Langmuir最新文献

Although chirality is critical for molecular properties and functions, experimental quantification of chirality is lacking. Herein, we performed cyclic voltammetry (CV) under polarized magnetic fields to provide a unified scale to quantify and compare DNA chirality. We observed the largest electron spin polarization in DNA structures with opposite chiral senses, which is consistent with the effect of chiral-induced spin selectivity (CISS). Spin polarization is weaker among DNA topologies of the same chiral arrangement, with DNA triplexes exhibiting the strongest CISS. Within DNA duplexes, spin polarization is further reduced depending on the sequence, with fewer guanine-cytosine (GC) pairs displaying a weaker CISS likely due to localized variations in chirality. Surprisingly, spin polarization is vectorial along the DNA duplex while presenting the smallest variation when the transportation directions of electrons become opposite. The four factors, chiral sense, topology, sequence, and directionality of electron transportation, delineate hierarchical contributions to molecular chirality, with profound implications ranging from spintronics to molecular recognitions.

The homogeneity and stability of the structure of anodic TiO₂ nanotube (ATNT) arrays have been a hot topic in materials synthesis research. In this work, the current density distribution during the anodization of ATNT arrays was optimized by adding polyethylene glycol-600 (PEG-600) to the conventional ethylene glycol-based electrolyte, which enhanced the dependence of the electronic current on the applied voltage, thus providing a stabilizing effect on anodization and improving the homogeneity of the pores on the surface of ATNT arrays. A new image processing approach, called the region-growing method, is reported in this work, which can quantitatively analyze the pore size of ATNT arrays through SEM images, and the surface morphology of ATNT arrays was evaluated based on this. The most stable anodization was obtained with a 50 wt % PEG-600 addition, and the equivalent diameters of the pores prepared at applied voltages of 40, 50, and 60 V were 34.5340, 42.4010, and 50.4791 nm, respectively, with a linear correlation of 0.9999.

Ru/NC shows a good catalytic performance in cellobiose-to-sorbitol hydrogenation. However, the molecular origins of the selective orientation of the reaction pathway remain unclear. Here, we rationally designed the Ru₂/NC catalyst, for which Ru2@N8 V4 is preferred as the model. The hydrogenation mechanisms for the hydrogenation of β-cellobiose to sorbitol employing H₂ as the H-source in aqueous solution have been investigated over Ru2@N8 V4 at the GGA-PBE/DNP level. For the hydrogenation of β-cellobiose to sorbitol, the optimal reaction pathway involves the ring-opening of cellobiose with H₂O as a promoter and then the hydroreduction of aldehyde group, followed by the β-1,4-glycosidic bond hydrolysis. The selective orientation of the optimal reaction pathway originates from the dissociation of H₂O on Ru-sites of Ru2@N8 V4 to form Brønsted acid (Ru-H⁺) and Brønsted base (Ru-OH^-), which collaboratively promote the ring-opening. The rate-determining steps are relative to the β-1,4-glycosidic bond cleavage, where an applicable π-π interaction between reactant molecule and Ru2@N8 V4 is of critical importance. Kinetically, the β-1,4-glycosidic bond cleavage from cellubitol is more favorable than that from β-cellobiose. For the hydrogenation of β-cellobiose to cellubitol, the first ring-opening with H₂O as promoter and then hydrogenation are kinetically superior to the direct hydrogenation and ring opening. This derives from its dissociation over Ru-sites to Ru-H and Ru-OH groups. Predictably, protic solvents (HOR) are readily dissociated into Ru-H and Ru-OR at Ru-sites, which can promote the ring-opening of pyran-ring. The present research outcomes should contribute to the theoretical understanding necessary for the development of novel supported noble metal N-doped carbon catalysts for the hydrogenation of cellulose.

Understanding the formation of highly ordered structures through self-assembly is crucial for developing various biologically relevant systems. A significant expansion in the development of self-assembly chemistry features stable coassembly formation using a mixture of two oppositely charged polymers. This study provides insightful findings on the coassembly of hydrophobic coumarin-integrated cationic (P1-P3) and anionic (P1'-P3') copolymers toward the formation of vesicles in aqueous medium at pH 7.4, with a hydrodynamic diameter (D_h) of 160 ± 10 nm and electrically neutral zwitterionic surfaces, confirmed by dynamic light scattering. Upon varying the solution pH, an intriguing charge switchable behavior (+ve → 0 → -ve) and a drastic morphological transition to spherical aggregates of the vesicles were noticed. At pH 7.4, these coassembled vesicles possess a neutral surface charge, empowering them to resist nonspecific protein (pepsin and lysozyme) adsorption via electrostatic repulsion, as evidenced by size evolution and protein binding measurements. Additionally, the bilayer membrane allows for the encapsulation of hydrophilic and hydrophobic guest molecules and their sustained release in the presence of 10 mM esterase; thus, this study demonstrates potential applications of coassembly to serve as a drug delivery vehicle.

Synthesizing catalyst supports with appropriate compositions and structures is crucial for reducing the sizes of metal nanoparticles and enhancing their catalytic activities. In this work, a series of monolithic hyper-cross-linked supports (HCP-CC) with hierarchical pores were synthesized. The monolithic structure facilitated easy operation in catalytic reactions, while the composition and structure of HCP-CC could be tailored simultaneously by utilizing the functional cross-linking agent cyanogen chloride. Furthermore, in situ loading of nano-Ag into HCP-CC resulted in the hybrid catalyst HCP-CC-Ag. The synergy of confinement and coordination effect controlled and limited the size of nano-Ag to approximately 3 nm, classifying them as ultrasmall nanoparticles, which ensured outstanding catalytic activity. This hybrid catalyst could improve the reaction rate constant to 0.423 min^-1; it efficiently promoted the degradation of organic dye and exhibited great universality and recyclability, making it a potential heterogeneous catalyst for dye wastewater treatment.

This study presents a simple approach for fabricating low-density drug-polymer amorphous solid dispersions (ASDs) using a piezoelectric inkjet method, demonstrating potential applications for floating drug delivery systems (FDDS). By adjusting the ratio of two polymers, polylactic acid, and Eudragit RLPO, the floatability and drug release rate of the drug-polymer ASD particles can be easily manipulated. Kinetic model analyses have been conducted to interpret the drug release mechanism. This work offers a robust platform for exploring diverse polymer-drug combinations that are applicable to FDDS.

We investigate herein the impact of helical structures on the motion of asymmetrical droplets along vertically twisted fibers. The droplet adopts helical motion around the bundle driven by gravity. This complex motion can be manipulated by varying the twists turns of the fibers. When the droplet size is smaller than the characteristic length of the helix (pitch), the droplet adopts a predominant helical motion correlated to the groove of the twisted fibers. When the droplet size exceeds the pitch length, a mixed motion of intermittent vertical sliding and helical movement emerges. A model describes rotational and linear speeds as a function of the number of fiber twist turns. This research highlights the profound role of substructures in droplet dynamics, offering fresh insight into droplet manipulation or fiber-based devices.

Covalent organic frameworks (COFs) possessing a well-defined structure and abundant functional groups are prospective pseudocapacitive electrode materials. However, their intrinsic poor electrical conductivity and stacking problems usually impede the utilization of their active sites. Herein, we conduct an in situ growth of polyimide COFs (donated as NTDA COFs) enriched with carbonyl groups on multiwalled carbon nanotubes (MWCNTs). An impressive capacitance of 467 F g^-1 at 1 A g^-1 is achieved for the as-prepared NTDA/MWCNTs composite, significantly surpassing both the pure MWCNTs (60.3 F g^-1) and NTDA COFs (284.4 F g^-1). No decay of capacitance is observed after 10,000 cycles at 10 A g^-1. The assembled device NTDA/MWCNTs//activated carbon reaches a high energy density of 17 Wh kg^-1 at 750 W kg^-1 while keeping superior charging/discharging stability of 89.5% after cycling for 19,000 times at 10 A g^-1. In situ Fourier transform infrared (in situ FT-IR) tests together with the exploration of electrode kinetics show that the boosted capacitance of NTDA/MWCNTs is mainly donated by the redox reactions of carbonyl groups on NTDA COFs, which is largely activated by MWCNTs.

Sodium manganese hexacyanoferrate, also called Prussian white (PW), has attracted much attention as a promising cathode material for Na-ion batteries due to its high-voltage platform and inexpensive elemental composition. However, their parasitic vacancies and water molecules often deteriorate the electrochemical performance. Proper regulation of such defects in scale-up preparation is still a challenge. In this work, PW was prepared via aqueous precipitation assisted by manganese oxalate in a 10 L reactor. High-quality Na_2.32Mn[Fe(CN)₆]_0.95□_0.05·1.97 H₂O was obtained and exhibited a specific capacity of 148 mAh g^-1. The phase transition from monoclinic to rhombohedral during long-term cycling for such an ultra-Na-rich cathode has been first reported. In addition, the vacuum drying temperature was further discussed, and 150 °C is more suitable for achieving the balance between dehydration and electrical properties.

Amino-functionalized silica has attracted a great deal of interest due to its high surface reactivity and potential for diverse applications across various fields. While the classical co-condensation method is commonly used to synthesize amino-functionalized silica particles, the mechanism of the reaction between (3-aminopropyl)triethoxysilane (APTES) and tetraethoxysilane under different conditions remains unclear, leading to unexpected self-nucleation or cross-linking between silica particles and consequently hindering rational control over the extent of functionalization. To address this issue, we systematically explored the co-condensation growth mechanism of amino-functionalized silica particles in the Stöber method by investigating the effects of APTES concentration and water content on the hydrolysis and condensation of silanes. The experimental results revealed that APTES could decrease the rate of hydrolysis/condensation, while the moderate water content promoted both the rate of hydrolysis/condensation and the overall quality of the silica particles. Consequently, we successfully demonstrated the rational synthesis of amino-functionalized silica particles with diameters ranging from 213 to 670 nm and a nitrogen content of ≤2.8 wt %. The relationship between the APTES concentration and particle properties exhibited a biphasic trend. At low APTES concentrations (≤2.0 mM), the particle size remained stable while the isoelectric point increased rapidly. Further increasing the APTES concentration from 2.0 to 100.0 mM induced a decrease in particle size due to APTES's inhibitory effect on silica growth, with nitrogen content continuing to increase even after the isoelectric point remained unchanged. These silica particles, featuring varying surface amino group densities, were utilized as matrices for loading Au nanoparticles. The resulting functionalized particles exhibited distinctive catalytic ability in the reduction of 4-nitroaniline, demonstrating significant potential for applications across various fields.