphology of g-C3N4-F127-Au NSs. The successful preparation of g-C3N4-F127-Au NSs was characterized by UV–vis spectra, fourier transform infrared spectra (FTIR) and Raman spectra. Meanwhile, the electrochemical properties were measured by linear sweep voltammetric (LSV) and differential pulse voltammetry (DPV). Under the optimized conditions, the peak currents were linear with the concentration of HSP90 ranging from 3.5μg/mL to 2.43mg/mL. The linear regression equation was I (μA)=10.31–10.05logc (R2=0.9986, n=9) with the detection limit of 2.67μg/mL. Finally, the immunosensor exhibited good selectivity performance and provided a new approach for meat quality evaluation.