Search

Excessive copper (Cu2+) causes adverse effects on human health and the ecological environment. Traditional methods for detecting Cu2+ have drawbacks such as high detection costs, complex operating conditions, and being time consuming. Therefore, there is an urgent need to develop simple detection methods to better meet specific health and environment quality needs. In this work, a paper-based fluorescence sensor was prepared (herein referred to as the as-prepared method) by immersing filter paper in aqueous polyethyleneimine (PEI) solution, and its potential use in Cu2+ detection was investigated. The results showed that the as-prepared paper samples, with fluorescence properties obtained by aggregation-induced luminescence of PEI, have selective recognition of Cu2+ based on the internal filtration effect, and the lowest detection limit is 0.03 μM. In addition, the relative error of this method is in the range of 1.80~2.23%, which is relatively comparable to the national standard method (0.63~630 μM), demonstrating high accuracy. Therefore, paper-based sensors with a simple preparation method have potential applications in the detection of Cu2+ in water. [ABSTRACT FROM AUTHOR]

In the realm of electrochemical nitrite detection, the potent oxidizing nature of nitrite typically necessitates operation at high detection potentials. However, this study introduces a novel approach to address this challenge by developing a highly sensitive electrochemical sensor with a low reduction detection potential. Specifically, a copper metal nanosheet/carbon paper sensitive electrode (Cu/CP) was fabricated using a one-step electrodeposition method, leveraging the catalytic reduction properties of copper's high occupancy d-orbital. The Cu/CP sensor exhibited remarkable performance in nitrite detection, featuring a low detection potential of −0.05 V vs. Hg/HgO, a wide linear range of 10~1000 μM, an impressive detection limit of 0.079 μM (S/N = 3), and a high sensitivity of 2140 μA mM−1cm−2. These findings underscore the efficacy of electrochemical nitrite detection through catalytic reduction as a means to reduce the operational voltage of the sensor. By showcasing the successful implementation of this strategy, this work sets a valuable precedent for the advancement of electrochemical low-potential nitrite detection methodologies. [ABSTRACT FROM AUTHOR]

As water effluents are often highly contaminated with metals, having a quick and cost-effective method of analysis is crucial. This study used the supernatant derived from the green synthesis of silver nanoparticles (AgNPs) with Solanum mammosum to detect mercury, copper, and iron with a low-cost cellulose paper-based sensor and a rapid colorimetric method applying ultraviolet–visible spectroscopy (UV–Vis). AgNPs in two precursor concentrations using silver nitrate, 1 mM (17.4 ± 9 nm) and 50 mM (and 22 ± 8.1 nm), were utilized to assess the efficacy of the analysis and removal of Hg2+, Cu2+, and Fe3+ from contaminated water. Cellulose paper-based sensor showed limits of detection (LODs) for Hg2+ of 2.46 and 123 μM using AgNPs at concentrations of 1 and 50 mM, respectively. For Cu2+, the LODs were 55 and 2750 μM, and for Fe3+, the LODs were 49 and 2470 μM using the respective concentrations. To differentiate and detect the cations with the naked eye, a potassium iodide and potassium ferrocyanide (1:1) aqueous solution was used, producing a yellow, pink, and blue color for Hg2+, Cu2+, and Fe3+, respectively. Additionally, the titration curves of Hg2+, Fe3+, and Cu2+ were examined by UV–Vis using the supernatant liquid. The LODs for the UV–Vis method using AgNPs at a concentration of 1 mM were 1.50 μM for Hg2+, 10.7 μM for Cu2+, and 4.33 μM for Fe3+, while the LODs for AgNPs at 50 mM were 5.75, 27.6, and 15 μM for Hg2+, Cu2+, and Fe3+, respectively. Furthermore, these nanoparticles were utilized to assess the efficacy of the removal of Hg2+, Cu2+, and Fe3+ from contaminated water. Removal efficiency with the solid 50 mM AgNPs was analyzed via flame absorption spectrophotometry; values over 95% were obtained for the three ions. The results underscore the effectiveness of a green synthesis approach to generating AgNPs, enabling efficient and economical cation analysis and water decontamination.

This work focuses on a systematic method to produce Ag, Cu, and Ag/Cu metallic nanoparticles (MNPs) in situ assisted with ultrasound on cellulose paper. By tuning the concentration of AgNO3 and CuSO4 salt precursors and ultrasound time, combined with a fixed concentration of ascorbic acid (AA) as a reducing agent, it was possible to control the size, morphology, and polydispersity of the resulting MNPs on cellulose papers. Notably, high yield and low polydispersity of MNPs and bimetallic nanoparticles are achieved by increasing the sonication time on paper samples pre-treated with salt precursors before reduction with AA. Moreover, mechanical analysis on paper samples presenting well-dispersed and distributed MNPs showed slightly decreasing values of Young's modulus compared to neat papers. The strain at break is substantially improved in papers containing solely Ag or Cu MNPs. The latter suggests that the elastic/plastic transition and deformation of papers are tuned by cellulose and MNPs interfacial interaction, as indicated by mechanical analysis. The proposed method provides insights into each factor affecting the sonochemistry in situ synthesis of MNPs on cellulose papers. In addition, it offers a straightforward alternative to scale up the production of MNPs on paper, ensuring an eco-friendly method.

Trace elements have a significant effect on biochemical reactions and therefore the presence of optimum levels of trace elements is essential for bioreactor performances. In this study, the effects of five trace elements on biomethane production have been investigated. Experimental studies have been carried out with multiple batch reactors at 15 day HRT and mesophilic temperatures. The optimum concentrations for each of the trace elements Fe, Cu, Ni, Co and Mg were found as 5, 0.5, 0.5, 0.5 and 100 mg/L, respectively. Among tested trace elements, Cu was the one which provided the highest biomethane production. Cu addition was resulted in a 46 % increase in biomethane production followed by Co with 24 %. The biomethane production rate for these two trace elements was 191.70 and 110.77 ml CH4/g COD, respectively. Optimum levels for Ni, Fe and Mg increased biomethane production rate by approximately 14.3, 10 and 17 % compared to control groups, respectively. Because the exact amount of trace element requirement for each industry/reactor is different, specific case studies should be performed for each application. These results could be used as initial trace element concentrations for further continuous studies. [ABSTRACT FROM AUTHOR]

In the current strategy, a highly sensitive and fast one-step colorimetric assay for trace determination of Cu2+ in water is presented. The planned assay was based upon the use of varnish polish-modified filter paper printed with 2-[5-(2-hydroxy-5-sulfophenyl)-3-phenyl-1-formazyl] benzoic acid monosodium salt, commercially named zincon. Under optimal conditions, the designed assay readily recognised the formation of blue–purple-coloured Cu–ZI chelate in less than 10 min. The proposed probe was able to detect Cu2+ in the concentration range from 0.04 to 10 μg/mL (6.34 × 10−1 to 1.59 × 103µM), with low limit of detection (LOD) of 0.01 μg/mL (1.59 × 10−1 µM). The LOD was 10-fold lower than the allowable level for Cu2+ in drinking water set by WHO legislation. The assay was applied for Cu2+determination in water with acceptable recoveries (89.6–102.1%) and precision (<3%). Therefore, the proposed sensing assay might be considered as a potential rapid and low-cost candidate for total determination and speciation of Cu2+in water samples. [ABSTRACT FROM AUTHOR]

We report a series of structurally relevant copper phenanthroline complexes as pre-catalysts for highly selective electrocatalytic reduction of CO2 to C2 products using inexpensive carbon paper electrodes. The Cu complexes with non-substituted phenanthroline promote the production of ethylene with a high faradaic efficiency of 71.2%, while the one with pyridinium-functionalized ligands is more selective for ethanol. The C2 selectivity can be effectively tuned by increasing the number of coordinated phenanthrolines and remains high at a wide range of potentials. [ABSTRACT FROM AUTHOR]

Lithium is perceived as an ideal anode for next generation batteries with high‐energy density. However, the critical issue of the intractable growth of Li dendrites, which leads to a poor cycling life, still remains. Herein, a hierarchical surface is designed and constructed on carbon fiber (CF) using binders in fabricated CF paper (CFP). The lightweight CF with high mechanical properties is facilitated to establish a 3D network structure as an alternative to Cu foil. The binders are transformed into oxygen‐containing amorphous carbon and sodium carbonate (Na2CO3) using a low‐temperature carbonization process, leading to uniform Li nucleation and a stable solid electrolyte interphase layer with inorganic components. In the electrochemical test, the CFP with amorphous carbon and Na2CO3 (ANCFP) shows a low Li nucleation overpotential and smooth dendrite‐free Li plating. Furthermore, the ANCFP electrode exhibits good cycling stability in half and symmetrical cells. A full‐cell assembled using a LiFePO4 cathode with high loading (≈13 mg cm−2) achieves a high‐energy density of 428 Wh kg−1 (at 0.1 C) and an excellent capacity retention of 85% at 1 C after 300 cycles. This strategy is expected to help realize highly stable Li metal anodes for practical application by suppressing Li dendrite growth. [ABSTRACT FROM AUTHOR]

Copyright of Chemija is the property of Lithuanian Academy of Sciences Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three grades of pectin xanthates (PX1, PX2, and PX3) have been prepared by the reaction of pectin with carbon disulfide (CS2) in an alkaline medium using NaOH, via the xanthation process. The percentage yield of prepared pectin xanthates has been found to be 87.06%, 90.38%, and 93.80% for PX1, PX2, and PX3, respectively. Prepared pectin xanthates and raw pectin were utilized for heavy metals (Cu(II) and Ni(II)) and lignin enriched paper industry wastewater (LEPIW) treatment. The removal percentage of pectin, PX1, P X2, and PX3 for Cu removal at optimum condition (adsorbent dose: 5.14 g/L, pH: 5 for Cu and 7 for Ni, optimum temperature: 50°C and time: 80 min for Cu(II) and 100 min for Ni(II)) has been found as 85%, 92.33%, 93.5%, and 94.66% and 76.66%, 89.44%, 91.66%, and 93.33%, respectively, for Ni removal. The LEPIW treatment efficacy for pectin, PX1, PX2, and PX3 has been found to be 54%, 77%, 83%, and 86% for the initial COD: 2000 mg/L, pH: 7, optimum temperature: 40°C in 105 min operation time. Adsorption isotherm studies suggest that Langmuir isotherm is most appropriate which indicates adsorption follows chemisorption. The adsorption capacities of PX1, PX2, and PX3 are found as 309.59, 352.11, and 380.22 mg/g for Cu(II) and 299.40, 315.45, and 328.94 mg/g and for Ni(II), respectively, which is very high in comparison with many other recent literature studies. [ABSTRACT FROM AUTHOR]

The present work proposes the development of a simple and easy-to-make microfluidic paper-based analytical device (µPAD) as a prototype chromatic device for the simultaneous determination of copper and zinc in urine. The µPAD comprises a main circular sampling zone with two identical arms, each containing a circular pretreatment zone and a circular detection zone. Copper(II) and zinc(II) react with 1-(2-pyridylazo)-2-naphthol (PAN) reagent, at pH 6.0 and room temperature, to form chelates colored red and pink, respectively, that can be quantified by digital imaging analysis. The colorimetric reaction sensitivity significantly improved by coating the paper substrate surface with 5% 3-aminopropyltriethoxysilane (APTES) and applying three successive additions of standard or sample onto the sampling zone, without any prior sample preparation step. These combined analytical strategies increased the color intensity of the metal chelates formed on µPAD surface, allowing to detect the desired elements at trace level concentrations. The reaction interferences associated with the presence of foreign elements were eliminated or reduced through the addition of masking agents at different concentrations for each case. Under optimized conditions, excellent linear relationships were obtained in the range 0.1−10 µg mL−1, with determination coefficients (R2) greater than 0.9957. The limits of detection (LOD) and quantification (LOQ), respectively, were 27.1 µg L−1 and 90.3 µg L−1 for copper and 35.9 µg L−1 and 119.7 µg L−1 for zinc. The developed prototype device was validated by analyzing urine certified material samples, obtaining a good concordance without significant difference between the certified values and the measured values. Its application for clinical analysis offers simple, quick, cheap, noninvasive, and environmentally friendly measurements, which are desirable analytical features for point-of-care testing.

The state-of-the-art technology of fabricating printed copper electronics is focussed largely on thermal sintering restricting transition towards heat sensitive flexible substrates. Herein we report a pioneering technology which eliminates the need for conventional sintering. Biopolymer-stabilised copper particles are prepared such that they can be compressed at room temperature to generate air-stable films with very low resistivities (2.05 – 2.33 × 10−8 Ω m at 20 °C). A linear positive correlation of resistivity with temperature verifies excellent metallic character and electron microscopy confirms the formation of films with low porosity (< 4.6%). An aqueous ink formulation is used to fabricate conductive patterns on filter paper, first using a fountain/dip pen and then printing to deposit more defined patterns (R < 2 Ω). The remarkable conductivity and stability of the films, coupled with the sustainability of the approach could precipitate a paradigm-shift in the use of copper inks for printable electronics. [ABSTRACT FROM AUTHOR]

The electrochemical carbon dioxide reduction reaction (CO2RR) holds substantial promise for producing high‐value chemicals and fuels, drawing significant attention from both academia and industry. This work proposes an in‐situ electrodeposition method to prepare indium‐doped copper (Cu)‐based catalysts on carbon paper (Cu100Inx−CP, x=3.9, 4.5, 4.8, 5.1, and 7.6, denoting the molar ratio of In to Cu in the catalyst.). The catalysts Cu100Inx−CP were used for CO2RR to produce multi‐carbon (C2+) products. Characterization results showed that In was highly dispersed in the Cu particles at x<5.1. The Cu100In5.1−CP (containing 0.95 wt % In based on Cu) was very efficient for electrocatalytic CO2RR. The in‐situ Raman spectroscopy showed that Cu100In5.1−CP enhanced *CO intermediate adsorption and promoted the production of C2+ products due to the synergistic effect between In and Cu. In doping could suppress HER, enhanced *CO intermediate adsorption, and C−C coupling for the production of C2+ products in CO2RR. [ABSTRACT FROM AUTHOR]

In this study, practical application for the industrial-scale hydrogen evolution reaction (HER) process is established using sustainable Cu 2 CoSnS 4 embedded in paper-working electrodes. The Cu 2 CoSnS 4 is produced using a solvent-free solid-phase approach. The effect of a wide pH range of electrolytes on working electrodes for hydrogen evolution reactions is also investigated. The Cu 2 CoSnS 4 embedded paper-working electrodes exhibit goodelectrocatalytic activity for hydrogen evolution reaction with low overpotential values of 233, 310, and 261 mV vs RHE at 10 mA/cm 2 in 0.5 M H 2 SO 4 ,1 M KOH, and 1 M PBS, respectively. These designed electrodes exhibit high double-layer capacitance and electrochemical surface area for a wide pH range. In acidic, alkaline and neutral environments, the catalyst-embedded paper electrodes explicit high turnover frequencies of 2.15 s−1, 2.75 s−1, and 2.11 s−1, respectively. The temperature-dependent hydrogen evolution reaction is studied to calculate the activation energy of the cathodic electrode. Utilising chrono-amperometry for about 118 h in an acidic media, which shows that electrodes have a high degree of stability. In comparison to other previously reported work on catalyst-embedded electrodes, the Cu 2 CoSnS 4 embedded paper-working electrodes offer excellentpotential for HER activity across a wide pH range and are suitable for industrial application. • Cu 2 CoSnS 4 embedded paper working electrodes are developed for hydrogen generation. • The electrodes exhibit universal pH hydrogen evolution reaction. • Electrodes shows excellent stability upto 40hr for continuous hydrogen generation. • The electrode displays good stability at current density more than 200 mA/cm2. [ABSTRACT FROM AUTHOR]

The highly porous and binder-free flexible paper electrodes can enhance the specific capacitance of symmetric supercapacitors (SCs) due to their large surface and effective ion diffusion pathways. We synthesized the exfoliated graphite (ExG) by the thermal exfoliation method of chemically treated graphite flakes and compressed it into a paper-like thin sheet (binder-free) of ∼0.15 mm thickness. The coin cell SCs with copper (Cu) and stainless steel (SS) as current collectors have been fabricated for the electrochemical measurement. The cyclic voltammetry and galvanostatic charge/discharge measurements are investigated at various scan rates and current densities. The SCs with Cu foil as a current collector perform better than SS-based SCs. The Cu current collector-based SCs showed a specific capacitance of 37.08 mF cm−2, whereas it was ∼29.98 mF cm−2 for SS-based SCs at a 0.01 V s−1 scan rate across a 0–0.6 V potential window. Approximately no degradation in charge storage capacity for more than 15 000 cycles at 0.1 V s−1 shows the ultra-stability of the flexible ExG-based binder-free electrodes. A digital watch is powered using the fabricated pouch cell supercapacitor with copper-based current collectors to show the potential of SCs. [ABSTRACT FROM AUTHOR]

• Adding kaolin reduces the volatility and leachability of heavy metals. • Xerogel with high porosity was successfully synthesized for heavy metal adsorption. • Silica-alumina xerogel can effectively adsorb heavy metals in pyrolysis gas. • Heavy metal species can form ionic or covalent bonds with kaolinite. It is of great significance to reduce the secondary risk of heavy metals during the pyrolysis of paper sludge. This study used kaolin and alumina-silica-based xerogels to control heavy metals released during sludge pyrolysis. Pyrolyzing a mixture of sludge and 7% kaolin at 400 °C achieved high retention rates for Cu (95.85%), Zn (95.97%), Pb (97.15%), Cd (84.23%), and Cr (84.05%) when the pyrolysis tail gas was treated with 9 g of xerogel. The addition of kaolin facilitated the transformation of Cu, Zn, Pb, and Cr from the unstable fraction to the stable fraction in pyrolysis biochar, reducing their leachability. The xerogels also played a crucial role in adsorbing and stabilizing the heavy metals. The results of thermodynamic equilibrium calculations showed that Pb(g), PbS(g), PbCl 2 (g), PbCl(g), Zn(g), ZnCl 2 (g), and Cd(g) were the main gaseous products of Zn, Pb, and Cd during paper sludge pyrolysis. The Pb atoms in PbCl 2 and PbS, and the Zn atoms in ZnCl 2 bond with the oxygen atoms on the kaolin surface by covalent bonds, while the Cl atoms in PbCl and the Pb atoms of elemental lead form ionic bonds with H and O atoms on the kaolinite surface, respectively. These experimental and simulation results offer new ideas for controlling heavy metals during sludge pyrolysis. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide is an environmentally friendly bleaching chemical that is widely used in alkaline media in the pulp and paper industry. In this study, unconventional reaction conditions of the conventional bleaching Pstage were performed to evaluate its effect on cellulose. The objective was to “tailor” the cellulose degradation according to different applications, such as dissolving pulps. Different operating conditions were studied: pH variation (alkaline or acidic medium), as well as the addition of Cu(II) or the Cu(II)-phenanthroline complex. The hypotheses considered were (1) Using H2O2 in unconventional conditions will favor hemicelluloses removal after depolymerization and will lead to the desired cellulose degradation, and (2) H2O2 oxidation carried out under unconventional conditions will favor the dissolving ability of cellulose. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (μPADs) have been developed for use in a variety of diagnosis and analysis fields. However, conventional μPADs with an open-channel system have limitations for application as analytical platforms mainly because of the evaporation and contamination of the sample solution. This study demonstrates the design and fabrication of an enclosed three-dimensional(3D)-μPAD and its application as a primary early analysis platform for ionic contaminants. To generate the hydrophobic PDMS barrier, double-sided patterning is carried out using a PDMS blade-coated stamp mold that is fabricated using 3D printing. The selective PDMS patterning can be achieved with controlled PDMS permeation of the cellulose substrate using 3D-designed stamp molds. We find the optimal conditions enabling the formation of enclosed channels, including round shape pattern and inter-pattern distance of 10 mm of stamp design, contact time of 0.5 min, and spacer height of 300 µm of double-sided patterning procedure. As a proof of concept, this enclosed 3D-μPAD is used for the simultaneous colorimetric detection of heavy metal ions in a concentration range of 0.1–2000 ppm, including nickel (Ni2+), copper (Cu2+), mercury (Hg2+), and radioactive isotope cesium-137 ions (Cs+). We confirm that qualitative analysis and image-based quantitative analysis with high reliability are possible through rapid color changes within 3 min. The limits of detection (LOD) for 0.55 ppm of Ni2+, 5.05 ppm of Cu2+, 0.188 ppm of Hg2+, and 0.016 ppm of Cs+ are observed, respectively. In addition, we confirm that the analysis is highly reliable in a wide range of ion concentrations with CV values below 3% for Ni2+ (0.56%), Cu2+ (0.45%), Hg2+ (1.35%), and Cs+ (2.18%). This method could be a promising technique to develop a 3D-μPAD with various applications as a primary early analysis device in the environmental and biological industries. [ABSTRACT FROM AUTHOR]

This paper presents the development of cheap and selective Paper-based Analytical Devices (PADs) for selective Pd(II) determination from very acidic aqueous solutions. The PADs were obtained by impregnating two cm-side squares of filter paper with an azoic ligand, (2-(tetrazolylazo)-1,8 dihydroxy naphthalene-3,6,-disulphonic acid), termed TazoC. The so-obtained orange TazoC-PADs interact quickly with Pd(II) in aqueous solutions by forming a complex purple-blue-colored already at pH lower than 2. The dye complexes no other metal ions at such an acidic media, making TazoC-PADs highly selective to Pd(II) detection. Besides, at higher pH values, other cations, for example, Cu(II) and Ni(II), can interact with TazoC through the formation of stable and pink-magenta-colored complexes; however, it is possible to quantify Pd(II) in the presence of other cations using a multivariate approach. To this end, UV-vis spectra of the TazoC-PADs after equilibration with the metal ions solutions were registered in the 300–800 nm wavelength range. By applying Partial Least Square regression (PLS), the whole UV-vis spectra of the TazoC-PADs were related to the Pd(II) concentrations both when present alone in solution and also in the presence of Cu(II) and Ni(II). Tailored PLS models obtained with matrix-matched standard solutions correctly predicted Pd(II) concentrations in unknown samples and tap water spiked with the metal cation, making the method promising for quick and economical sensing of Pd(II). [ABSTRACT FROM AUTHOR]

The employment of ultra‐thin lithium metal anode with high loading cathode is the key to realizing high‐energy‐density rechargeable lithium batteries. Ultra‐thin lithium foils are routinely loaded on a copper substrate in batteries, however, the close contact of these two metals causes galvanic corrosion in the presence of electrolyte, which results in irreversible consumption of lithium and decomposition of electrolyte. Herein, a lightweight and highly conductive flexible graphite paper (GP) is applied to replace Cu foil as the current collector for lithium metal anode. It is demonstrated that the application of GP prevents galvanic corrosion and maintains intimate and steady contact between Li foil and GP current collector during cycling, thereby improving the electrochemical performance of the battery. A 1.08 Ah pouch cell assembled with Li@GP anode and LiNi0.8Co0.1Mn0.1O2 cathode exhibits a long lifetime of 240 cycles with a capacity retention of 91.6% under limited Li, high cathode loading and lean electrolyte conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Concept of paper-based extractive polymeric sensing network was firstly applied. • Metal separation, preconcentration and colorimetric analysis were combined. • The detection of Cu2+ was used as proof of concept. • The paper coated with the proposed matrix showed good water-wicking properties. • The proposed device was applied to tap and environmental samples successfully. The concept of using an extractive polymeric sensing network on a paper-based substrate for the pretreatment of samples in the colorimetric analysis of heavy metals is demonstrated with the determination of Cu2+ in aqueous samples. The newly developed paper-based device combines the advantages of both liquid–liquid extraction-based separation and the analytical capabilities of microfluidic paper-based analytical devices (μPADs). The preconcentrating extractive polymeric network composed of 53.5 wt% poly(vinyl chloride) (PVC), 45 wt% extractant (di-(2-ethylhexyl)phosphoric acid (D2EHPA)) and 1.5 wt% dye (1-(2′-pyridylazo)-2-naphthol (PAN)), coated on filter paper, shows good water-wicking properties, allowing the transmission of high sample volumes. This results in significant analyte preconcentration. The extractant (D2EHPA) selectively binds Fe3+ and Zn2+ which otherwise will compete with Cu2+ in its colour reaction with PAN at the chosen pH of 3.0. The device's capacity to process higher sample volumes resulting in higher sensitivity is increased by the integration of several filter paper absorption layers. The optimized device is characterized by a limit of detection (LOD) for tap and environmental waters of 3.4 and 9.6 µg/L, respectively; stability of 51 days if stored in a refrigerator; and total analysis time (from sample insertion to colour detection) of less than 5 min. [ABSTRACT FROM AUTHOR]

Complexes of lanthanide ions, such as Eu(III) (red light emission) and Tb(III) (green light emission), with proper ligands can be highly luminescent and color-tunable, also attaining yellow and orange emission under UV radiation. The ligands employed in this work were poly(sodium acrylate), working as polymeric matrix, and 1,10-phenanthroline, taking advantage of its antenna effect. Possibilities of color display were further enhanced by incorporating a cationic polyfluorene with blue emission. This strategy allowed for obtaining cyan and magenta, besides the aforementioned colors. Uncoated cellulose paper was impregnated with the resulting luminescent inks, observing a strong hypsochromic shift in excitation wavelength upon drying. Hence, while a cheap UV-A lamp sufficed to reveal the polyfluorene's blue emission, shorter wavelengths were necessary to visualize the emission due to lanthanide ions as well. The capacity to reveal, with UV-C radiation, a full-color image that remains invisible under natural light is undoubtedly useful for anti-counterfeiting applications. Furthermore, both lanthanide ion complexes and polyfluorenes were shown to have their luminescence quenched by Cu(II) ions and nitroarenes, respectively. [ABSTRACT FROM AUTHOR]

Over time, the risk assessment of dermal exposure to pollutants in print paper products has received considerable attention. Most studies have focused on organic pollutants, especially bisphenol A (BPA). However, little is known about the levels of trace elements in print paper products, despite the knowledge that these elements are components of printing inks and toners. This study was aimed at determining the concentrations of trace elements in 5 types of paper products, namely bulletins, magazines, special events program booklets, handbills, and newspapers. The average daily intake (ADI) of each element was subsequently estimated through dermal exposure to the papers. The detection frequency of the elements of interest was high (nearly 100%) in most paper products, with the exception of chromium, whose detection was low. In contrast, Ag was not detected in any sample. The levels of the elements in the paper products were low and comparable to those found in other personal and consumer products with the potential for skin contact. The range values of estimated ADIs were 1.70–3.90E-08, 2.30–18.2E-10, 2.60–16.4E-09, 3.65–5.75E-08, 1.29–4.38E-08, 6.23–15.6E-10, 1.51–2.80E-10, 1.43–9.16E-09, 0.00–9.47E-09, and 4.68–220E-08 mg/kg bw/day for Mn, Co, Ni, Cu, Zn, As, Cd, Pb, Cr and Fe respectively. These values were well below the dermal standard reference doses (R f D) for each element. The present results indicate that dermal exposure to trace elements from print paper products was low and does not pose significant risks for toxic (non-carcinogenic) effects on humans. • Previous efforts have focused on the risk assessment of organic contaminants in print paper products. • Limited attention accorded to risk assessment of trace elements in print paper products • Human dermal exposure to trace elements via print paper products was low • Exposure to trace elements via print paper products has low risks of non-carcinogenic events. [ABSTRACT FROM AUTHOR]

Improving the performance of porous nickel-based material used widely in the energy field is necessary. Alloying and increasing the specific surface area are essential approaches. This study used rice paper (Chinese traditional calligraphy and painting paper) as biomass templates to prepare hierarchical porous Ni and Ni-Cu foils (Nip and NiCup) with a thickness of about 60 μm by impregnating and high-temperature reduction process. The Ni3S2/Nip electrodes were prepared by an in situ-grown Ni3S2 nanosheet array on the struts of Nip via a hydrothermal process. Two modification methods using Cu-added alloying and Ni-S nanosheet growing were compared to determine their effects on the microstructure, phase, and performance in methanol oxidation (MOR) and urea oxidation (UOR). The results showed that both alloying effects and morphology control can promote MOR and UOR. Compared to the current density value of Nip at 0.8 V, the values of the preferred Ni10Cup and nanosheet array Ni3S2/Nip increased by 24.5% and 27.3% for methanol oxidation and by 15.4% and 38.4% for urea oxidation, respectively. Adding Cu helped to improve electron transfer and facilitated the transition from Ni2+ to Ni3+. The large specific surface area of Ni3S2 nanosheets provided more active sites for the reaction. Compared to Ni10Cup, Ni3S2/Nip with a lower impedance value exhibits better electrocatalytic performance and stability, achieving peak current densities of 269.7 mA cm−2 (MOR) and 303.9 mA cm−2 (UOR) at 0.8 V, maintaining 91.2% (MOR) and 102.4% (UOR) of the initial peak current density after 2000 cycles. The foil electrodes obtained under both modification strategies can be used as anode material in portable cells, and might also be applied to the oxidation of other small organic molecules. [ABSTRACT FROM AUTHOR]

The potential reach of point-of-care (POC) diagnostics into daily routines for exposure to reactive oxygen species (ROS) and Cu in aerosolized particulate matter (PM) demands that microfluidic paper-based analytical devices (μPADs) take into consideration the simple detection of these toxic PM components. Here, we propose μPADs with a dual-detection system for simultaneous ROS and Cu(II) detection. For colorimetric ROS detection, the glutathione (GSH) assay with a folding design to delay the reaction yielded complete ROS and GSH oxidation, and improved homogeneity of color development relative to using the lateral flow pattern. For electrochemical Cu(II) determination, 1,10-phenanthroline/Nafion modified graphene screen-printed electrodes showed ability to detect Cu(II) down to pg level being low enough to be applied to PM analysis. No intra- and inter-interference affecting both systems were found. The proposed μPADs obtained LODs for 1,4-naphthoquinone (1,4-NQ), used as the ROS representative, and Cu(II) of 8.3 ng and 3.6 pg, respectively and linear working ranges of 20 to 500 ng for ROS and 1 × 10−2 to 2 × 102 ng for Cu(II). Recovery of the method was between 81.4 and 108.3% for ROS and 80.5–105.3% for Cu(II). Finally, the sensors were utilized for simultaneous ROS and Cu(II) determination in PM samples and the results statistically agreed with those using the conventional methods at 95% confidence. [ABSTRACT FROM AUTHOR]

The global prevalence of diabetes mellitus, a serious chronic disease with fatal consequences for millions annually, is of utmost concern. The development of efficient and simple devices for monitoring glucose levels is of utmost significance in managing diabetes. The advancement of nanotechnology has resulted in the indispensable utilization of advanced nanomaterials in high-performance glucose sensors. Modulating the morphology and intricate composition of transition metals represents a viable approach to exploit their structure/function correlation, thereby achieving optimal electrocatalytic performance of the synthesized catalysts. Herein, a sensitive and rapid Cu-encapsulated Cu 2 S@nitrogen-doped carbon (Cu@Cu 2 S@N–C) hollow nanocubes-functionalized microfluidic paper-based analytical device (μ-PAD) was fabricated. Through a delicate sacrificial template/interface technique and thermal decomposition, inter-connected hollow networks were formed to boost the active sites, and the carbon shell was coated to protect Cu from being oxidation. For application, the constructed μ-PAD is used for glucose sensing utilizing an origami automated sample pretreatment system enabled by a simple application of strong alkaline solution on wax paper. Under optimal circumstances, the Cu@Cu 2 S@N–C electrochemical biosensor exhibits broad detection range of 2–7500 μM (R2 = 0.996) with low detection limit of 0.16 μM (S/N = 3) and high sensitivity of 1996 μA mM−1 cm−2. Additionally, the constructed μ-PAD also exhibited excellent selectivity, stability, and reproducibility. By rationally designing the double-shell hollow nanostructure and introducing Cu-encapsulated inner layer, the synthesized Cu@Cu 2 S@N–C hollow nanocubes show large specific surface area, short diffusion channels, and high stability. The proposed origami μ-PAD has been successfully applied to serum samples without any additional sample preparation steps for glucose determination, offering a new perspective for early nonenzymatic glucose diagnosis. [Display omitted] • Cu@Cu 2 S@N–C hollow nanocubes-based origami μ-PAD sensor was fabricated. • Cu@Cu 2 S@N–C hollow nanocubes possessed large specific surface area and high stability. • Cu@Cu 2 S@N–C hollow nanocubes exhibited excellent electrocatalytic performance for glucose. • The proposed sensor was applied for glucose detection without any additional sample preparation steps. [ABSTRACT FROM AUTHOR]

Iron and copper are essential for all living organisms, and their balance is crucial as both deficiency and excess can cause health problems. Therefore, this study presents a colorimetric method for detecting Fe3⁺ and Cu2⁺ ions in aqueous samples using silver nanoparticles (AgNPs) synthesised from Ocimum sanctum (Tulasi) leaf extract (TLE). It is observed that AgNPs show optimum plasmonic properties at a precursor-leaf extract ratio of 1:5, reaction temperature of 60 °C and reaction time of 2 h. The AgNPs exhibit the face-centred cubic (fcc) structure and show a surface plasmon resonance peak at 413 nm, hydrodynamic size of 18 ± 5 nm, zeta potential of − 25.5 mV and particle size of 57 nm. FTIR spectra confirm the stabilisation of AgNPs. It is worthy to note that, AgNPs exhibit selective detection of Fe3⁺ and Cu2⁺ over other metal ions and the detection mechanism is proposed based on the reduction potential values. The quantitative detection range for Fe3⁺ and Cu2⁺ are found to be 0–800 μM and 0–600 μM, with the detection limits of 9.1 µM and 19.5 µM, respectively. Additionally, AgNP-based paper sensors for Cu2⁺ detection show qualitative and quantitative colorimetric performance with a detection limit of 23.1 µM. These findings suggest that both AgNPs solution and AgNP-based paper sensors are the potential candidates for metal ion detection. [ABSTRACT FROM AUTHOR]

The combination of electron-deficient viologen ligands with electron-rich POMs is a typical acceptor–donor system that has recently received much attention. Under solvothermal and hydrothermal conditions, by introducing three symmetric viologen ligands into POM-based hybrid materials, we successfully constructed four POMs–viologen inorganic–organic hybrid compounds, namely (1,3-bcbpy)2·(δ-Mo8O26) (1) (1,3-bcbpy·2Cl = 1,1′-bis(3-carboxybenzyl)-4,4′-bipyridine dichloride), {CoII(1,4-bcbpy)2(H2O)2[H2(β-Mo8O26)]}·2H2O·2CH2O (2), (1,4-bcbpy)2·(δ-Mo8O26)·2H2O (3) (1,4-bcbpy·2Cl = 1,1′-bis(4-carboxybenzyl)-4,4′-bipyridine dichloride, CH2O = formaldehyde), and {CuII(1,1-pmbby)2(H2O)[H2(β-Mo8O26)2]}·5H2O·C2H7N (4) (1,1-pmbby·2Cl = 1,1′-[1,4-phenylbis(methylene)]bis-(4,4′-bipyridine)dichloride, C2H7N = dimethylamine). These four compounds exhibit different fascinating structures, especially compound 4 is a typical metal–organic framework. Compounds 1–4 exhibit good discoloration behaviors under various external stimuli. For example, compounds 1–4 showed a positive response to the irradiation from a 300 W Xe lamp. When a positive voltage was applied to the ECD based on compounds 1–4, 1/2/3/4-ECD underwent a significant color conversion. What's more, compound 4 also showed obvious discoloration results after heating. In a word, 1–4 are multifunctional discoloration materials under different external stimuli. In addition, the coated filter paper prepared based on compound 3 can be used as a new printing material medium and can be successfully applied in erasable inkless printing and dual anti-counterfeiting. [ABSTRACT FROM AUTHOR]

The metal-organic frameworks (MOFs) nanozyme-mediated paper-based analytical devices (PADs) have shown great potential in portable visual determination of phenolic compounds in the environment. However, most MOF nanozymes suffer from poor dispersibility and block-like structure, which often prompts deposition and results in diminished enzymatic activity, severely hindering their environmental applications. Here, we proposed colorimetric PADs for the visual detection of dichlorophen (Dcp) based on its significant inhibitory effect on the two-dimensional (2D) MOF nanozyme activity. Specifically, we synthesized a 2D Cu TCPP (Fe) (defined as 2D-CTF) MOF nanozyme exhibiting excellent dispersibility and remarkable peroxidase-like (POD-like) activity, which could catalyze the oxidation and subsequent color change of 3,3′,5,5′-tetramethylbenzidine even under neutral conditions. Notably, the POD-like activity of 2D-CTF demonstrated a unique response to Dcp because of the occupation of Fe–N 4 active sites on the 2D-CTF. This property enables the use of 2D-CTF as a highly efficient catalyst to develop colorimetric PADs for naked-eye and portable detection of Dcp. We believe that the proposed colorimetric PADs offer an efficient method for Dcp assay and open fresh avenues for the advancement of colorimetric sensors for analyzing of phenolic toxic substances in real samples. [ABSTRACT FROM AUTHOR]

In the current research work "4-{[1-(2,5-dihydroxyphenyl)ethylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one" chemosensor (C1) synthesized by condensation reaction using "4-amino-1,2-dihydro-1,5-dimethyl-2-phenylpyrazol-3-one" and "2,5-dihydroxy actophenone" was used as the effective sensor of metal ion. The C1 shows absorption peak at 326 nm due to the C = C bond (π-π* transition), while the absorption peak at 364 nm is caused by the C = O bond (n-π* transition). In the presence of copper, C1 only demonstrated a redshift in absorption peak from 364 to 425 nm. Even in the presence of other competing metal ions, the hypsochromic shift of the absorption band and the quenching of the fluorescence emission intensity were different for detecting Cu2+, in CH3OH-H2O (v/v = 6:4). The capacity of the C1 to bind with Cu2+ was further proved using DFT simulations. The complex C1 + Cu2+ has a HOMO–LUMO energy gap of 2.8002 eV, which is lesser than C1 (2.9991 eV) showing improvement in the stability of the C1 + Cu2+ complex. Using the Benesi-Hildebrand and Scatchard plots, calculated Kb values were to be 47,340 and 48369 M−1 respectively, showing the creation of stable complexation between Cu2+ and C1 with 1:1 stoichiometry. The limit of detection (LOD) for Cu2+ ion was 649 nM. Strip sheets were also built and tested to detect varying amounts of Cu2+ in aqueous solution, and their color change suggested that they might be used for on-site Cu2+ detection in polluted water. [ABSTRACT FROM AUTHOR]

An enhanced ratiometric fluorescence sensor was built for on-site visual detection of doxycycline (DOX) through the interaction with bovine serum albumin on the surface of red emissive copper nanoclusters. Upon the addition of weakly fluorescent DOX, the red fluorescence from copper nanoclusters gradually decreased through the inner-filter effect (IFE), while a green fluorescence appears and significantly increases, forming an interesting fluorescent isosbestic point, which was assigned to DOX due to sensitization effect of bovine serum albumin. On the basis of this ratiometric fluorescence, the system possessed good limit of detection (LOD) of 45 nM and excellent selectivity for DOX over other tetracyclines. Based on these findings, a paper-based sensor has been fabricated for distinct visual detection of trace DOX and combined with smartphone color recognizer for quantitative detection of DOX (LOD = 83 nM). This method shows broad application prospects in environmental monitoring and food safety. [ABSTRACT FROM AUTHOR]

The ecological environment is increasingly damaged due to the impact of mineral oil extraction and leakage. As a kind of sustainable resource, a vegetable oil transformer has bright application prospects in future. However, the stability of vegetable oil has always been a problem to be solved. In addition, the metallic copper inside the transformer has a certain catalytic effect on the deterioration of vegetable oil. In this article, a copper–oil–paper insulation model is established. Based on the molecular dynamics simulation method, the catalytic mechanism of copper on the deterioration of oil-paper insulation is revealed from the microscopic level. Then, the effects of temperature, contact area, and oxygen on the catalytic effect of copper are discussed. The results show that copper could accelerate the decomposition of oil-paper insulation by attracting H atoms and O atoms in oil-paper. The increase in temperature accelerates the progress of the catalytic reaction and aggravates the deterioration of oil-paper insulation. The oxygen concentration has an important influence on the catalytic reaction of copper. As the oxygen concentration increases, the catalytic effect of copper is weakened. The abovementioned research could provide some theoretical reference for further exploration of effective oil-paper insulation deterioration protection technology. [ABSTRACT FROM AUTHOR]

In this study, we have developed a self-standing nanocomposite mat, which combined of copper (benzene 1,3,5-tricarboxylic acid) MOFs (Cu(BTC)MOFs) and carbon nanofibers (CNFs) and used as an enzyme-free electrochemical sensor for detection of 4-nitrophenol in phosphate buffer (pH = 7). The high specific surface area and variety of functional active adsorption sites of as-developed hybrid mat facilitated faster transport of analyte molecules across the electrode-electrolyte interface. The Cu(BTC)MOF@CNF-modified glassy carbon electrode (Cu(BTC)MOF@CNF/GCE) demonstrated improved electrocatalytic responses toward 4-nitrophenol. The as-developed electrode showed that an excellent sensitivity (2.3429 μA μM−1 cm−2) with good selectivity and outstanding cyclic stability. The hybrid sensor exhibited a widespread linear range from 5.0 to 400 µM along with a low detection limit of 87.12 nM, for 4-nitrophenol determination. The present sensor electrode showed anti-interference property and high selectivity with good storage stability up to 30 days. Lastly, the sensing performances of the Cu(BTC)MOF@CNF/GCE toward para-nitrophenol in real samples give the satisfactory results, which proved the practical applicability of the present hybrid material. Furthermore, the real sample analyses results validated through HPLC results, and it was observed that the current results are in comparable with high-performance liquid chromatography data. [ABSTRACT FROM AUTHOR]

This work describes the development of a microfluidic paper-based analytical device (μPAD) for the determination of copper in fresh and marine waters. A functionalized rhodamine-based chelator was synthesized and used as a chromogenic reagent, forming a highly intense pink complex with the analyte. The aim was to create a paper device that offers optimal performance and provides in-situ , rapid and cost-effective analysis in line with World Health Organization guidelines. The influence on the determination of several physical and chemical parameters was evaluated aiming to achieve the best performance. Under optimised conditions, a linear correlation was established in the range of 0.05–0.50 mg L−1 of copper, with a limit of detection of 10 μg L−1. The accuracy of the proposed method was assessed by comparing the results obtained with the developed μPAD and the results obtained with Inductively Coupled Plasma measurements (RE < 10 %). Recovery studies were also performed using different types of water samples with no need for any prior sample pre-treatment: tap, well, river and seawater. The average recovery percentage of 101 % (RSD = 4.3 %) was obtained, a clear indication of no multiplicative matrix interferences. [Display omitted] • Copper determination in waters using a handheld-size microfluidic paper-based device incorporating a synthesized chelator. • Quantification of copper validated by comparison with Inductively Coupled Plasma – Optical Emission Spectrometer (ICP-OES). • Environmentally friendly assembly as there is no need for a wax printer. [ABSTRACT FROM AUTHOR]

This manuscript aims to illustrate some of the current industrial and biological applications of copper oxide (Cu2O) nanoparticles, where nanoparticles are of particular interest because of their multiple applications, as well as antibacterial and antiviral. In addition to the industrial applications such as ink permeability, sensing and carriers in solar cells, the obvious properties of finely processed Cu2O is discussed along with different preparation methods through which Cu2O nanoparticles are obtained. It is widely accepted that pulsed laser ablation is one of the most successful Cu2O fabrication techniques., where this study focus on preparation and characterization copper nanoparticles doped Silver nanoparticles (Cu2O@Ag) for optoelectronics, and bio-applications I can't understand this sentence, please revise it. [ABSTRACT FROM AUTHOR]

High levels of Cu (II) in the human body can cause kidney dysfunction, liver cirrhosis, and many neurological diseases, such as Wilson's disease (WD). Therefore, rapid and efficient detection of Cu (II) in urine is highly essential. First, by a simple multiple seeded growth method, the gold nanoclusters (Au NCs) embedded metal-organic framework (ZIF-8) is decorated on cellulose paper to generate a fluorescent Au NCs@ZIF-8 paper. Then the Au NCs@ZIF-8 paper is loaded on the fluidic cartridge integrated with the syringe for ultra-sensitive urine copper detection. The fluorescence paper is intercalated in a reusable fluidic cartridge and attached to a syringe, allowing the fluidic cartridge to flow a amount of samples through the paper. The interaction of Cu (II) with in situ growth of Au NCs@ZIF-8 on the paper induced fluorescence quenching, which fluorescence images can be recorded and analyzed by the portable smartphone-assisted device. Furthermore, a large amount of sample solution was flowed through the Au NCs@ZIF-8 paper, enabling more Cu (II) to react with the Au NCs@ZIF-8 paper on the novel paper-based analytical device (nPAD). Cu (II) detection can be completed by nPAD in 20 mins, and the limit of detection was as low as 9.2 nM. We show the value of the paper device for on-site detection of copper (II) and indicate that it has excellent potential for clinical applications and environmental monitoring. • A novel paper-based sensor was employed for ultrasensitive and accurate detection of Cu2+. • A fluorescent paper-based device is prepared by in-situ embedding the Au NCs@ZIF-8 on cellulose paper. • Au NCs@ZIF-8 paper equipment integrated with the fluidic cartridge dramatically boosts the sensitivity of detection. • The nPDA based on Au NCs@ZIF-8 paper equipment achieved a nanomole detection limit. • The nPDA was clinically validated with excellent accuracy for universal detection of Cu2+ in urine. [ABSTRACT FROM AUTHOR]

It is crucial to understand the effects caused by experimental parameters such as temperature, light, and food type on lab and field-based ecotoxicology experiments, as these variables, and combinations thereof, can affect results. The type of substrate used in exposure experiments, however, is generally assumed to have no effect. This may not always be correct. The metabolic changes in the freshwater crustacean, Austrochiltonia subtenuis exposed to copper, using three common substrates, gauze; toilet paper; and cellulose were investigated. Substrate alone did not affect survival, but each substrate elicited a different metabolic response and adult and juvenile amphipods had different substrate preferences. Several classes of metabolites were shown to change in response to different substrates and toxicant. These included disaccharides, monosaccharides, fatty acids, and tricarboxylic acid cycle intermediates. The results illustrate that metabolomic responses can differ in response to experimental factors that were previously thought not to be significant. In fact, our data indicate that substrate should be viewed as an experimental factor as important to control for as more well-known confounders such as temperature or food, thus challenging the current paradigm. Assuming substrate type has no effect on the experiment could potentially lead to errors in contaminant toxicity assessments. We propose that ideal good practise would be that all experimental factors should be evaluated for their potential influence on metabolomic profiles prior to contaminant response experiments being undertaken. [ABSTRACT FROM AUTHOR]

A scalable, and cost-effective method was employed to prepare self-supported CuSn bimetallic catalyst on carbon paper. The obtained CuSn catalyst demonstrates high faradaic efficiency of CO around or above 90% at a broad potential range from −0.7 to −1.8 V vs. reversible hydrogen electrode, greatly surpassing Cu or Sn counterparts. [ABSTRACT FROM AUTHOR]

[Display omitted] • GQD-DDT and GQD-MPA was synthesized using novel hydrothermal protocol. • GQD-DDT and GQD-MPA was used for the identification of cations using colorimetric and spectrophotometric assay. • GQD-DDT and GQD-MPA have well activity for ion sensing in aqueous solution. This study describes the synthesis of various types of thiolated-graphene quantum dots (GQDs) for the simultaneous multi-sensing of heavy metal ions using one-droplet microfluidic paper-based analytical devices (OD- µ PADs). For the first time, functionalized GQDs were synthesized and stabilized on the surface of hydrophobic fiber-glass with simple manufacturing and assembly strategy towards colorimetric chemosensing of ions including iron, copper, cobalt, mercury, chrome, manganese, and nickel. For this purpose, GQDs are functionalized by various organic species including cysteamine, decanethiol, and mercaptopropionic acid (MPA) towards specific electrostatic interaction with metal ions of Fe (II), Cu (II), Co(II), Hg (II), Mn (II), and Ni (II). Therefore, an innovative GQDs-based miniaturized chemo-system was proposed for the environmental analysis. Additionally, the results were confirmed using fluorescence spectrometry as an optical detection method. Finally, this simple and efficient colorimetric platform was used for facile metal ions detection in human urine models, and environmental fluids, which can provide a commercial device for sensing contaminants by non-professional users in biomedical/environmental mixture. As an economical technique, this platform presents a "mix-and-sense" system without dye (as a side substance) or chemical treatments. The low instrumental requirements, the color uniformity, and the disposability of OD- μ PADs approve the commercial application of the engineered ion-chemosensor. [ABSTRACT FROM AUTHOR]

As a unique class of dynamic nanostructures, biomimetic DNA walking machines that exhibit geometrical complexity and nanometre precision have gained great success in photoelectrochemical (PEC) bioanalysis. Despite certain achievements, the slow reaction kinetics and low processivity severely restrict the amplification efficiency of the DNA walker-mediated biosensors. Herein, by taking advantage of efficient DNA rolling machines, a three-dimensional (3D) DNA nanomachine-mediated paper-based PEC device for speedy ultrasensitive detection of miR-486–5p was successfully constructed. To achieve it, a novel In 2 S 3 /SnS 2 sensitized heterojunction was firstly in-situ grown on the Au-modified paper fibers and implemented as the photoanode with effective separation of photogenerated carriers to achieve an enhanced initial photocurrent. Subsequently, the copper hexacyanoferrate(II)-modified CuO nanosphere was introduced as a multifunctional signal regulator via the competitive capture of electron donors and photon energy with the photoelectric layer for efficiently quenching the PEC signal. With the introduction of targets, the DNAzyme-driven DNA nanomachine with editable motion modes was gradually activated and it could continuously cleave the tracks DNA labeled quenching probes, finally achieving the recovery of PEC signal. As a proof of concept, the elaborated paper-based PEC device presented a wide linear range from 0.1 fM to 100 pM and a detection limit of 35 aM for miR-486–5p bioassay. This work provides an innovative insight to the exploitation of DNA nanobiotechnology and nucleic acid signal amplification strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sonication improves the absorption of metallic salt in the paper. • Ultrasound catalyzes the synthesis of metallic nanoparticles. • A longer sonication time during salt absorption increases the number of nanoparticles obtained. • Nanoparticles obtained by sonochemistry are an easy and reproducible method to modify paper. This work focuses on a systematic method to produce Ag, Cu, and Ag/Cu metallic nanoparticles (MNPs) in situ assisted with ultrasound on cellulose paper. By tuning the concentration of AgNO 3 and CuSO 4 salt precursors and ultrasound time, combined with a fixed concentration of ascorbic acid (AA) as a reducing agent, it was possible to control the size, morphology, and polydispersity of the resulting MNPs on cellulose papers. Notably, high yield and low polydispersity of MNPs and bimetallic nanoparticles are achieved by increasing the sonication time on paper samples pre-treated with salt precursors before reduction with AA. Moreover, mechanical analysis on paper samples presenting well-dispersed and distributed MNPs showed slightly decreasing values of Young's modulus compared to neat papers. The strain at break is substantially improved in papers containing solely Ag or Cu MNPs. The latter suggests that the elastic/plastic transition and deformation of papers are tuned by cellulose and MNPs interfacial interaction, as indicated by mechanical analysis. The proposed method provides insights into each factor affecting the sonochemistry in situ synthesis of MNPs on cellulose papers. In addition, it offers a straightforward alternative to scale up the production of MNPs on paper, ensuring an eco-friendly method. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new rhodamine based chemosensor 1 was synthesized and characterized. • Selectively detect Co2+/Cu2+ in different solvent systems (MeCN and DMF). • Sensor 1 as copper (II) ion detector can be reused with proper treatment. • Filter paper test strip for detection of Co2+ and Cu2+ in pure aqueous solution. • Sensor 1 showed no significant cytotoxicity towards CCD-18Co and HT-29 cell lines. 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 Co2+/Cu2+ 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 Co2+/Cu2+ 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 Co2+ complex and 1:2 stoichiometry for Cu2+ complex through Job's plot, IR spectroscopy, mass spectrometry and 1H 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 Co2+ and Cu2+ in pure aqueous media. The MTT assay was conducted in order to determine the cytotoxicity of sensor 1 towards human cell lines. [ABSTRACT FROM AUTHOR]

Non-thermal plasma (NTP) is a well-known decontamination tool applicable for a wide range of microorganisms and viruses. Since the recent COVID-19 pandemic highlighted the need to decontaminate all daily used items, it is highly desirable to address the applicability of NTP, including its possible harmful effects. To the best of our knowledge, a comprehensive characterization of NTP effects on sensitive materials is still lacking. We investigated the potential damage to common materials of daily use inflicted by air atmospheric NTP generated in Plasmatico v1.0. The materials tested were paper, various metals, and passive and active electronic components modelling sensitive parts of commonly used small electronic devices. The NTP-exposed paper remained fully usable with only slight changes in its properties, such as whitening, pH change, and degree of polymerization. NTP caused mild oxidation of copper, tinned copper, brass, and a very mild oxidation of stainless steel. However, these changes do not affect the normal functionality of these materials. No significant changes were observed for passive electronic components; active components displayed a very slight shift of the measured values observed for the humidity sensor. In conclusion, NTP can be considered a gentle tool suitable for decontamination of various sensitive materials. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (µPADs) have been successfully developed using dual detection: electrochemical and colorimetric systems. The µPADs have the potential to be used as Pb(II), Cd(II), and Cu(II) sensors to test the quality of water. The fabrication process uses hot embossing and screen-printing methods. The working electrode in the electrochemical zone was enhanced by the bismuth metal deposition process, while in the colorimetric zone, the gold nanoparticles modified with thioctic acid and dansylhydrazine (TA-Au-DNS) were used as a colorimetric sensor to detect Cu. The basic material of µPADs was characterized using a Fourier-transform infrared (FTIR) and a contact angle meter (CAM). In the electrochemical zone, the signals of square wave anodic stripping voltammetry (SWASV) resulted in good detection of Pb(II) and Cd(II) (from 0 to 100 ppb) with a limit of detection of 1.588 and 1.42 ppb, respectively. In the colorimetric zone, the performance of TA-Au-DNS for detecting Cu metal was obtained from readings through the red-green-blue (RGB) sensor as a miniature of µPADs reader. The LOD, LOQ, and average Vx0 (linearity values) in the detection of Cu(II) (from 58 to 100 ppb) are 8.51 ppb, 28.36 ppb, and 0.41%, respectively. [ABSTRACT FROM AUTHOR]

Despite modern chemistry's success in providing affordable fertilizers for feeding the population and supporting the ammonia industry, ineffective nitrogen management has led to pollution of water resources and air, contributing to climate change. Here, we report a multifunctional copper single-atom electrocatalyst-based aerogel (Cu SAA) that integrates the multiscale structure of coordinated single-atomic sites and 3D channel frameworks. The Cu SAA demonstrates an impressive faradaic efficiency of 87% for NH3 synthesis, as well as remarkable sensing performance with detection limits of 0.15 ppm for NO3- and 1.19 ppm for NH4+. These multifunctional features enable precise control and conversion of nitrate to ammonia in the catalytic process, facilitating accurate regulation of the ammonium and nitrate ratios in fertilizers. We thus designed the Cu SAA into a smart and sustainable fertilizing system (SSFS), a prototype device for on-site automatic recycling of nutrients with precisely controlled nitrate/ammonium concentrations. The SSFS represents a forward step toward sustainable nutrient/waste recycling, thus permitting efficient nitrogen utilization of crops and mitigating pollutant emissions. This contribution exemplifies how electrocatalysis and nanotechnology can be potentially leveraged to enable sustainable agriculture. [ABSTRACT FROM AUTHOR]

The existence of heavy metals and organic pollutants in wastewater is a threat to the ecosystem and a challenge for researchers to remove using common technology. Herein, a facile one-step in situ oxidative polymerization synthesis method has been used to fabricate polyaniline@waste cellulosic nanocomposite adsornt, polyaniline-embedded waste tissue paper (PANI@WTP) to remove copper(II) and phenol from the aqueous solution. The structural and surface properties of the synthesized materials were examined by XRD, FTIR, TEM, and a zeta potential analyzer. The scavenging of the Cu(II) and phenol onto the prepared materials was investigated as a function of interaction time, pollutant concentration, and solution pH. Advanced kinetics and isotherms modeling is used to explore the Cu(II) ion and phenol adsorption mechanisms. The synthesized PANI@WTP adsorbent showed a high intake capacity for Cu(II) than phenol, with the maximum calculated adsorption capacity of 605.20 and 501.23 mg g−1, respectively. The Langmuir equilibrium isotherm model is well-fitted for Cu(II) and phenol adsorption onto the PANI@WTP. The superior scavenging capability of the PANI@WTP for Cu(II) and phenol could be explained based on the host–guest interaction forces and large active sites. Moreover, the efficiency of the PANI@WTP for Cu(II) and phenol scavenging was excellent even after the five cycles of regeneration. [ABSTRACT FROM AUTHOR]