Multipath collaboration-based signal amplification on Z-scheme In2O3/g-C3N4 heterojunction photoelectrode for sensitive photoelectrochemical immunoassay.

The ideal photoelectrode and efficient signaling strategy are pivotal to achieve sensitive photoelectrochemical (PEC) analysis. Here, a multipath collaborative signal amplification-based PEC immunosensor was constructed for the ultrasensitive detection of cytokeratin 19 fragment 21-1. Specifically, the photoelectrode fabricated by Z-scheme In2O3/g-C3N4 heterojunction showed enhanced photocurrent intensity in response to visible light. Meanwhile, the signal probe, horseradish peroxidase functionalized dopamine-melanin nanosphere@Au nanoparticles (HRP-Dpa-melanin NS@AuNPs), were introduced into the system. When the target exists, the signal probe can induce multiple quenching of the photocurrent due to the competition of light absorption, steric hindrance and HRP-mediated biocatalytic precipitation, which effectively inhibit light, electron donor, and electron access to the photoelectrode. The fabricated immunosensor exhibits a wide linear range from 1.0 × 10-3 - 1.0 × 102 ng mL-1 with the detection limit of 0.35 pg mL-1 (S/N = 3) for cytokeratin 19 fragment 21-1 detection. The study enhances sensitivity for PEC detection by utilizing the superior Z-scheme heterojunction photoelectrode, providing a valuable method that combines multiple signal pathways for a synergistic effect in bioanalysis.

Smartphone-assisted detection of trace methyl orange in water by ratiometric nanosensors based on down/up-conversion luminescence.

A ratiometric nanosensor was developed for detecting methyl orange (MO) based on down/up-conversion luminescence achieved by a triplet-triplet annihilation upconversion luminescence (TTA-UCL) system. The probe, utilizing sensitizer and annihilator fluorophores encapsulated in nanomicelles, demonstrated high sensitivity and selectivity for MO detection. The energy transfer from UCL to MO endowed the sensor with responsive capabilities. The unaffected triplet-triplet energy transfer process maintained the phosphorescence signal constant, serving as a reference to construct the ratiometric sensor along with the UCL signal. Additionally, a smartphone-assisted colorimetric detection method was also developed based on the ratiometric sensor, enabling rapid and convenient detection of MO without the need for a spectrometer. The performance of the nanosensor in real water samples confirmed its potential for practical environmental applications.

Low blue-hazard white-light emission based on color-tunable triplet-triplet annihilation upconversion.

The commonly used artificial light sources, such as fluorescent lamps and white light-emitting diodes, often have a high ratio of blue light emission, which poses potential blue light hazards, especially one of the main culprits leading to eye diseases. Therefore, developing novel white lighting sources with low blue-hazard is highly appreciated. In this work, an air-stable and color-tunable triplet-triplet annihilation upconversion (TTA-UC) mechanism was proposed to realize the low blue-hazard white-light emission. The proposed design was composed of three primary RGB colors from the annihilator (9,10-diphenylanthracene, DPA), the laser excitation source, and the photosensitizer (palladium (II) octaetylporphyrin, PdOEP), respectively. The introduction of oil-in-water (o/w) microemulsion can effectively block the potential oxygen-induced triplet-quenching and benefit high UC efficiency. Moreover, either raising ambient temperatures or adding isobutanol can activate the UC process to yield white-light emission. Notably, the white-light emission with a Commission Internationale de l'Eclairage (CIE) coordinate of (0.33, 0.33) as well as a low ratio of blue emission (14.2 %) was achieved at an ambient temperature of 42 °C. Therefore, the proposed air-stable TTA-UC mechanism can significantly lower the blue-hazard and provide a novel solution for applications in lighting and display.

Solvothermal synthesis of PdCu nanorings with high catalytic performance for alcohol electrooxidation.

Two-dimensional (2D) Pd-based nanostructures with a high active surface area and a large number of active sites are commonly used in alcohol oxidation research, whereas the less explored ring structure made of nanosheets with large pores is of interest. In this study, we detail the fabrication of PdCu nanorings (NRs) featuring hollow interiors and low coordinated sites using a straightforward solvothermal approach. Due to increased exposure of active sites and the synergistic effects of bimetallics, the PdCu NRs exhibited superior catalytic performance in both the ethanol oxidation reaction (EOR) and the ethylene glycol oxidation reaction (EGOR). The mass activities of PdCu NRs for EOR and EGOR were measured at 7.05 A/mg and 8.12 A/mg, respectively, surpassing those of commercial Pd/C. Furthermore, the PdCu NRs demonstrated enhanced catalytic stability, maintaining higher mass activity levels compared to other catalysts during stability testing. This research offers valuable insights for the development of efficient catalysts for alcohol oxidation.

Ir Doping Modulates the Electronic Structure of Flower-Shaped Phosphides for Water Oxidation.

Electrolysis of water to produce hydrogen is an efficient, clean, and environmentally friendly hydrogen production method with unlimited development prospects. However, its overall efficiency is hampered by the slow oxygen evolution reaction (OER) with complex electron transfer processes. Therefore, designing efficient and low-cost OER catalysts is the key to solving this problem. In this paper, Ir-doped Co2P/Fe2P (abbreviated as Ir-CoFeP/NF) was grown on nickel foam through the strategies of low amount noble-metal doping and mild phosphating. Phosphide derived from a floral metal-organic framework (MOF) exhibits regular three-dimensional (3D) morphology and large active area, avoiding the stacking of active sites. The addition of Ir can effectively adjust the electronic structure, change the position of the d-band center, and increase active sites, thus enhancing the catalytic activity. Hence, the optimized catalyst exhibits unexpected electrocatalytic OER activity with an ideal overpotential of 213 mV at 10 mA cm-2, as well as a low Tafel slope of 40.63 mV dec-1. Coupling with Pt/C for overall water splitting (OWS), the entire device only needs an ultralow cell voltage of 1.50 V to achieve a current density of 10 mA cm-2. Besides, the OWS can be maintained for more than 70 h. This study demonstrates the superiority of Ir-doped phosphide in accelerating water oxidation.

SnO2@PdAg Core-Shell Nanoarchitecture Promotes Active and Stable Alcohol Electrooxidations.

Developing efficient Pd-based electrocatalysts is of vital importance for the application of direct alcohol fuel cells. Designing the core-shell architecture of Pd-based nanomaterials rationally has emerged as an effective strategy to promote the sluggish kinetics of anodic reactions. Herein, the PdAg alloy is reduced on a non-noble metal oxide surface for the formation of a core-shell nanostructure. The optimized SnO2@PdAgh nanospheres deliver the optimal catalytic performance compared with other counterparts and commercial Pd/C. The structural investigation reveals that the introduction of Ag and formation of a PdAg/SnO2 heterointerface effectively regulate the electronic structure of Pd, making SnO2@PdAgh a highly active catalyst for methanol and ethylene glycol oxidation reactions. Impressively, the strong interaction between the PdAg shell and SnO2 core stabilizes the metal-oxide heterointerface, contributing to the improved stability of SnO2@PdAgh in electrocatalytic reactions. This study proposes the use of non-noble metal oxides as the core to suppress the dissolution of the catalysts and highlights the rational design of core@shell nanoarchitectures.

Study on Dynamic Liquid-Carrying Process of Foaming Agent and Establishment of Mathematical Model.

The efficiency of foam drainage gas recovery is predominantly dictated by the performance of the foaming agent. To better understand their behavior, a novel testing apparatus was developed to simulate the foam drainage gas recovery process within the wellbore. Through the dynamic liquid-carrying performance tests of four foaming agents under uniform conditions, it was discerned that there existed significant disparities in the liquid-carrying performance and action duration. Further interface performance analysis disclosed that the liquid-carrying capacity and the duration were correlated with their adsorption capacity and interface activity at the gas-liquid interface. Notably, foaming agents with lower adsorption capacity and higher interfacial activity demonstrated superior liquid-carrying performance and longer action duration. By analyzing the consumption of foaming agents during the liquid-carrying process, five dynamic liquid-carrying equations were derived based on first-order reaction kinetics, the Malthusian population model, and the logistic function. The outcomes demonstrated that all these five equations could precisely delineate the dynamic liquid-carrying process of the foaming agent. During the research, we found that the consumption of the foaming agent in the foam drainage gas recovery process is related to its adsorption behavior at the gas-liquid interface, and revealed that the dynamic liquid-carrying process of foaming agent is the increasing process of liquid-carrying capacity under the continuous consumption of limited foaming agent resources. This laid a foundation for the further exploration of the functional mechanism of the foaming agent in the foam drainage gas recovery process.

Saltwater intrusion of the Nandu River under the changing environment in China.

Saltwater problems in the Nandu River have gradually intensified in recent years. The effect of runoff variability (RV) on saltwater intrusion has not yet been fully revealed. Long-term trends in runoff and sea level (SL) were analyzed using the Mann-Kendall test and Theil-Sen estimation, and salinity exceedance rates (Ps) were calculated based on MIKE 11 and daily runoff distributions. As RV increased, Ps decreased the most at 16.0 km (6.7 %) and increased the most at 23.2 km (5.3 %). SL increased by 0.4 m and Ps increased the most at 20.5 km (11.7 %). Constant Ps is projected to move downstream by the 2060s and 210 s, with maximum increases in Ps of 6.2 % and 10.1 %, respectively. The ratio of changes in Ps due to changes in RV and SL is about 0.85. Constant Ps sections can be used to assess the risk of saline intrusion in some of the world's estuaries.

Dye-sensitized lanthanide-doped upconversion nanoprobe for enhanced sensitive detection of Fe3+ in human serum and tap water.

Iron ion (Fe3+) detection is crucial for human health since it plays a crucial role in many physiological activities. In this work, a novel Schiff-base functionalized cyanine derivative (CyPy) was synthesized, which was successfully assembled on the surface of upconversion nanoparticles (UCNPs) through an amphiphilic polymer encapsulation method. In the as-designed nanoprobe, CyPy, a recognizer of Fe3+, is served as energy donor and ß-NaYF4:Yb,Er upconversion nanoparticles are adopted as energy acceptor. As a result, a 93-fold enhancement of upconversion luminescence is achieved. The efficient energy transfer from CyPy to ß-NaYF4:Yb,Er endows the nanoprobe a high sensitivity for Fe3+ in water with a low detection limit of 0.21 µM. Moreover, the nanoprobe has been successfully applied for Fe3+ determination in human serum and tap water samples with recovery ranges of 95 %-105 % and 97 %-106 %, respectively. Moreover, their relative standard deviations are all below 3.72 %. This work provides a sensitive and efficient methodology for Fe3+ detection in clinical and environmental testing.

Application of visual intelligent labels in the assessment of meat freshness.

With the increasing demand for meat products, the evaluation and real-time monitoring of its freshness has become one of the focuses of related industry research. Conventional freshness detection methods, including sensory evaluation, microbial experiments, and determination of physicochemical indicators, are time-consuming, low sensitivity, and destructive, so there is an urgent need to develop a convenient, intuitive, and inexpensive detection method. As a representative of smart packaging, visual intelligent labels can realize real-time perception and monitoring of meat freshness by measuring the temperature, pH value or other indicators of meat and converting them into visual signals. This paper first summarizes the common types, basic principles and research progress of visual intelligent labels, then introduces its application in livestock, poultry and seafood freshness monitoring, finally looks forward to the development prospect of visual smart labels.

Programmable multimode optical encryption of advanced printable security inks by integrating structural color with Down/Up- conversion photoluminescence.

Optical information encryption with high encoding capacities can significantly boost the security level of anti-counterfeiting in the scenario of guaranteeing the authenticity of a wide scope of common and luxury goods. In this work, a novel counterfeiting material with high-degree complexity is fabricated by microencapsulating cholesteric liquid crystals and triplet-triplet annihilation upconversion fluorophores to integrate structural coloration with fluorescence and upconversion photoluminescence. Moreover, the multimode security ink presents tailorable optical behaviors and programmable abilities on flexible substrates by various printing techniques, which offers distinct information encryption under different optical modes. The advanced strategy provides a practical versatile platform for high-secure-level multimode optical inks with largely enhanced encoding capacities, programmability, printability, and cost-effectiveness, which manifests enormous potentials for information encryption and anti-counterfeiting technology.

Recent Advances in DNA Nanotechnology-Based Sensing Platforms for Rapid Virus Detection.

Several major viral pandemics in history have significantly impacted the public health of human beings. The COVID-19 pandemic has further underscored the critical need for early detection and screening of infected individuals. However, current detection techniques are confronted with deficiencies in sensitivity and accuracy, restricting the capability of detecting trace amounts of viruses in human bodies and in the environments. The advent of DNA nanotechnology has opened up a feasible solution for rapid and sensitive virus determination. By harnessing the designability and addressability of DNA nanostructures, a range of rapid virus sensing platforms have been proposed. This review overviewed the recent progress, application, and prospect of DNA nanotechnology-based rapid virus detection platforms. Furthermore, the challenges and developmental prospects in this field were discussed.

Harnessing Heavy-Atom Effects in Multiple Resonance Thermally Activated Delayed Fluorescence (MR-TADF) Sensitizers: Unlocking High-Performance Visible-to-Ultraviolet (Vis-to-UV) Triplet Fusion Upconversion.

Ultraviolet (UV) light plays a crucial role in various applications, but currently, the efficiency of generating artificial UV light is low. The visible-to-ultraviolet (Vis-to-UV) system based on the triplet-triplet annihilation upconversion (TTA-UC) mechanism can be a viable solution. Metal-free multiple resonance thermally activated delayed fluorescence (MR-TADF) materials are ideal photosensitizers (PSs) apart from the drawback of high photoluminescence quantum yields (PLQYs). Herein, we systematically investigated the impact of the heavy-atom effect (HAE) on the MR-TADF sensitizers. BNCzBr was then synthesized by incorporating a bromine atom into the skeleton of the precursor BNCz. Impressively, the internal HAE (iHAE) leads to a significantly decreased PLQY and a remarkably increased intersystem crossing quantum yield (ΦISC). Consequently, a higher upconversion quantum efficiency of 12.5% was realized. While the external HAE (eHAE) harms the UC performance. This work guides the further development of MR-TADF sensitizers for high-performance Vis-to-UV TTA-UC systems.

Carbon doping enhances the fluoride removal performance of aluminum-based adsorbents.

Excessive fluoride presence in water poses significant environmental and public health risks, necessitating the development of effective remediation techniques. Conventional aluminum-based adsorbents face inherent limitations such as limited pH range and low adsorption capacity. To overcome these challenges, we present a facile solvent-thermal method for synthesizing a carbon-doped aluminum-based adsorbent (CDAA). Extensive characterization of CDAA reveals remarkable features including substantial carbon-containing groups, unsaturated aluminum sites, and a high pH at point of zero charge (pHpzc). CDAA demonstrates superior efficiency and selectivity in removing fluoride contaminants, surpassing other adsorbents. It exhibits exceptional adaptability across a broad pH spectrum from 3 to 12, with a maximum adsorption capacity of 637.4 mg/g, more than 110 times higher than alumina. The applicability of the Langmuir isotherm and pseudo-second-order models effectively supports these findings. Notably, CDAA exhibits rapid kinetics, achieving near-equilibrium within just 5 min. Comprehensive analyses utilizing Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) offer detailed insights into the mechanisms involving electrostatic attraction, ion exchange, and ligand exchange. Carbon-based groups play a role in ligand exchange processes, synergistically interacting with the unsaturated aluminum structure to provide a multitude of adsorption sites. The exceptional attributes of CDAA establish its immense potential as a transformative solution for the pressing challenge of fluoride removal from water sources.

An AIEE-active Triphenylethylene Derivative with Photoresponsive Character for Latent Fingerprints Detection via a Simple Soaking Method.

Latent fingerprints (LFPs) is one of the most important physical evidence in the criminal scene, playing an important role in forensic investigations. Therefore, developing highly sensitive and convenient materials for the visualization of LFPs is of great significance. We designed and synthesized an organic fluorescent molecule TP-PH with aggregation-induced enhanced emission (AIEE) activity. By simply soaking, blue fluorescent images with high contrast and resolution are readily developed on various surfaces including tinfoil, steel, glass and plastic. Remarkably, LFPs can be visualized within 5 min including the first-, second- and tertiary-level details. In addition, TP-PH exhibits interesting photoactivated fluorescence enhancement properties. Under irradiation of 365 nm UV light with a power density of 382 mW/cm2, the fluorescence quantum yield displays approximately 21.5-fold enhancement. Mechanism studies reveals that the photoactivated fluorescence is attributed to the irreversible cyclodehydrogenation reactions under UV irradiation. This work provides a guideline for the design of multifunctional AIEE fluorescent materials.

Regio- and Diastereoselective Radical Dimerization Reactions for the Construction of Benzo[f]isoindole Dimers.

This study presents a novel approach for synthesizing benzo[f]isoindole dimers, which involves cascade cyclization and oxidative radical dimerization. Our method allows for the formation of up to five carbon-carbon bonds in a single reaction, exhibiting remarkable diastereoselectivity and regioselectivity. The mechanism and regioselectivity were investigated through a combination of experiments and calculations.

STM/TERS observation of (M)-type diphenyl[7]thiaheterohelicene on Ag(111).

The chiral recognition of a self-assembled structure of enantiopure (M)-type 2,13-diphenyl[7]thiaheterohelicene ((M)-Ph-[7]TH) was investigated on a Ag(111) substrate by scanning tunnelling microscopy (STM) and tip-enhanced Raman spectroscopy (TERS). In contrast to previous research of thiaheterohelicene and its derivatives showing zigzag row formation on the Ag(111) substrate, the hexagonal ordered structure was observed by STM. The obtained TERS spectra of (M)-Ph-[7]TH were consistent with the Raman spectra calculated on the basis of density functional theory (DFT), which suggests that (M)-Ph-[7]TH was adsorbed on the substrate without decomposition. The sample bias voltage dependence of STM images combined with the calculated molecular orbitals of (M)-Ph-[7]TH indicates that a phenyl ring was observed as a protrusion at +3.0 V, whereas the helicene backbone was observed at +0.5 V. From these results, a possible model of the hexagonal structure was proposed. Owing to the phenyl ring, the van der Waals interaction between (M)-Ph-[7]TH and the substrate becomes strong. This leads to the formation of the hexagonal structure with the same symmetry as the substrate.

Synthesis of a new fluorophore: wavelength-tunable bisbenzo[f]isoindolylidenes.

The creation of new functional molecules is a central task in chemical synthesis. Herein, we report the synthesis of a new type of fluorophore, bisbenzo[f]isoindolylidenes, from easily accessible dipropargyl benzenesulfonamides. Wavelength-tunable fluorophores emitting strong fluorescence of green to red light were obtained in this reaction. Late-stage modifications and incorporation of bioactive molecules into these fluorophores give rise to potential applications in biological studies. Detailed computational and experimental studies were conducted to elucidate the mechanism, and suggest a reaction sequence involving Garratt-Braverman type cyclization, isomerization, fragmentation, dimerization and oxidation.

Enhancing fluoride removal from wastewater using Al/Y amended sludge biochar.

This study explored the potential of utilizing aluminum and yttrium amended (Al/Y amended) sewage sludge biochar (Al/Y-CSBC) for efficient fluoride removal from wastewater. The adsorption kinetics of fluoride on bimetallic modified Al/Y-CSBC followed the pseudo-second-order model, while the adsorption isotherm conformed to the Freundlich equation. Remarkably, the material exhibited excellent fluoride removal performance over a wide pH range, achieving a maximum adsorption capacity of 62.44 mg·g-1. Moreover, Al/Y-CSBC demonstrated exceptional reusability, maintaining 95% removal efficiency even after six regeneration cycles. The fluoride adsorption mechanism involved ion exchange, surface complexation, and electrostatic adsorption interactions. The activation and modification processes significantly increased the specific surface area of Al/Y-CSBC, leading to a high isoelectric point (pHpzc = 9.14). The incorporation of aluminum and yttrium metals exhibited a novel approach, enhancing the adsorption capacity for fluoride ions due to their strong affinity. Furthermore, the dispersing effect of biochar played a crucial role in improving defluoridation efficiency by enhancing accessibility to active sites. These findings substantiate the significant potential of Al/Y-CSBC for enhanced fluoride removal from wastewater.

Photochemically deoxygenating micelles for protecting TTA-UC against oxygen quenching.

Pluronic F127, P123 and cross-linked F127 diacrylate micelles are photochemically deoxygenating nanocapsules in which oxygen could be removed by photochemical reaction with a surfactant and efficient triplet-triplet annihilation photon upconversion (TTA-UC) can be achieved in air. The efficiency of TTA-UC under air is comparable to that under deoxygenated conditions.