化学•材料最新文献

We extend the diffraction calculations made by Spindeler [(2017), PhD thesis, Bielefeld University] and Gohlke [(2017), Master's thesis, Bielefeld University] to a family of two-dimensional constant-shape random substitutions and a nonconstant-shaped example. Specifically, we consider a family of binary constant-shape random block substitutions of size k × k defined by the rule vartheta:b mapsto a^{ktimes k}, a mapsto {vartheta^{(i)}(a) with probability p_{1}mid 1leq ileq N-1}, where kin{bb N}, p_i > 0 for all 0 ≤ i ≤ N - 1 and sum_{i = 0}^{N-1}p_{i} = 1 with a^k×k and each ϑ_i(a) is a square block of size k × k. We illustrate that their corresponding systems have a mixed spectral type consisting of a pure-point part and a continuous part that is only fully absolutely continuous. We also explore extending the computation to random Fibonacci direct product variation, presenting a heuristic diffraction framework for the class of nonconstant-shape but geometrically compatible inflation rules.

Nitrogen-containing compounds are ubiquitous in pharmaceuticals, agrochemicals, and functional materials, and the development of sustainable methodologies for carbon-nitrogen (C─N) bond formation is of fundamental importance. Herein, we report a rationally designed bifunctional ligand and micellar cooperativity that effectively enables Cu-catalyzed amination of aryl bromides under mild aqueous conditions. A series of structurally tailored ligands was designed by systematically tuning their electronic and steric properties to stabilize the active copper catalyst and promote selective C─N bond formation. When combined with the bio-derived non-ionic surfactant CNSL-1000-M, the micellar environment provides a confined hydrophobic reaction space, enhancing catalyst performance and substrate activation. This cooperative ligand-micelle system enables the C─N coupling with both electron-rich and electron-deficient aryl bromides at 60°C, affording the corresponding aryl amines in good to excellent yields. The active Cu catalyst was thoroughly characterized by UV-visible spectroscopy, x-ray photoelectron spectroscopy (XPS), and Electron Paramagnetic Resonance (EPR). It is worth noting that our current catalyst system shows better catalytic activity and selectivity than conventional organic solvents such as DMF, 1,4-dioxane, DMSO, and toluene. This study demonstrates that electronic, steric, and micellar cooperativity play decisive roles in aqueous copper-catalyzed reactions and establishes a practical, sustainable platform for C─N cross-coupling reactions.

Electrochemical aptamer-based (E-AB) microneedle (MN) sensors offer a promising route for continuous monitoring of endogenous biomarkers. However, long-term operation is often limited by signal attenuation arising from surface biofouling, aptamer detachment, and redox label degradation. Here, we investigated the origin of signal drift by monitoring changes in the peak current (I_P) of the redox label during prolonged square-wave voltammetry (SWV) operation in PBS, serum, and artificial ISF. To address this drift, we introduced a dual-frequency ratiometric approach based on the ratio between the I_P measured at frequencies showing maximum (F_max) and minimum (F_min) responses. Prolonged SWV measurements in PBS, where biofouling is negligible, showed a gradual decrease in I_P, and cyclic voltammetry measurements obtained before and after SWV operation confirmed a decrease in the MB faradaic current. These results suggest that SWV-induced aptamer detachment and/or MB degradation are major source of intrinsic signal drift. In serum and artificial ISF, this drift was further exacerbated by biofouling, resulting in an approximately 30% decrease in I_P measured at F_max and F_min (IF_max and IF_min) over 48 h. In contrast, the ratiometric signal (I_R = IF_max/IF_min), remained stable because similar signal drift in IF_max and IF_min was effectively compensated. In addition, the ratiometric approach reduced sensor-to-sensor variation, enabling reliable continuous cortisol monitoring with quantified concentrations that closely matched the applied levels, whereas IF_max-based quantification resulted in large deviations. These findings establish dual-frequency ratiometric E-AB MN sensors as a reliable platform for stable and accurate continuous biomarker monitoring in complex biological fluids.

Metal complexes are emerging as powerful agents in light-activated cancer therapy, a cutting-edge therapeutic strategy for combating cancer and other serious diseases. Among them, iridium (Ir)-based photosensitizers have recently gained significant attention, driving innovation in photo-activated cancer therapy and opening new avenues for targeted treatment. Building on this momentum, we have designed a novel benzimidazole-based iridium complex, [LIr], which demonstrates remarkable potential as a phototherapeutic agent. Upon activation with a direct light source from a 40 W white LED (400-700 nm), with a fixed distance of 15 cm between the light source and the samples maintained throughout all the experiments, [LIr] exhibits potent catalytic activity, efficiently oxidizing key cellular antioxidants: converting glutathione (GSH) to glutathione disulfide (GSSG), NADH to NAD⁺, and NADPH to NADP⁺. This redox disruption compromises cancer cell defenses and enhances therapeutic efficacy. In addition, light activation of complex [LIr] generates a burst of reactive oxygen species (ROS), including the highly cytotoxic singlet oxygen, with a notable singlet oxygen quantum yield. This multifaceted reactivity not only disrupts cellular redox balance but also induces oxidative stress in targeted cancer cells.

Catalytic hydroboration of N-heteroarenes and imines represents an attractive and sustainable strategy for accessing a broad range of synthetically valuable nitrogen-containing compounds. Herein, we disclose the metal-free catalytic activity of bicyclic (alkyl)(amino)carbene (BICAAC) (I) toward the hydroboration of N-heteroarenes and imines using pinacolborane (HBpin). The catalyst exhibits excellent regioselectivity, promoting 1,4-hydroboration of pyridines and 1,2-hydroboration of quinolines, while efficiently reducing a variety of imines under mild reaction conditions. Mechanistic investigations, based on a series of control experiments, reveal that the reaction is initiated by the addition of the B─H bond of HBpin across the carbene center to generate the catalytically active BICAAC-borane species (II). This intermediate activates the substrate through a Lewis acid-base interaction between the boron center and the nitrogen atom of the substrate, followed by hydride transfer from a second equivalent of HBpin to afford the hydroborated products. This work significantly expands the scope of BICAAC organocatalysis and demonstrates its potential as an efficient metal-free catalyst for the reduction of challenging nitrogen-containing unsaturated substrates.

The global rise in waterborne viral infections has created an urgent need for portable, highly efficient environmental virus detection technologies. CRISPR-based nucleic acid detection coupled with isothermal amplification (e.g., Recombinase Polymerase Amplification, RPA) shows great promise for field applications. However, most reported designs fail to achieve the single-molecule sensitivity, which significantly limits their practical applications. To bridge the gap, we proposed a rational design strategy for the RPA primer and the CRISPR-Cas13a crRNA, suggesting that sensitivity can be enhanced by simplifying the secondary structure of the crRNA spacer region. Subsequently, we established a portable, one-tube CRISPR-Cas13a bioassay to detect two major waterborne viruses, achieving ultrasensitive detection limits of 5/8 aM for norovirus and 2/3 aM for rotavirus within 40 min. Thereafter, seasonal sampling across different treatment stages of a drinking water treatment plant was conducted, and water samples were analyzed using the one-tube CRISPR-Cas13a bioassay in comparison with qPCR and dPCR, revealing a positive detection rate of 15.79% (6/38) for the one-tube CRISPR-Cas13a bioassay, 18.42% (7/38) for qPCR, and 15.79% (6/38) for dPCR. The assay's modular design allows for broad applicability to other pathogens by simply modifying the target nucleic acid sequence, offering high sensitivity and specificity. This innovation paves the way for deployable point-of-care testing and large-scale spatiotemporal virus monitoring.

This research addresses the challenge of real-time monitoring of the neurotransmitter serotonin (5-HT), a key chemical messenger in the brain whose dynamics are important for understanding neurological disorders. While electrochemical methods are promising for such real-time detection, existing approaches face limitations in maintaining stable performance in physiological settings and achieving precise spatiotemporal measurements. To overcome these barriers, two electrochemical systems were developed: one for monitoring 5-HT secretion from cells and another for tracking 5-HT in the mouse brain. By enhancing electrodes with specific nanocomposites to improve sensitivity and selectivity, the cell system successfully analyzed real-time 5-HT secretion dynamics from rat insulinoma cells with performance comparable to standard methods. The neural interface system effectively tracked 5-HT fluctuations across multiple brain regions in living mice and detected changes induced by external interventions. These platforms enable real-time tracking of 5-HT dynamics both in cells and in living organisms, demonstrating significant potential for studies requiring real-time neurotransmitter monitoring.

A symbolic random substitution assigns to each letter a finite set of possible images with a probability distribution producing complex dynamical systems with positive entropy, mixed spectral types and nuanced mixing properties. In this study, we consider a two-dimensional random substitution where each letter is mapped to a finite set of a nonempty array of letters called rectangular words, such that any letter can be iterated infinitely many times via canonical concatenation to produce larger and larger rectangular words. We show that such systems are topologically transitive, have either empty or dense sets of periodic points, and have dense sets of linearly repetitive elements. For the case of a primitive block random substitution subshift, we show that its inflation block entropy coincides with its topological entropy.

The Wigner function provides a complete phase-space representation of a quantum state. Yet, direct experimental access to such a quantity for electrons in crystalline solids remains an elusive goal. Here, we report the first reconstruction of an experimental one-electron Wigner function in a molecular crystal. By jointly refining an ensemble N-representable model against high-resolution X-ray diffraction structure factors and directional Compton profiles, we reconstruct a 6D phase-space distribution consistent with both position- and momentum-space data. The reconstructed Wigner function exhibits pronounced negative regions that provide a direct indication of the non-classical nature of the electronic state and shows remarkable agreement with correlated post-Hartree-Fock calculations. Our results demonstrate that complementary scattering experiments can be unified within a single phase-space tomography approach, opening a route towards experimentally reconstructed electron quantum states in crystalline materials.