Search

Timely and rapid detection of antibiotic residues in the environment is conducive to safeguarding human health and promoting an ecological virtuous cycle. A foldable paper-based photoelectrochemical (PEC) sensor was successfully developed for the detection of ampicillin (AMP) based on glutathione/zirconium dioxide hollow nanorods/aptamer (GSH@ZrO 2 HS@apt) modified cellulose paper as a reactive zone with laser direct-writing lead sulfide/cadmium sulfide/graphene (PbS/CdS/LIG) as photoelectrode and cobalt hydroxide (CoOOH) as a photoresist material. Initially, AMP was introduced into the paper-based reaction zone as a biogate aptamer, which specifically recognized the target and then left the ZrO 2 HS surface, releasing glutathione (GSH) encapsulated inside. Subsequently, the introduction of GSH into the reaction region and etching of CoOOH nanosheets to expose the PbS/CdS/LIG photosensitive material increased photocurrent. Under optimal conditions, the paper-based PEC biosensor showed a linear response to AMP in the range of 5.0 - 2 × 10 4 pM with a detection limit of 1.36 pM (S/N = 3). In addition, the constructed PEC sensing platform has excellent selectivity, high stability and favorable reproducibility, and can be used to assess AMP residue levels in various real water samples (milk, tap water, river water), indicating its promising application in environmental antibiotic detection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Fluoroquinolones (FQs) are widely used for their excellent antimicrobial properties, yet their release into aquatic environments pose risks to ecosystems and public health. The accurate monitoring and analysis of FQs present challenges due to their low concentrations and the complex matrices found in actual environmental samples. To address the need for auto-pretreatment and on-line instrumental analysis, developing new microextraction materials and protocols is crucial. Such advancements will provide better analytical assurance for the effective extraction and determination of FQs at trace levels, which is of great significance to environmental protection and human health., Results: In this work, we presented a Co 2+ mediated paper-based molecularly imprinted polymer chip (CMC@Co-MIP), combined with UPLC analysis, to develop an effective analytical method for identifying and quantifying trace amounts of ciprofloxacin (CIP) and enrofloxacin (ENR) in water samples. Notably, the addition of Co 2+ in CMC@Co-MIP helped to capture the template molecule CIP through coordination before imprinting, which significantly improved the ordering of the imprinted cavities. CMC@Co-MIP exhibited a maximum adsorption capacity up to 500.20 mg g -1 with an imprinting factor of 4.12, surpassing previous reports by a significant margin. Furthermore, the enrichment mechanism was extensively analyzed by various characterization techniques. The developed method showed excellent repeatability and reproducibility (RSD < 13.0 %) with detection limits ranging from 0.15 to 0.21 μg L -1 and recoveries ranging from 64.9 % to 102.3 % in real spiked water samples., Significance: We developed a novel microextraction paper-based chip based on Co 2+ mediation, which effectively improved the selectivity and convenience of extracting FQs. This breakthrough allowed the chip to have a high enrichment efficiency as well as provide a robust on-line instrumental program. It also confirms that the imprinting scheme based on metal ion coordination is a high-performance strategy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Efficient monitoring of glucose concentration in the human body necessitates the utilization of electrochemically active sensing materials in nonenzymatic glucose sensors. However, prevailing limitations such as intricate fabrication processes, lower sensitivity, and instability impede their practical application. Herein, ternary Cu-Co-Ni-S sulfides nanoporous network structure was synthesized on carbon fiber paper (CP) by an ultrafast, facile, and controllable technique through on-step cyclic voltammetry, serving as a superior self-supporting catalytic electrode for the high-performance glucose sensor., Results: The direct growth of free-standing Cu-Co-Ni-S on the interconnected three-dimensional (3D) network of CP boosted the active site of the composites, improved ion diffusion kinetics, and significantly promoted the electron transfer rate. The multiple oxidation states and synergistic effects among Co, Ni, Cu, and S further promoted glucose electrooxidation. The well-architected Cu-Co-Ni-S/CP presented exceptional electrocatalytic properties for glucose with satisfied linearity of a broad range from 0.3 to 16,000 μM and high sensitivity of 6829 μA mM - 1 cm - 2 . Furthermore, the novel sensor demonstrated excellent selectivity and storage stability, which could successfully evaluate the glucose levels in human serum. Notably, the novel Cu-Co-Ni-S/CP showed favorable biocompatibility, proving its potential for in vivo glucose monitoring., Conclusion: The proposed 3D hierarchical morphology self-supported electrode sensor, which demonstrates appealing analysis behavior for glucose electrooxidation, holds great promise for the next generation of high-performance glucose sensors., (© 2024. The Author(s).)

In this work, a new chemiluminescence (CL) system of Co-Fe prussian blue analogs nanocubes (Co-Fe PBA NCs) that can catalyze luminol to produce strong CL in the absence of H 2 O 2 was established. Co-Fe PBA NCs have the property of oxidase-like activity, and it can catalyze the generation of active oxygen radicals in a dissolved oxygen system. Since caffeic acid (CA) can remove reactive oxygen species in the system, a sensitive detection method for CA on a paper-based chip was developed. Under the optimal conditions, this method showed a good linear response to CA in the range of 10 - 800 ng mL -1 with a limit of 3 ng mL -1 . The proposed method had been used for the determination of CA in tea samples. The results may open a new avenue for the catalytic property on luminol CL system without extra oxidants.

A facile approach utilizing synthesis of cobalt nanoparticles in green polymers of chitosan (CS) coating layer on high surface area cellulose microfibers of filter paper (CFP) is described for the catalytic reduction of nitrophenol and an organic dye using NaBH 4 . Simple steps of CFP coating with 1wt% CS aqueous solution followed by Co 2+ ions adsorption from 0.2M CoCl 2 aqueous solution were carried out to prepare pre-catalytic strips. The Co 2+ loaded pre-catalytic strips of CS-CFP were treated with 0.19M NaBH 4 aqueous solution to convert the ions into nanoparticles. Successful Co nanoparticles formation was assessed by various characterization techniques of FESEM, EDX and XRD analyzes. TGA analyses were carried out on CFP, CS-CFP, and Co-CS-CFP for the determination of the amount of Co particles formed on the CS-FP, and to track their thermal properties. Furthermore, we demonstrated that the Co-CS-CFP showed an excellent catalytic activity and reusability in the reduction reactions a nitroaromatic compound of 2,6-dintirophenol (2,6-DNP) and brilliant cresyl blue (BCB) dye by NaBH 4 . The Co-CS-CFP catalyzed the reduction reactions of 2,6-DNP and BCB by NaBH 4 with psuedo-first order rate constants of 0.0451 and 0.1987min -1 , respectively., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Developing cost-effective and stable materials for the electrocatalysis of hydrogen evolution reaction (HER) remains challenging. In this study, efficient catalysts for HER were synthesized by integrating the cobalt and molybdenum oxides via electrodeposition, followed by subsequent sulfurization of the as-prepared oxides using chemical vapor deposition (CVD). This methodology allowed the incorporation of both cobalt and molybdenum components into the catalyst in a single step. The as-synthesized CoSx@MoSx/MoOx-based catalysts exhibited excellent hydrogen production performance in acidic media owing to the presence of Co-S and Mo-S bonds in the hybrid structure. Particularly, CoSx@MoSx/MoOx(90@360) and MoSx@CoOx(180@180) displayed the best HER performances with low overpotentials of 80 mV and 150 mV, respectively. The catalysts were highly stable, with their stability preserved for over 1000 cycles with marginal reduction in overall efficiency. Therefore, these findings suggest the potential of CoSx@MoSx/MoOx and MoSx@CoOx composites as ideal candidates for developing low-cost catalysts for electrochemical hydrogen production. [ABSTRACT FROM AUTHOR]

A new chemosensor 1 was synthesized by reacting rhodamine B hydrazide and 2,3,4-trihydroxybenzaldehyde, which was then characterized by spectroscopic techniques and single crystal X-ray crystallography. Sensor 1 has the ability to sense Co 2+ /Cu 2+ ions by "naked-eye" with an apparent colour change from colourless to pink in different solvent system, MeCN and DMF respectively. Furthermore, it can selectively detect Co 2+ /Cu 2+ among wide range of different metal ions, and it exhibits low detection limit of 4.425 × 10 -8 M and 1.398 × 10 -7 M respectively. Binding mode of the two complexes were determined to be 1:1 stoichiometry for Co 2+ complex and 1:2 stoichiometry for Cu 2+ complex through Job's plot, IR spectroscopy, mass spectrometry and 1 H NMR spectroscopy. Moreover, reversibility of the sensor 1 as copper (II) ion detector was determined by using EDTA and the results showed that sensor 1 can be reused for at least 6 cycles. Other than that, a low cost chemosensor test strips were fabricated for the convenient "naked-eye" detection of Co 2+ and Cu 2+ in pure aqueous media. The MTT assay was conducted in order to determine the cytotoxicity of sensor 1 towards human cell lines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The cellulose fibers that form washi are longer than those of regular paper made from wood pulp. Hence, the mechanical properties of washi can be higher than those of conventional paper. This study evaluated the magnetic, magnetostrictive, and tensile properties of negative magnetostrictive cobalt ferrite (CoFe2O4) particle dispersed handmade washi (washi−CoFe2O4). The CoFe2O4 additives magnetized the washi, which displayed negative magnetostriction with the fiber direction perpendicular to the magnetic field and in the parallel fiber direction. Concerning the mechanical properties, the washi−CoFe2O4 displayed an elongation of up to 77% after yielding. [ABSTRACT FROM AUTHOR]

Remediation of engineered-nanomaterials is an up-coming major environmental concern. This study demonstrates adsorptive-remediation of cobalt oxide nanoparticles (CoO NPs) from the water. The α-cellulose-fibers were extracted from waste-paper biomass (WP-αCFs) and magnetized with Fe 3 O 4 NPs (M-WP-αCFs). The XRD, FT-IR, and TGA were performed for detailed characterization of the newly developed bioadsorbent. The M-WP-αCFs was then applied for adsorptive remediation of CoO NPs. The adsorptive kinetics of CoO NPs adsorption onto the M-WP-αCFs reveals the pseudo-second-order model. The various adsorption isotherm studies revealed Langmuir is a best-fit isotherm. A prominently high adsorption capacity q m (1567 mg/g) corroborated extraordinary adsorptive potential of M-WP-αCFs. Furthermore, CoO NPs were adsorbed onto M-WP-αCFs were analyzed by the XPS, VSM, and TEM. Therefore, this study gave rise WP biomass extracted and rapidly-separable nano-biocomposite of 'M-WP-αCFs' with a high-capacity for CoO NPs remediation and can be further applied in remediation of several other engineered-nanomaterials., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We present a high-capacity pseudocapacitor based on a hierarchical network architecture consisting of Co(3)O(4) nanowire network (nanonet) coated on a carbon fiber paper. With this tailored architecture, the electrode shows ideal capacitive behavior (rectangular shape of cyclic voltammograms) and large specific capacitance (1124 F/g) at high charge/discharge rate (25.34 A/g), still retaining ~94% of the capacitance at a much lower rate of 0.25 A/g. The much-improved capacity, rate capability, and cycling stability may be attributed to the unique hierarchical network structures, which improves electron/ion transport, enhances the kinetics of redox reactions, and facilitates facile stress relaxation during cycling., (© 2011 American Chemical Society)

The electrochemical oxidation of pulp and paper making wastewater assisted by transition metal (Co, Cu) modified kaolin in a 200 ml electrolytic batch reactor with graphite plate as electrodes was investigated. H(2)O(2), which produced on the surface of porous graphite cathode, would react with the catalysts to form strong oxidant (hydroxyl radicals) that can in turn destroy the pollutants adsorbed on the surface of kaolin. The transition metal (Co, Cu) modified kaolin was also characterized by XRD and SEM before and after the modification and the results showed that the transition metals were completely supported on kaolin and formed a porous structure with big BET surface. The mechanism was proposed on the basis of XPS analysis of the catalyst after the degradation process. Series of experiments were also done to prove the synergetic effect of the combined oxidation system and to find out the optimal operating parameters such as initial pH, current density and amount of catalyst. From the results it can be founded that when the initial pH was at 3, current density was 30 mA cm(-2); catalyst dose was 30 g dm(-3), COD (chemical oxygen demand) removal could reach up to 96.8% in 73 min.

A paper ionophoretic method is described for the study of equilibria in mixed ligand (nitrilotriacetate-cysteine) complex system in solution. The proportion of ionic species of nitrilotriacetate (NTA) and cysteine were varied by changing the pH of background electrolyte. The stability constants of Cu(II)-NTA-cysteine and Co(II)-NTA-cysteine complexes were found to be 6.35+/-0.05 and 5.45+/-0.02 (logarithm stability constant values), respectively, at ionic strength 0.1 M and a temperature of 35 degrees C.

In this work, we designed a novel Schiff-base probe from the condensation reaction of 3,5-diiodosalicylaldehyde with isoniazid. Treatment of the sensor molecule with different metal ions like K + , Ba 2+ , Ca 2+ , Mg 2+ , Fe 2+ , Mn 2+ , Co 2+ , Cu 2+ , Cd 2+ , Ni 2+ , Hg 2+ , Zn 2+ , Pb 2+ and Al 3+ in visual inspection and absorption measurements explained its colorimetric sensing ability. The sensor DISN displays a remarkable color variation from pale yellow to brownish-orange towards Co 2+ ion. The absorption and emission spectra of DISN, upon treating with various anions including F - , Br - , Cl - , I - , HSO 4 - , NO 3 - , H 2 PO 4 - , and CN - were tested. The addition of the fluoride ion to the receptor caused not only the intense color variation from pale yellow to orange but also a significant fluorescence turn-on response. Job's plot method fixed the binding of Co 2+ and F - to DISN separately, in 2:1 and 1:1 binding stoichiometry, respectively. The detection limit of 1.24 × 10 -7  M and 0.108 × 10 -6  M was attained for Co 2+ ions with DISN. Furthermore, DISN displays its practical applicability in filter-paper strips, live cell imaging, and real sample analyses.- , respectively. The TD-DFT calculations further supported the photophysical properties involved in the free probe and its complexes. The YES and INHIBIT logic function was found to operate from modulation in the absorbance and fluorescence behavior of Co 2+ and F - ions with DISN. Furthermore, DISN displays its practical applicability in filter-paper strips, live cell imaging, and real sample analyses., (Copyright © 2019. Published by Elsevier B.V.)

A ternary hierarchical hybrid Ni@Co x S y /poly(3,4-ethylenedioxythiophene)-reduced graphene oxide (Ni@Co x S y /PEDOT-rGO) is rationally designed and in situ facilely synthesized as electrocatalyst to construct a binder-free sensing platform for non-enzymatic glucose monitoring through traditional electrodeposition procedure. The as-prepared Ni@Co x S y /PEDOT-rGO presents unique hierarchical structure and multiple valence states as well as strong and robust adhesion between Ni@Co x S y /PEDOT-rGO and GCE. Profiting from the aforementioned merits, the sensing platform constructed under optimal conditions achieved a wide detection range (0.2 μM ~ 2.0 mM) with high sensitivity (1546.32 μA cm -2  mM -1 ), a rapid response time (5 s), an ultralow detection limit (0.094 μM), superior anti-interference performance, excellent reproducibility and considerable stability. Furthermore, the sensor demonstrates an acceptable accuracy and appreciable recoveries ranging from 90.0 to 102.0% with less than 3.98% RSD in human blood serum samples, indicating the prospect of the sensor for the real samples analysis. It will provide a strategy to rationally design and fabricate ternary hierarchical hybrid as nanozyme for glucose assay., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

This study optimizes a novel surfactant-assisted green liquor dregs (GLD) pretreatment of paper mill sludge (PMS), both of which are wastes from the kraft pulping industry, using a combined Response Surface Methodology (RSM) design. Optimized conditions give a maximal reducing sugar release of 16.38 g/L. A substantial reduction in heavy metals aluminum, chromium, cobalt, arsenic, lead, and copper after pretreatment illustrates the enhancement of substrate digestibility by reducing toxic elements. Separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) for hydrogen production are assessed. SSF produced a hydrogen yield of 3.72 mL/g, displaying a 36.26% increase from pretreated PMS compared to SHF. These findings provide insights into possible methods of reducing process duration, energy input, and costs incurred with waste disposal within the paper industry. Furthermore, improved hydrogen yield using an SSF process demonstrates the potential beneficiation of pulp and paper GLD and PMS wastes. • A novel surfactant-assisted GLD pretreatment of PMS developed. • An optimal reducing sugar release of 16.38 g/L was obtained. • Novel pretreatment protocol achieved significant heavy metal reduction. • SSF hydrogen production from pretreated PMS increased hydrogen yield by 36.26%. [ABSTRACT FROM AUTHOR]

A fluorometric assay was constructed for supersensitive determination of Cu 2+ and Co 2+ based on their quenching effect on the orange fluorescence of methionine-capped gold nanoclusters (Met-AuNCs). A simple one-step method was developed for the preparation of the Met-AuNCs, employing L-methionine as both a reducing and protecting reagent. Within 10 min, water soluble Met-AuNCs were obtained with an average size of 2.4 nm. Under photoexcitation at 370 nm, the Met-AuNCs possess a maximum emission at 580 nm and a quantum yield of 2.3%. The response is fast (1 min), and the selectivity for Cu 2+ and Co 2+ is high over other metal ions. The detection limits for Cu 2+ and Co 2+ are around 47 and 420 pM, respectively. The effects were used to design a test paper for visual detection of Cu 2+ and Co 2+ . Using this test paper, 1 μM of Cu 2+ /Co 2+ can be detect under the UV lamp (365 nm excitation). It is perceived to be a promising tool for the rapid on-site determination of Cu 2+ and Co 2+ in real water samples. Graphical abstract Schematic presentation of gold nanoclusters (AuNCs) synthesis with methionine as both reducing and protecting reagent, Cu 2+ /Co 2+ detection based on the quenching of the fluorescence of AuNCs, and visual detection of Cu 2+ /Co 2+ based on a respective test strip.

The development of low‐cost and efficient electrolyzer components is crucial for practical electrochemical carbon dioxide reduction (ECR). In this study, facile non‐woven cellulose‐based porous transport layers (PTLs) were developed for high current density CO2‐to‐CO conversion. By depositing a cobalt phthalocyanine (CoPc) catalyst‐layer over the PTLs, we fabricated ECR‐functioning gas‐diffusion‐electrodes (GDEs) for both flow‐cell and zero‐gap electrolyzers. Under optimal conditions, the Faradaic efficiency of CO (FECO) reached 92 % at a high current density of 200 mA cm−2. Furthering the architecture of the GDEs, CoPc was incorporated into the initial PTL slurry, forming ECR‐active PTLs without the need for an additional catalyst‐layer. The new GDE‐architecture favored the CoPc‐distribution by enhancing the contact and interactions with the carbon substrate and demonstrated a stable electrolysis process for over 50 h in a zero‐gap cell at 200 mA cm−2 with a FECO of 80 %. [ABSTRACT FROM AUTHOR]

The study encompasses an investigation of optical, photothermal and biocompatibility properties of a composite consisting of golden cores surrounded by superparamagnetic CoFe 2 O 4 nanoparticles. Accompanied with the experiment, the computational modeling reveals that each adjusted magnetic nanoparticle redshifts the plasmon resonance frequency in gold and nonlinearly increases the extinction cross-section at ~800 nm. The concentration dependent photothermal study demonstrates a temperature increase of 8.2 K and the photothermal conversion efficiency of 51% for the 100 μg/mL aqueous solution of the composite nanoparticles, when subjected to a laser power of 0.5 W at 815 nm. During an in vitro photothermal therapy, a portion of the composite nanoparticles, initially seeded at this concentration, remained associated with the cells after washing. These retained nanoparticles effectively heated the cell culture medium, resulting in a 22% reduction in cell viability after 15 min of the treatment. The composite features a potential in multimodal magneto-plasmonic therapies., (© 2024 Wiley‐VCH GmbH.)

• The carbon paper as the substrate was used to synthesize CEs in DSSC for the first time. • The CoP 3 /CP electrode exhibited low charge transfer resistance. • The DSSC with CoP 3 /CP electrode achieved the photoelectric conversion efficiency of 6.84%. The cobalt triphosphide (CoP 3) was grew on carbon paper (CP) by using a hydrothermal method and served as counter electrode (CE) catalyst in dye-sensitized solar cells (DSSCs). The morphology of the CoP 3 /CP CE exhibits a regular fibrous structure, which provides a guarantee for its good electrochemical performance of the CE made from the cyclic voltammetry, Tafel test, etc. Various photoelectric performance tests also show that the DSSCs with CoP 3 /CP CE achieves good photoelectric conversion efficiency of 6.84% under 100 mW·cm−2 illumination, which can compare to that of the DSSC assembled with the Pt (6.79%) CE. Metal phosphides are rarely used as CEs in DSSCs, and they will have a good promising alternative to the Pt electrode in the future. [ABSTRACT FROM AUTHOR]

A simple sol-gel combustion process was employed for the creation of MFe 2 O 4 (M=Ni, Co) nanoparticles. The synthesized nanoparticles, acting as both photocatalysts and gas sensors, were analyzed using various analytical techniques. MFe 2 O 4 (M=Ni, Co) material improved the degradation of methylene blue (MB) under UV-light irradiation, serving as an enhanced electron transport medium. UV-vis studies demonstrated that NiFe 2 O 4 achieved a 60% degradation, while CoFe 2 O 4 nanostructure exhibited a 76% degradation efficacy in the MB dye removal process. Furthermore, MFe 2 O 4 (M=Ni, Co) demonstrated chemosensitive-type sensor capabilities at ambient temperature. The sensor response and recovery times for CoFe 2 O 4 at a concentration of 100 ppm were 15 and 20, respectively. Overall, the synthesis of MFe 2 O 4 (M=Ni, Co) holds the potential to significantly improve the photocatalytic and gas sensing properties, particularly enhancing the performance of CoFe 2 O 4 . The observed enhancements make honey MFe 2 O 4 (M=Ni, Co) a preferable choice for environmental remediation applications., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The development of an ultrasensitive and precise measurement of a breast cancer biomarker (cancer antigen 15-3; CA15-3) in complex human serum is essential for the early diagnosis of cancer in groups of healthy populations and the treatment of patients. However, currently available testing technologies suffer from insufficient sensitivity toward CA15-3, which severely limits early large-scale screening of breast cancer patients. We report a versatile electrochemical immunoassay method based on atomically cobalt-dispersed nitrogen-doped carbon (Co-NC)-modified disposable screen-printed carbon electrode (SPCE) with alkaline phosphatase (ALP) and its metabolite, ascorbic acid 2-phosphate (AAP), as the electrochemical labeling and redox signaling unit for sensitive detection of low-abundance CA15-3. During electrochemical detection by differential pulse voltammetry (DPV), it was found that the Co-NC-SPCE electrode did not have a current signal response to the AAP substrate; however, it had an extremely favorable response current to ascorbic acid (AA). Based on the above principle, the target CA15-3-triggered immunoassay enriched ALP-catalyzed AAP produces a large amount of AA, resulting in a significant change in the system current signal, thereby realizing the highly sensitive detection of CA15-3. Under the optimal AAP substrate concentration and ALP catalysis time, the Co-NC-SPCE-based electrochemical immunoassay demonstrated a good DPV current for CA15-3 in the assay interval of 1.0 mU/mL to 10,000 mU/mL, with a calculated limit of detection of 0.38 mU/mL. Since Co-NC-SPCE has an excellent DPV current response to AA and employs split-type scheme, the constructed electrochemical immunoassay has the merits of high preciseness and anti-interference, and its clinical diagnostic results are comparable to those of commercial kits., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The aim of this study is to build and test an amperometric biosensor to determine oxidized glutathione (GSSG). The biosensor is based on glutathione reductase (GR), which was immobilized onto the surface of reduced graphene oxide (rGO) modified with cobalt sulfide (CoS2). CoS2 nanostructures on the composite paper surface are active centers for immobilizing the GR enzyme. The conversion of GSSG into reduced glutathione was monitored with voltammetry in the presence of nicotinamide adenine dinucleotide phosphate reduced form (NADPH) on the GR‐CoS2/rGO immobilized electrode surface. The biosensor's cyclic volt response is linearly correlated with GSSG concentrations of 0.01–500 μM in a 0.1 M pH 7.4 phosphate‐buffer solution (PBS). The performance of the sensor was high, with a detection limit of 0.48 μM and a sensitivity of 0.6 mA μM cm−2. Four human blood samples were tested for GSSG with both the biosensor and Ellman's assay, which showed nearly identical results, confirming the biosensor's reliability. [ABSTRACT FROM AUTHOR]

Point-of-care (POC) diagnostic devices play significant roles in delivering vital surveillance information and providing proper and timely care to patients. There is a challenge in the development of new diagnostic tools to overcome their current shortcomings in terms of cost issues, accuracy and performance. Herein, a highly efficient paper-based analytical device based on a 2D metal-organic framework (MOF) has been reported for the colorimetric/fluorometric monitoring of glucose. Because of the inherent bifunctional activity of cobalt-terephthalate MOF (CoMOF) nanosheets, great improvements were made to the stability and performance of glucose oxidase (GOX) and to its catalytic effect on the reaction of o-phenylenediamine (OPD) and H 2 O 2. The exceptional behavior of 2D CoMOF, along with a precise smartphone readout, led to the rapid and sensitive colorimetric/fluorometric detection of glucose in biological samples. Paper modified by CoMOF and GOX was stable for a long time, and a yellow-brown color and a high fluorescence emission were observed after the addition of a low volume of sample and OPD solutions. The probe showed a wide linear effectiveness range of 50 μM-15 mM, with colorimetric and fluorometric detection limits of 16.3 and 3.2 μM, respectively. Despite its great simplicity, the developed probe showed high performance and accuracy for the quantification of glucose. Image 1 • Exceptional bifunctional activity of 2D cobalt metal-organic framework (CoMOF). • Notable enhancement of the stability and performance of GOX on the paper by CoMOF. • Superb catalyzing effect of CoMOF on the dissociation of H 2 O 2 to hydroxyl radicals. • Development of paper-based diagnostic assay for glucose monitoring in blood. • Recording of colorimetric/fluorometric signals by smartphone readout. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries appear to be one of the most promising energy-storage devices owing to the unparalleled theoretical specific energy, relatively inexpensive price and abundant resources. Despite these attractive features, the practical performances of sulfur cathode still remain a lot of challenges, such as the electrical insulating nature of S and Li 2 S, huge volume change during cycling, notorious shuttle effect of lithium polysulfide intermediates (LiPSs), sluggish redox kinetics and construction of thick electrodes with high sulfur loading. Here, CoFe 2 O 4 nanoparticles anchored on the carbon nanotube (CNT) paper is proposed as free-standing sulfur host to address the issues. The cross-linking CNT network can serve as conductive matrix and accommodate volume change upon cycling simultaneously. Meanwhile, the CoFe 2 O 4 nanoparticles are capable of effectively anchoring LiPSs to suppress the shuttle effect and accelerating LiPSs conversion to boost redox kinetics. Moreover, the free-standing paper electrode without any binder is conducive to constructing stable cathode with high sulfur loading. In consequence, the well-designed S/CoFe 2 O 4 /CNT paper cathodes deliver impressive electrochemical performance, demonstrating an initial discharge capacity of 755.3 mAh g−1 and remaining a high reversible capacity of 642.6 mAh g−1 after 400 cycles at 2 C with an inconspicuous decay of 0.04% per cycle. The bimetallic oxide CoFe 2 O 4 nanoparticles anchored on the carbon nanotube paper is proposed as free-standing sulfur host with enhanced polysulfide trapping and catalytic effects for advanced Li-S batteries. [Display omitted] • Binder-free host realizes high sulfur loading and energy density for Li-S battery. • CoFe 2 O 4 /CNT paper inhibits the polysulfide shuttling via strong chemical interaction. • CNT-anchored CoFe 2 O 4 catalytically promotes the polysulfide conversion kinetics. • The Li-S battery with S/CoFe 2 O 4 /CNT cathode exhibits enhanced capacity and stability. [ABSTRACT FROM AUTHOR]

Cobalt(II) phthalocyanine (CoPc) was suspended in aqueous medium and the colloidal system was used as catalyst for the electrochemical determination of hydrogen peroxide on paper-based electrodes modified with carbon nanomaterials. H2O2 was oxidised at 0.275 V vs. Ag pseudoreference electrode. This system was adapted to develop a glucose sensor with glucose oxidase immobilized on the cellulose electrode. CoPc suspended nanoparticles acted as nanoenzyme mimicking peroxidase activity and were combined with different carbon nanomaterials to form hybrids with optimised catalytic performance. GO-CoPc paper-based electrodes yielded the best results with a linear range of ∼12 μM to 49 mM for H2O2 and 0.1 mM to 1 mM for glucose. Glucose was determined in physiological serum and juice samples with recoveries of 93.3 and 94.2% respectively. CoPc could replace HRP for the catalytic sensing of H2O2, without the need to be dissolved. This material can be used in situ in a simple protocol with other nanomaterials for electrode modification. The sensor described has the advantage of easy preparation, using the catalyst in colloidal form, long term stability, and versatility to be adapted to other low cost and disposable enzymatic systems. [ABSTRACT FROM AUTHOR]