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Lignin valorization has attracted significant attention in recent years due to its abundance and potential as a renewable organic carbon resource to produce a variety of value-added chemicals and fuel additives. Catalytic upgrading of lignin faces challenges due to its complex structure and an active catalyst with selective surface properties is needed to break the stable C–O and C–C interunit linkages. In the present work, we developed a series of multifunctional Ru/NbOPO₄/TiO₂ catalysts with varying surface acidic properties and explored their potential upon hydrogenolysis of lignin model compound eugenol. Textural and surface acidic properties of the prepared materials were studied by means of different techniques such as N₂-physisorption, NH₃-TPD, XRD, SEM-EDS, Raman spectra, FT-IR, and TEM. Our catalytic results revealed synergistic role of acid and metal sites upon catalyst performance, whereupon high yields of hydrocarbons (86.9–100 wt.%) were obtained with selective cleavage of the methoxy and hydroxy groups under milder conditions. A kinetic study further identified the reaction mechanism and determined a rate law and partial reaction orders. This research advances the understanding of catalyst design for upgrading of the lignin or lignin monomers into value added chemicals. and on the other hand, contributes to sustainable development by maximizing biomass usage and providing environmentally friendly alternatives in renewable energy.

Enteroviruses are a vast genus of positive-sense RNA viruses that cause diseases ranging from common cold to poliomyelitis and viral myocarditis. They encode a membrane-bound AAA+ ATPase, 2C, that has been suggested to serve several roles in virus replication, e.g. as an RNA helicase and capsid assembly factor. Here, we report the reconstitution of full-length, poliovirus 2C’s association with membranes. We show that the N-terminal membrane-binding domain of 2C contains a conserved glycine, which is suggested by structure predictions to divides the domain into two amphipathic helix regions, which we name AH1 and AH2. AH2 is the main mediator of 2C oligomerization, and is necessary and sufficient for its membrane binding. AH1 is the main mediator of a novel function of 2C: clustering of membranes. Cryo-electron tomography reveal that several 2C copies mediate this function by localizing to vesicle-vesicle interfaces. 2C-mediated clustering is partially outcompeted by RNA, suggesting a way by which 2C can switch from an early role in coalescing replication organelles and lipid droplets, to a later role where 2C assists RNA replication and particle assembly. 2C is sufficient to recruit RNA to membranes, with a preference for double-stranded RNA (the replicating form of the viral genome). Finally, the in vitro reconstitution revealed that full-length, membrane-bound 2C has ATPase activity and ATP-independent, single-strand ribonuclease activity, but no detectable helicase activity. Together, this study suggests novel roles for 2C in membrane clustering, RNA membrane recruitment and cleavage, and calls into question a role of 2C as an RNA helicase. The reconstitution of functional, 2C-decorated vesicles provides a platform for further biochemical studies into this protein and its roles in enterovirus replication.

Ensuring effective monitoring of methotrexate (MTX) levels in the bloodstream of cancer patients undergoing high-dose methotrexate chemotherapy is crucial to prevent potentially harmful side effects. However, the absence of portable analytical devices suitable for point-of-care bedside monitoring has presented a significant obstacle to achieving real-time MTX monitoring. In this study, we developed an impedimetric immunosensor that doesn't require reagents for measuring MTX levels in undiluted human blood serum. This reagentless approach simplifies the assay process, enabling rapid and straightforward MTX quantification. The immunosensor transducer was fabricated by electrodepositing conductive network of porous multiwalled carbon nanotube@polypyrrole/polytyramine on screen-printed gold microchip electrode (SP–Au/MWCNT70@PPy-PTA). Polyclonal anti-MTX antibodies were immobilized on the film, acting as the immunorecognition element. Non-specific binding was prevented by blocking the transducer interface with denatured bovine serum albumin (dBSA) fibrils, resulting in SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA film electrode. When MTX binds to the SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA interface, the film conductance and electron transfer resistance changes. This conductivity attenuation allows for electrochemical impedimetric signal transduction without a redox-probe solution. The electrochemical impedance spectroscopy (EIS) results showed increased charge transfer resistance and phase angle as MTX concentrations increased. The SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA demonstrated high sensitivity, with a linear response from 0.02 to 20.0 μM and a detection limit of 1.93 nM. The detection limit was 50 times lower than the intended safe level of MTX in human serum. The immunosensor exhibited minimal cross-reactivity with endogenous MTX analogs and serum proteins. The SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA immunosensor presents a simple and rapid method for therapeutic drug monitoring compared to traditional immunoassay systems.

Bismuthene, a two-dimensional nanostructured material derived from the environmentally friendly and nontoxic element bismuth, holds significant potential for sustainable electrocatalytic applications. However, the large-scale application of bismuthene is hindered by the absence of a high-throughput method for synthesizing solution-processable bismuthene nanosheets, which are essential for the straightforward and low-cost fabrication of bismuthene-based nanostructure devices. This study introduces a simple solvothermal method for synthesizing bismuthene nanosheets, using hexamethylenetetramine (HMTA) as a structure-directing agent and in situ-generated hydrogen (H₂) from the alkaline hydrolysis of NaBH4 as the reducing agent. The structural and electron transfer properties were characterized by using microscopic, spectroscopic, and electrochemical analyses. To demonstrate the electrocatalytic application potential, a bismuthene-modified screen-printed carbon nanotube electrode was fabricated as a nanosensor for the quantitative detection of heavy metal ions in contaminated water. The nanosensor exhibited a wide linear concentration range and low detection limits of 0.1 and 0.16 ppb (μg/L) for Cd and Pb, respectively. Additionally, the sensor was integrated with a microfluidic flow cell, demonstrating its applicability for the flow-through analysis of Cd and Pb ions. The nanosensor showed high selectivity for Cd and Pb ions in the presence of other metal ions with excellent repeatability and sensor-to-sensor reproducibility, evidenced by a relative standard deviation of 2% and 10%, respectively.

A single run approach for rapid detection of nitrification inhibitor, dicyandiamide (DCD) using electrogenerated chlorine assisted polymerization through azo bond, under acidic conditions and at a preanodized screen printed carbon electrode (SPCE*) is presented. The role of chloride containing support electrolyte in acidic medium along with oxygen functionalities/edge sites are found to be crucial for the successful oxidative polymerization and subsequent adsorption of oxidized products on the electrode surface. The SEM, cyclic voltammetry and X-ray photoelectron spectroscopy studies were used to characterize the polymer film formation. The system exhibited a linear range between 20 and 170 μM with a detection limit of 3 μM (S/N = 3). The method was successfully tested for the detection of DCD in dairy and water samples. Simultaneous detection of DCD in the presence of melamine has also been demonstrated.

A new technique for sensing nanomolar concentrations of hydrazine in water samples is reported. A screen-printed carbon electrode (SPCE) altered using an amine-azo functional group encompassing poly(dicyandiamide) is used in this study. The modified electrode exhibits an enhanced activity toward hydrazine detection at a lower overpotential and broad linear scale between 20 nM and 1 mM, with an accurate sensitivity value of 0.1 nA μm–1 cm–2. To the best of our knowledge, poly(dicyandiamide)-modified electrodes exhibit one of the lowest limits of detection for any metal-free electrode that detects 6.7 nM (S/N = 3) of hydrazine. The method established sufficient selectivity and better recoveries. Finally, the poly(dicyandiamide)-modified SPCE* is highly suitable for electrochemical determination of hydrazine in water samples from tap and lake.

In this study, nanostructure kazakhstanite-like iron vanadate (FexV3xOy.H2O) was synthesized and calcined at different temperatures (100-800 °C) in a nitrogen atmosphere. The material was used to modify screen-printed carbon electrodes to achieve an electrocatalytic effect on the surface. The relationship between calcination conditions and the catalytic performance of the electrode towards the oxidation of chemotherapeutic drugs, including methotrexate (MTX) and folinic acid (FA), was studied. Various spectroscopic, microscopic, and electrochemical methods were used to characterize the synthesized materials. The results show that calcination induces changes in the electronic structure, nanostructure morphology, electroactive surface area, and electrocatalytic performance of the material. Screen-printed carbon electrode modified with FexV3xOy calcinated at 450 °C (SPC/FexV3xOy-450) was used to develop a voltammetric sensor for the determination of MTX and FA in blood serum. The response of the SPC/FexV3xOy-450 towards the electrooxidation of MTX and FA was the highest in comparison to the bare SPC and SPC/FexV3xOy calcined at other temperatures. The SPC/FexV3xOy-450 exhibited a linear relationship over a wide concentration range: 0.005-200 µM for MTX and 0.05-200 µM for FA. The detection limit was 2.85 nM for MTX and 7.79 nM for FA. Compared to conventional methods, the SPC/FexV3xOy-450 sensor had a short response time (5 min) for simultaneous detection of MTX and FA without signal interferences from coexisting electroactive compounds. The accurate and precise determination of MTX in the presence of FA confirmed the potential clinical applications of SPC/FexV3xOy-450 for therapeutic drug monitoring during chemotherapy.

A rapid, low-cost, and accurate point-of-care analytical device for the determination of prostate-specific antigen (PSA) is required for the early diagnosis and prognosis of prostate cancer (PCa). In this work, an electrochemical capacitive immunosensor was developed for the label-free detection of PSA. The immunosensor was based on the covalent immobilization of monoclonal anti-PSA antibody via carbodiimide chemistry onto gold electrode (AuE) pre-modified with a thin monolayer film of isophthalic acid (IPA). A methodology based on the steric hindrance of 1,3-substituted aryldiazonium salt was adopted to control the growth of the IPA thin film on the gold electrode. The non-specific binding sites were blocked with bovine serum albumin (BSA) to afford an AuE-IPA-anti-PSA-mAb|BSA immunosensor. The immunosensor was characterized by X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The analytical performance of the developed sensor was evaluated using the capacitance Nyquist plots generated from the complex impedance data. In addition, complex capacitance was also calculated from the imaginary part of the impedance and plotted against the log of frequency. The double layer capacitance from the circuit fitting (RSC) was also used and compared the sensitive capacitance signals to the changes in PSA concentrations. The LOD values were in fg.mL−1 and distinguishable from the blank (PBS) for the Nyquist plots of capacitance, complex capacitance, and double layer capacitance signals. The developed immunosensor exhibited good stability, selectivity, low detection limits, and a wide linear range which was suitable for screening of prostate cancer using prostate-specific antigen.

In this work, a low-cost, light-weight, highly efficient, and durable electrode in which NiFe-layered double hydroxide is electrodeposited on a carbon nanofiber (CNF) core supported on a carbon foam (CF) is introduced. The resulting 3D NiFe-CNFs-CF electrode shows excellent oxygen evolution reaction and hydrogen evolution reaction performance in alkaline media. When used as an anode and a cathode in the same cell, a current density of 10 mA cm−2 is achieved, at a cell voltage of 1.65 V. Moreover, good stability over a long testing time (50 h) is demonstrated. The ternary hybrid electrode gives rise to an excellent performance-to-weight ratio owing to its very low bulk density (≈34 mg cm−3) inherited from super lightweight components composed of CF and CNFs. The developed electrode can potentially be used in large-scale alkaline water electrolysis, in facilities such as offshore hydrogen production platforms, which can complement the variable renewable energy production of wind farms through hydrogen storage and fuel cells.

Surface modification is a hot topic in electrochemistry and material sciences because it affects the way materials are used. In this paper, a method for covalently attaching carboxyphenyl (PhCOOH) groups to a gold electrode is presented. These groups were grafted onto the electrode surface electrochemically via reduction of aryldiazonium salt. The resulting grafted surface was characterized using cyclic voltammetry (CV) before and after the functionalization procedure to validate the presence of the grafted layer. The grafting of PhCOOH groups was confirmed by analyzing electrode thickness and composition by ellipsometry and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) calculations indicated that the grafted layers provide a stable platform and resolved, for the first time, their interactions with oxygen.