Miniaturized Electrochemical Gas Sensor with a Functional Nanocomposite and Thin Ionic Liquid Interface for Highly Sensitive and Rapid Detection of Hydrogen.

Hydrogen has been widely used in industrial and commercial applications as a carbon-free, efficient energy source. Due to the high flammability and explosion risk of hydrogen-air mixtures, it is vital to develop sensors featuring fast-responding and high sensitivity for hydrogen leakage detection. This paper presents a miniaturized electrochemical gas sensor by elaborately establishing a nanocomposite and thin ionic liquid interface for highly sensitive and rapid electrochemical detection of hydrogen, in which a remarkable response time and recovery time of approximately 6 s was achieved at room temperature. A screen-printed carbon electrode was modified with a reduced graphene oxide-carbon nanotube (rGO-CNT) hybrid and platinum-palladium (Pt-Pd) bimetallic nanoparticles to realize high sensitivity. To achieve miniaturization and high stability of the sensor, a thin-film room-temperature ionic liquid (RTIL) was employed as the electrolyte with a significantly decreased response time. The fast-responding hydrogen sensor demonstrates excellent performance with high sensitivity, linearity, and repeatability at concentrations below the lower explosive limit of 4 vol %. The engineered high-performance interface and gas sensor provide a promising and effective strategy for gas sensor design and rapid hazardous gas monitoring.

Simultaneous Detection of Citric Acid and Oxalic Acid Based on Dual Spectrum and Biomimetic Peroxidase for Urolithiasis Screening with a Fully Automatic Urine Analyzer.

Urolithiasis stands as a prevalent ailment within the urinary system, with hyperoxaluria and hypocitraturia being the most frequent manifestations characterized by excessive oxalic acid (OA) and deficient citric acid (CA) levels in urine. Detecting these compounds in urine quantitatively holds paramount importance for early urolithiasis screening. Existing methodologies fall short in achieving simultaneous and on-site identification of OA and CA, posing challenges for accurate urolithiasis screening. Addressing this concern, the study successfully accomplishes the concurrent identification of OA and CA in urine through a combination of dual-spectral analysis and biomimetic peroxidase utilization. Bovine serum albumin and dithiothreitol-modified copper nanoclusters (BSA-DTT-CuNCs) are employed as biomimetic peroxidases, effectively mitigating interference and enabling the simultaneous determination of OA and CA. The quantification range spans from 0 to 12 mm for OA and 0.5 to 2.5 mm for CA, with detection limits of 0.18 and 0.11 mm, respectively. To facilitate swift and on-location urine analysis, a fully automated urine analyzer (FAUA) is introduced that streamlines the process of biomarker pretreatment and identification within urine samples. Validation with real urine samples from urolithiasis patients demonstrates the method's diagnostic precision, highlighting the dual-spectral technique and analyzer's promising role in urolithiasis screening.

Radical Acylfluoroalkylation of 1,3-Enynes via N-Heterocyclic Carbene/Photoredox Cooperative Catalysis.

We report a novel three-component radical acylfluoroalkylation of 1,3-enynes by synergistic N-heterocyclic carbene (NHC)/photoredox catalysis toward various fluorinated allenic aryl ketones. This protocol features a broad substrate scope and excellent functional group tolerability, with examples of late-stage modification of drug molecules and natural products. Notably, seven different fluoroalkyl motifs can be introduced to 1,3-enynes, further demonstrating the robustness and generality of this method. The generation of the fluoroalkyl radical from each sulfinate reagent was individually supported by EPR experiments.

Engineering a universal and fully automatic analyzer for multichannel and on-site biochemical detection in body fluids.

OBJECTIVE: Rising concerns over wellness and aging have heightened the demand for convenient and efficient on-site health monitoring and disease screening. Current research, focused on specific biomarker detection, often neglects the complexities of sample matrix interference and the absence of a comprehensive, automated platform. To address these issues, we have developed a universal, fully automated analyzer for multifaceted, on-site biochemical analysis of body fluids. METHODS: This analyzer integrates automated sample pretreatment, automatic dilution, detection, and self-cleaning functionalities seamlessly. It is designed to detect a wide range of analytes, from small molecules to macromolecules, including ions and proteins, utilizing spectrophotometric sensing. After optimization, the analyzer achieves performance comparable to traditional Enzyme-Linked Immunosorbent Assay (ELISA), while significantly expanding its detection range through automated dilution. RESULTS: Demonstrations of small molecule detection include the simultaneous assessment of citric acid (CA) and oxalic acid (OA) in urine, achieving recovery rates between 96.65%-106.42% and 93.13%-112.50%, respectively. For protein detection, the analyzer successfully identified Cyfra21-1 in saliva with a recovery rate of 104.93%-111.31%. The pre-treatment process requires only 8.8 minutes, showing enhanced recovery rates for CA and OA at 97.8% and 97.6% respectively, which are superior and more rapid than manual methods. CONCLUSION: The exemplary pretreatment and detection performance of the analyzer underlines its effectiveness in multifaceted, on-site biomarker detection, establishing it as a promising and versatile tool for disease screening and health monitoring. SIGNIFICANCE: This analyzer offers a powerful technological solution for on-site fluid testing, advancing community health care by facilitating more reliable and rapid diagnostics.

Dynamic microphysiological system chip platform for high-throughput, customizable, and multi-dimensional drug screening.

Spheroids and organoids have attracted significant attention as innovative models for disease modeling and drug screening. By employing diverse types of spheroids or organoids, it is feasible to establish microphysiological systems that enhance the precision of disease modeling and offer more dependable and comprehensive drug screening. High-throughput microphysiological systems that support optional, parallel testing of multiple drugs have promising applications in personalized medical treatment and drug research. However, establishing such a system is highly challenging and requires a multidisciplinary approach. This study introduces a dynamic Microphysiological System Chip Platform (MSCP) with multiple functional microstructures that encompass the mentioned advantages. We developed a high-throughput lung cancer spheroids model and an intestine-liver-heart-lung cancer microphysiological system for conducting parallel testing on four anti-lung cancer drugs, demonstrating the feasibility of the MSCP. This microphysiological system combines microscale and macroscale biomimetics to enable a comprehensive assessment of drug efficacy and side effects. Moreover, the microphysiological system enables evaluation of the real pharmacological effect of drug molecules reaching the target lesion after absorption by normal organs through fluid-based physiological communication. The MSCP could serves as a valuable platform for microphysiological system research, making significant contributions to disease modeling, drug development, and personalized medical treatment.

A light-addressable potentiometric sensor-based extracellular calcium dynamic monitoring and imaging platform for cellular calcium channel drug evaluation.

Disruption and dysregulation of cellular calcium channel function can lead to diseases such as ischemic stroke, heart failure, and arrhythmias. Corresponding calcium channel drugs typically require preliminary efficacy evaluations using in vitro models such as cells and simulated tissues before clinical testing. However, traditional detection and evaluation methods often encounter challenges in long-term continuous monitoring and lack calcium specificity. In this study, a dynamic monitoring system based on ion-sensitive membranes for light-addressable potentiometric sensor (LAPS) was developed to meet the demand for monitoring changes in extracellular calcium ion (Ca2+) concentration in live cells. The effects of Ca2+ channel agonists and blockers on 2D and 3D HL-1 cells were investigated, with changes in extracellular Ca2+ concentration reflecting cellular calcium metabolism, facilitating drug evaluation. Additionally, calcium imaging technology with optical addressing capability complemented the LAPS system's ability to perceive 3D cell morphology, enhancing its drug evaluation capabilities. This work provides a novel, label-free, specific, and stable technique for monitoring cellular calcium metabolism. It achieves both continuous monitoring at single points and custom sensing area calcium imaging, holding significant implications for drug screening and disease treatment related to human calcium homeostasis.

Corrigendum: Ti4O7/g-C3N4 visible light photocatalytic performance on hypophosphite oxidation: Effect of annealing temperature.

[This corrects the article DOI: 10.3389/fchem.2018.00037.].

Organocatalytic Three-Component Acyldifluoromethylation of Vinylarenes via N-Heterocyclic Carbene-Catalyzed Radical Relay.

We herein describe an N-hetercyclic carbene-catalyzed three-component acyldifluoromethylation of vinylarenes, aldehydes, and NaSO2CF2H. This organocatalytic approach provides a practical route for the synthesis of pharmaceutically relevant α-aryl-ß-difluormethyl ketones without the need for transition metals or photocatalysts. The late-stage acyldifluoromethylation of drug analogues was also demonstrated. The reaction design employs NaSO2CF2H as the source of the CF2H radical in the presence of an oxidant for the radical relay.

The degradation of printing and dyeing wastewater by manganese-based catalysts.

Printing and dyeing wastewater generally has high pH, high turbidity, poor biodegradability, complex composition, and high chroma, which make it one of the most difficult industrial wastewaters to treat. Herein, heterogeneous ozone oxidation technology is applied to oxidize and degrade printing and dyeing wastewater. A metal oxide catalyst supported on activated carbon (γ-MnO2/AC) was prepared by hydrothermal synthetic method and shown to enable synergistic catalysis involving MnO2 metal sites and N/C sites. A simulated methyl orange solution was used to determine the effects of various preparation and operation parameters. The results confirmed that the γ-MnO2/AC catalyst exhibited good chemical oxygen demand (COD) removal and reusability. Additionally, γ-MnO2/AC demonstrated excellent degradation of the secondary biochemical effluent of printing and dyeing wastewater (COD removal = 72.45% within 120 min). The γ-MnO2/AC catalyst was fully characterized, and the mechanism governing its catalytic ozone oxidation process was investigated experimentally.

Capacitative deionization using commercial activated carbon fiber decorated with polyaniline.

Capacitive deionization (CDI) has become a promising technology for water desalination due to its remarkable advantages including low operation cost, no secondary pollution and high rate of ion recovery. However, the majority of commercial CDI electrode materials are carbonaceous materials such as activated carbon with limited capacitance and high charge transfer resistance, which significantly hinders the wide application of CDI. Herein, we demonstrate a N-doped carbonaceous CDI electrode with a maximum ion electrosorption capacity of 19.9 mg/g, a low charge transfer resistance (1.17 Ω) and a robust regeneration performance (2800 min for 28 circles). The N-doped carbonaceous CDI electrode is the commercial activated carbon fiber (ACF) decorated with polyaniline (PANI) (ACF/PANI) electrode fabricated by in-situ electrochemical polymerization. The ACF/PANI electrode was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The pseudocapacitance of ACF/PANI electrode significantly contributed to the effectively improved CDI performance that 90.0% of sodium storage was attributed to the capacitive process and the unique porous structure of ACF/PANI electrode contributed to the other 10.0% diffusion-controlled capacity.

Ti4O7/g-C3N4 for Visible Light Photocatalytic Oxidation of Hypophosphite: Effect of Mass Ratio of Ti4O7/g-C3N4.

Hypophosphite wastewater treatment is still a critical issue in metallurgical processes and the oxidation of hypophosphite to phosphate followed by the precipitation of phosphate is an important strategy for hypophosphite wastewater treatment. Herein, Ti4O7/g-C3N4 photocatalysts with various mass ratios (Ti4O7 (m): g-C3N4 (m) = 0.5, 0.2, 0.1, and 0.05) were synthesized by a hydrolysis method and the effect of the mass ratio of Ti4O7 (m): g-C3N4 (m) on Ti4O7/g-C3N4 visible light photocatalytic oxidation of hypophosphite was evaluated. The as-prepared Ti4O7/g-C3N4 were characterized and confirmed by SEM, XPS, XRD and FTIR. Moreover, the specific surface area and the distribution of pore size of Ti4O7/g-C3N4 was also analyzed. Our results showed that Ti4O7/g-C3N4 exhibited remarkably improved photocatalytic performance on hypophosphite oxidation compared with g-C3N4 and meanwhile 1:2-Ti4O7/g-C3N4 with a mass ratio of 0.5 showed the best photocatalytic performance with the highest oxidation rate constant (17.7-fold and 91.0-fold higher than that of pure g-C3N4 and Ti4O7, respectively). The enhanced performance of photocatalytic oxidation of hypophosphite was ascribed to the heterojunction structure of Ti4O7/g-C3N4 with broader light absorption and significantly enhanced efficiency of the charge carrier (e--h+) generation and separation. Additionally, the generated ·OH and · O2- radicals contributed to the hypophosphite oxidation during the photocatalytic system.

An electrochemical method through hydroxyl radicals oxidation and deposition of ferric phosphate for hypophosphite recovery.

Phosphorus is an essential and irreplaceable element of the ecosystem. In this work, phosphorus has been recovered using an electro-Fenton process. The effects of current intensity, initial pH and H2O2 concentration on the recovery of hypophosphite were investigated. When the current intensity, pH value, and H2O2 concentration were 0.2 A, 3.0 and 90 mM, respectively, hypophosphite was completely oxidized to phosphate. Under such conditions, the phosphate was recovered through the generation of deposition. In order to determine the mechanism of hypophosphite recovery, the morphology and microstructure of the deposition were analyzed using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, high resolution transmission electron microscopy, Fourier transform infrared and X-ray photoelectron spectra. The generation of hydroxyl radicals was confirmed using electron spin resonance technique. This method is a clean process for phosphorus recovery, and does not generate hazardous substances.

Ti4O7/g-C3N4 Visible Light Photocatalytic Performance on Hypophosphite Oxidation: Effect of Annealing Temperature.

The oxidation of hypophosphite to phosphate is the key to recover the phosphorus resource from the hypophosphite wastewater. In the present work, Ti4O7/g-C3N4 composites were synthesized at two different temperatures (100 and 160°C) and their performance on photocatalytic oxidation of hypophosphite under visible light irradiation and the corresponding mechanism were evaluated. A hydrolysis method using g-C3N4 and Ti4O7 was applied to synthesize the Ti4O7/g-C3N4 composites with their hybrid structure and morphology confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectra (XPS). The annealing temperature significantly affected the photocatalytic performance of Ti4O7/g-C3N4 that the 160-Ti4O7/g-C3N4 composite (fabricated at 160°C) showed the highest oxidation efficiency of hypophosphite of 81% and the highest photocatalytic oxidation rate of 0.467 h-1 comparing with the 100-Ti4O7/g-C3N4 composite (fabricated at 100°C) and pure g-C3N4. The enhanced photocatalytic performance of 160-Ti4O7/g-C3N4 could be ascribed to the effective charge separation and enhanced photoabsorption efficiency. Additionally, electron spin resonance (ESR) results showed that hydroxyl radicals and superoxide anion radicals were mainly responsible to the oxidation of hypophosphite with superoxide anion radicals accounting for a more significant contribution. Moreover, Ti4O7/g-C3N4 photocatalysts showed the remarkable stability in the repetitive experiments.

[Oxidation Destruction of Cu(CN)32- by Persulfate].

In recent years, cyanide contamination problem is becoming more and more serious. Cyanides widely occur in the wastewater from metallurgical industry and electroplating industry. The efficiency for cyanides removal of conventional physical and chemical methods is not very satisfactory. Therefore, it is urgent to develop highly efficient and environmental friendly methods for the removal of cyanides. As an environmental-friendly oxidant, potassium persulfate is widely used in the treatment of organic pollutants. The destruction of Cu(CN)32- was investigated by homogeneous K2S2O8 under alkaline conditions, and the reaction mechanism was analyzed. The effects of the amount of K2S2O8 and the ratio of Cu+/CN- on the degradation of CN- were studied. With the increase of K2S2O8 dose, the rate of CN-oxidation was accelerated. The removal efficiency of CN- reached 89.6% after 60 min of reaction in the presence of 2 mmol·L-1 K2S2O8. Oxidation of CN- was accelerated with Cu+/CN- increasing from 2.0 to 5.0. Cu+ was oxidized to Cu2+ and copper oxide was formed during the reaction. The reactive radicals were analyzed using electron spin resonance and radical quenching experiments, and the results indicated that both radicals oxidation pathway and non-radical oxidation pathway were responsible for the removal of Cu(CN)32- by K2S2O8.

Cyanide oxidation by singlet oxygen generated via reaction between H2O2 from cathodic reduction and OCl(-) from anodic oxidation.

Cyanide is widely present in electroplating wastewater or metallurgical effluents. In the present study, the electrochemical destruction of cyanide with various anode and cathode compositions under alkaline conditions was investigated. The results indicated that the electrochemical system using RuO2/Ti as anode and activated carbon fiber (ACF) as cathode in the presence of sodium chloride was efficient for the cyanide removal. In this system, in situ generation of HClO by anodic oxidation of Cl(-) at RuO2/Ti anode occurred with the H2O2 generation by O2 reduction at ACF cathode. As confirmed by the electron spin resonance technique, the reaction between HClO and H2O2 led to the generation of singlet oxygen, which was responsible for the cyanide removal. Further experiment indicated that the cyanide removal efficiency increased with the increase of the current density or the sodium chloride concentration. Cyanate was identified as main product in the system. Besides, the system exhibited good stability for the cyanide removal, which was beneficial to its practical application.