A Turn-On Fluorescent Sensor for Sensitive and Selective Detection of Sodium Dodecyl Sulfate Based on the Eosin Y/Polyethyleneimine System

A novel sensing system has been designed for the detection of sodium dodecyl sulfate (SDS) based on the recovered fluorescence signal of eosin Y and polyethyleneimine (PEI) complex. The eosin Y reacted with PEI to form a complex by virtue of hydrophobic interaction as well as the electrostatic interaction, which resulted in a strong fluorescence quenching of the eosin Y. Subsequently, with the addition of SDS to the eosin Y/PEI system, a strong surface interaction and electrostatic interactions between PEI and SDS resulted in the formation of the PEI/SDS complex and the dissociation of the eosin Y/PEI complex, which led to the significant fluorescence recovery. Herein, we have demonstrated that this facile methodology can offer a rapid, reliable, and selective detection of SDS with a detection limit as low as 0.02 μg mL^–1 and a linear range from 0.4 to 6 μg mL^–1. Furthermore, the method has been successfully applied to the detection of SDS in real samples with satisfied recovery and accuracy. Overall, these results demonstrate that this method has great promise for environmental applications

Luminescent Electrophoretic Particles via Miniemulsion Polymerization for Night-Vision Electrophoretic Displays

A novel glowing electrophoretic display (EPD) is achieved by luminescent electrophoretic particles (EPs), which is potentially to improve the situation in which the existing EPDs disable in darkness. To combine both modes of reflective and emissive displays, a trilayer luminescence EP is designed and synthesized via an improved miniemulsion polymerization. The luminescence EP is composed of a pigment core, a polystyrene interlayer, and a fluorescent coating. The particle sizes are from 140 to 170 nm, and the size distribution is narrow. Their ζ potential value is −12.4 mV, which is enough to migrate in the electrophoretic fluid by the driving of an electric field. The display performance of the particles in an EPD cell has been characterized under the bias of 20 V. Both the reflectance (491 nm) and fluorescence (521 nm) intensities of the EPD cell remained in a constant range after 30 switches

Rewritable Pressure-Driven <i>n</i>–<i>p</i> Conduction Switching in Marcasite-Type CrSb₂

Temperature- or pressure-driven n–p conduction-type switching has been described as an emerging phenomenon for potential applications as transistors, switches, and memory devices. The key challenge in the development of such n–p conduction-type switching materials is to establish maneuverable and controllable methods to achieve easy convertibility and nonvolatility. Herein, we report the first example of rewritable pressure and temperature dual-controlled n–p conduction-type switching in marcasite-type CrSb2. At room temperature, CrSb2 exhibits an unexcepted pressure-driven n–p conductivity-type switching around 12 GPa accompanied by a marcasite-to-arsenopyrite structural transition and a semiconductor-to-metal transition. The dramatic conduction-type switching is irreversible after pressure releasing at room temperature but reversible by annealing at a relatively low temperature (>80 °C). Accordingly, a multicycle bistability switching process is established under the dual regulation of both pressure and temperature. The underlying structure–property mechanism is revealed by in situ/ex situ characterization and analyses of the atomic-level microstructure, local lattice distortion, and residual stress induced by compression. This demonstration provides a new platform for the rational design of rewritable temperature/pressure-responsive photoelectric conversion devices

Pressure-Induced Phase Transformation, Reversible Amorphization, and Anomalous Visible Light Response in Organolead Bromide Perovskite

Hydrostatic pressure, as an alternative of chemical pressure to tune the crystal structure and physical properties, is a significant technique for novel function material design and fundamental research. In this article, we report the phase stability and visible light response of the organolead bromide perovskite, CH₃NH₃PbBr₃ (MAPbBr₃), under hydrostatic pressure up to 34 GPa at room temperature. Two phase transformations below 2 GPa (from <i>Pm</i>3̅<i>m</i> to <i>Im</i>3̅, then to <i>Pnma</i>) and a reversible amorphization starting from about 2 GPa were observed, which could be attributed to the tilting of PbBr₆ octahedra and destroying of long-range ordering of MA cations, respectively. The visible light response of MAPbBr₃ to pressure was studied by in situ photoluminescence, electric resistance, photocurrent measurements and first-principle simulations. The anomalous band gap evolution during compression with red-shift followed by blue-shift is explained by the competition between compression effect and pressure-induced amorphization. Along with the amorphization process accomplished around 25 GPa, the resistance increased by 5 orders of magnitude while the system still maintains its semiconductor characteristics and considerable response to the visible light irradiation. Our results not only show that hydrostatic pressure may provide an applicable tool for the organohalide perovskites based photovoltaic device functioning as switcher or controller, but also shed light on the exploration of more amorphous organometal composites as potential light absorber

Superconductivity in Quasi-One-Dimensional Ferromagnet CrSbSe₃ under High Pressure

Nearly a decade has passed since the discovery of superconductivity in CrAs, but until now, the discovered structure types of chromium-based superconductors are still scanty. It is urgent to expand this family to decipher the interplay between magnetism and superconductivity penetratingly. Here, we report the observation of superconductivity in ferromagnet CrSbSe3 with a quasi-one-dimensional structure under high pressure. Under compression, CrSbSe3 undergoes an insulator-to-metal transition and sequential isostructural phase transitions accompanied by volume collapse. Superconductivity emerges at 32.8 GPa concomitant with metallization in CrSbSe3. A maximum superconducting transition temperature Tc of 7.7 K is achieved at 57.9 GPa benefiting from both the phonon softening and the enhanced p–d hybridization between Se and Cr in CrSbSe3. The discovery of superconductivity in CrSbSe3 expands the existing chromium-based superconductor family and sheds light on the search for concealed superconductivity in low-dimensional van der Waals materials

Iron-Doped Carbon Nitride-Type Polymers as Homogeneous Organocatalysts for Visible Light-Driven Hydrogen Evolution

Graphitic carbon nitrides have appeared as a new type of photocatalyst for water splitting, but their broader and more practical applications are oftentimes hindered by the insolubility or difficult dispersion of the material in solvents. We herein prepared novel two-dimensional (2D) carbon nitride-type polymers doped by iron under a mild one-pot method through preorganizing formamide and citric acid precursors into supramolecular structures, which eventually polycondensed into a homogeneous organocatalyst for highly efficient visible light-driven hydrogen evolution with a rate of ∼16.2 mmol g^–1 h^–1 and a quantum efficiency of 0.8%. Laser photolysis and electrochemical impedance spectroscopic measurements suggested that iron-doping enabled strong electron coupling between the metal and the carbon nitride and formed unique electronic structures favoring electron mobilization along the 2D nanomaterial plane, which might facilitate the electron transfer process in the photocatalytic system and lead to efficient H₂ evolution. In combination with electrochemical measurements, the electron transfer dynamics during water reduction were depicted, and the earth-abundant Fe-based catalyst may open a sustainable strategy for conversion of sunlight into hydrogen energy and cope with current challenging energy issues worldwide

Low-Temperature Fluorination Route to Lanthanide-Doped Monoclinic ScOF Host Material for Tunable and Nearly Single Band Up-Conversion Luminescence

Lanthanide upconversion (UC) materials that convert near-infrared excitations into visible emissions are of extensive current interest owing to their potential applications in biosensing, 3D displays, and solar cells. A wise choice of the host lattice is crucial for high-quality UC luminescence with desired emission wavelengths. From the viewpoint of structural chemistry, here we propose monoclinic scandium oxyfluoride (M-ScOF) as a promising UC host material for the following reasons: (1) the shortest Sc³⁺–Sc³⁺ distance (3.234 Å, versus 3.584 Å of Y³⁺–Y³⁺ in hexagonal NaYF₄); (2) the unique crystallographic site of Sc in the structure; (3) specific coordination environment of Sc with 4O + 3F in <i>C</i>₁ symmetry. Lanthanide doping in an individual host with such structural features is highly expected to achieve single band emission and fast energy migration for high-efficiency UC process. Experimentally, we employ a low temperature fluorination method to synthesize pure and lanthanides doped M-ScOF samples successfully by using polytetrafluoroethylene as the fluridizer. The Yb³⁺/Ho³⁺-codoped M-ScOF nanoparticles exhibit tunable UC emissions with various red/green ratios under excitation of λ_ex = 980 nm. Nearly single-band red (∼660 nm) and near-infrared (∼805 nm) UC luminescence have been achieved in Yb³⁺/Er³⁺- and Yb³⁺/Tm³⁺-incorporated samples, respectively. We believe that more attention to M-ScOF and the search for other advanced host materials based on structural chemistry perspective will greatly boost the development of high-efficiency UC phosphors in various applications such as bioprobes and chromatic displays

Capillary blood for point-of-care testing

<p>Clinically, blood sample analysis has been widely used for health monitoring. In hospitals, arterial and venous blood are utilized to detect various disease biomarkers. However, collection methods are invasive, painful, may result in injury and contamination, and skilled workers are required, making these methods unsuitable for use in a resource-limited setting. In contrast, capillary blood is easily collected by a minimally invasive procedure and has excellent potential for use in point-of-care (POC) health monitoring. In this review, we first discuss the differences among arterial blood, venous blood, and capillary blood in terms of the puncture sites, components, sample volume, collection methods, and application areas. Additionally, we review the most recent advances in capillary blood-based commercial products and microfluidic instruments for various applications. We also compare the accuracy of microfluidic-based testing with that of laboratory-based testing for capillary blood-based disease diagnosis at the POC. Finally, we discuss the challenges and future perspectives for developing capillary blood-based POC instruments.</p

Polydimethylsiloxane-Paper Hybrid Lateral Flow Assay for Highly Sensitive Point-of-Care Nucleic Acid Testing

In nucleic acid testing (NAT), gold nanoparticle (AuNP)-based lateral flow assays (LFAs) have received significant attention due to their cost-effectiveness, rapidity, and the ability to produce a simple colorimetric readout. However, the poor sensitivity of AuNP-based LFAs limits its widespread applications. Even though various efforts have been made to improve the assay sensitivity, most methods are inappropriate for integration into LFA for sample-to-answer NAT at the point-of-care (POC), usually due to the complicated fabrication processes or incompatible chemicals used. To address this, we propose a novel strategy of integrating a simple fluidic control strategy into LFA. The strategy involves incorporating a piece of paper-based shunt and a polydimethylsiloxane (PDMS) barrier to the strip to achieve optimum fluidic delays for LFA signal enhancement, resulting in 10-fold signal enhancement over unmodified LFA. The phenomena of fluidic delay were also evaluated by mathematical simulation, through which we found the movement of fluid throughout the shunt and the tortuosity effects in the presence of PDMS barrier, which significantly affect the detection sensitivity. To demonstrate the potential of integrating this strategy into a LFA with sample-in-answer-out capability, we further applied this strategy into our prototype sample-to-answer LFA to sensitively detect the Hepatitis B virus (HBV) in clinical blood samples. The proposed strategy offers great potential for highly sensitive detection of various targets for wide application in the near future