Stacking Effect Research Articles

Lateral intercalation-assisted ionic transport towards high-performance organic electrochemical transistor

Efficiently mixed conduction between ionic and electronic charges stands to revolutionize the studies in organic electrochemical transistors (OECTs). However, inefficient ion transport due to the long-range injection and migration process in the bulk film presents challenges for enhancing the steady and transient performance of OECTs. In this work, we proposed a lateral intercalation-assisted ion transport strategy to assist volumetric ion charging, by introducing a striped microstructure in the conductive channel. By precisely adjusting the ratio of lateral area (RoL), the electrical performance, indicated by the maximum transconductance versus response time (Gm,max/τ), increases progressively by over 600%. We further unveiled the mechanism for the enhanced doping uniformity and increased volume capacitance at the lateral area. Based on the universality investigation, we uncovered the effects of molecular stacking on ionic lateral intercalation transport, contributing to the high-performance OECTs and the bio-applications in the recording of dynamic electrocardiography (ECG) signals with distinct features.

Maresin-1 Ameliorates Sepsis-Induced Microglial Activation Through Modulation of the P38 MAPK Pathway.

Sepsis is a life-threatening disease characterized by a dysregulated immune response to infection, often leading to neuroinflammation. As a known immunomodulator, Maresin-1 (MaR1) may have potential applications in the treatment of sepsis-induced neuroinflammation, but its effects in this context are unknown. We used a mouse cecum ligation and puncture (CLP)-induced sepsis model and an in vitro lipopolysaccharide (LPS)-induced neuroinflammatory model of BV2 microglia. Expression of microglial cell markers (IBA1, CD11B, CD68, CD86 and CD206) and pro-inflammatory markers (iNOS and COX2) was assessed. The role of MaR1 in regulating the P38 MAPK pathway was explored using the P38 MAPK inhibitor SB203580. In the CLP model, an increased proportion of M1-type microglia was observed, and MaR1 was able to reverse it. However, the combination of SB203580 and MaR1 did not enhance the therapeutic effect compared to SB20580 alone. In vitro experiments, MaR1 inhibited LPS-induced P38 MAPK nuclear translocation and decreased the expression of pro-inflammatory markers such as iNOS and COX2. As with the animal results, no stacking effect could be obtained with the co-administration of SB203580 and MaR1. Our findings suggest that MaR1 attenuates sepsis-induced neuroinflammation mainly by inhibiting phosphorylation of P38 MAPK in microglial cells. This suggests that MaR1 may have a potential therapeutic role in the treatment of sepsis neuroinflammation.

Highly Sensitive Solid Ratiometric Luminescent Thermometer Based on N,C-Chelating Four-Coordinate Organoboron Compounds.

Realizing ratiometric thermometers using single-component organic solid-state luminophores is attractive but challenging. Here, we synthesized a series of N,C-chelated tetra-coordinated organoboron compounds and characterized their structures. Among them, sample BN2Br can be used as a luminescent thermometer and exhibits a high temperature sensitivity (3.67% K-1), a wide response range of 120-280 K, and good reversibility, which is mainly due to the temperature-dependent intermolecular stacking effect in the solid state. The proposed ratiometric thermometry protocol may provide new insights for developing photonic thermometers.

Fabrication of MOF-on-MOF composites by surfactant-assisted growth strategy for SPME of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants with strong carcinogenicity and mutagenicity, which cause great harm to the environment and food. Herein, a composite (NH2-MIL-88@PCN-224) was prepared through a guest PCN-224 in situ grown on the host NH2-MIL-88 by a surfactant-assisted growth strategy, and successfully applied for solid-phase microextraction (SPME) of PAHs from milk samples. The prepared SPME coatings exhibited high extraction and adsorption capacity for PAHs due to their porous structure, ultra-large specific surface area, strong π-π stacking, hydrophobic interactions and size-matching effects. The SPME-GC-FID method based on NH2-MIL-88@PCN-224 coated fibers has the significant advantages of wide linear range (1–200 ng mL−1), low detection limit (0.003–0.020 ng mL−1), high recoveries (92.15–106.64 %) and good reproducibility. This work overcomes the lattice-matching limitation by adopting a surfactant-assisted growth strategy, which offers a new direction for the preparation of ultra-high-performance SPME coatings with extremely high extraction efficiency, exceptional thermal stability, and long service life, and greatly expands the variety of MOF SPME coatings.

First-principles study on a new 2D carbon allotrope with an intrinsic wide bandgap: A comparison with α-graphyne

Nanocarbon materials with intrinsic electronic bandgaps are highly desirable for next-generation carbon-based nanoelectronics. Herein, a new two-dimensional (2D) carbon allotrope with structural similarities to α-graphyne has been proposed theoretically, which exhibits intrinsic semiconducting behavior with a wide direct bandgap significantly larger than that reported in other 2D carbon allotropes. Based on first-principles calculations, the structural and electronic properties of the new 2D carbon allotrope, as well as its lattice stability, have been systematically investigated by adopting a comparative study with α-graphyne. Moreover, the effects of vertical stacking and in-plane biaxial strain on the new 2D carbon allotrope have also been clarified in this work, providing robust approaches for the effective modulation of electronic properties in the new 2D carbon allotrope. Thus, the intrinsic wide bandgap, along with effective modulations, suggests great advantages and potentials of the new 2D carbon allotrope in carbon-based electronic devices and light-emitting applications.

CO2 Fixation via epoxide cycloaddition with a highly active and stable MOF-808/GO composite catalyst

The CO2 cycloaddition reaction effectively mitigates the greenhouse effect while producing high-value cyclic carbonates. Metal-organic frameworks (MOFs) have shown promise for CO2 cycloaddition with epoxides; however, the aggregation of MOFs due to high surface energy hinders mass transfer and catalytic performance. By pre-coordinating graphene oxide (GO) to regulate the dispersion of MOF-808, the resulting MOF-808/GO-100 composite catalyst exhibits twice the activity of pristine MOF-808, achieving 92.6% conversion of epichlorohydrin (ECH) with 98.2% selectivity to ECH carbonate without adding any co-catalysts. The incorporation of GO introduces numerous hydroxyl groups on the catalyst surface, serving as hydrogen bonding donors. The oxygen-containing groups on GO can compete with ligands for Zr coordination, generating defective Zr sites. The synergistic effect between defective Zr sites and hydrogen bonding donors collectively promotes epoxide opening. Notably, GO correspondingly enhances the dispersion of MOF-808 and induces mesopore formation through its stacking effect at the interface with MOF-808. Across various epoxide cycloaddition reactions, MOF-808/GO-100 consistently demonstrated optimal performance and maintained high stability over multiple reaction cycles.

Optical and stress properties of ZrO2/SiO2 and TiO2/SiO2 anti-reflective coatings deposited by ion-beam-assisted deposition on a flexible substrate

Dielectric films of ZrO2,TiO2, and SiO2 were deposited on flexible polycarbonate (PC) and polyethylene terephthalate (PET) substrates by using ion-beam-assisted deposition (IBAD). Each layer had a thickness ranging from 30 to 210 nm. The optical and anisotropic stress properties were investigated. Two anti-reflective coatings (ARCs), ZrO2/SiO2 and TiO2/SiO2, were selected and deposited on the PET flexible substrate. The anisotropic stresses of the single layer and ARCs were measured using a phase-shifting moiré interferometer. Experimental results showed that the optimal oxygen flow rates for the ZrO2,TiO2, and SiO2 films deposited with IBAD were 10, 10, and 15 sccm, respectively. The refractive index (n) was TiO2(2.37)>ZrO2(2.05)>SiO2(1.46), and the extinction coefficient (k) for all samples was below 10−3. The thermal expansion coefficient of the PC substrate was three times that of the PET substrate, and the high-refraction ZrO2 and TiO2 single-layer films presented cracks and distortions on the PC substrate. Only the low-refractive-index SiO2 sample did not present cracks. The three dielectric films did not crack or distort when deposited on the PET substrate. The anisotropic stress analysis provided the maximum principal and shear stresses for the three dielectric films on the PET substrate. Therefore, the maximum principal stress of the 210 nm single-layer film on a PET substrate is TiO2>ZrO2>SiO2. It was also discovered that the principal stress of the AR multilayer film is significantly decreased due to the damping stacking effect (DSE) of the high- and low-refractive-index materials, ZrO2/SiO2 ARC (−297.3MPa)>TiO2/SiO2ARC(−132.6MPa). Thus, the high packing density of TiO2 gives a better DSE than ZrO2.

Ultralow Potential Cathodic Electrochemiluminescence Aptasensor for Detection of Kanamycin Using Copper Nanoribbons as Coreaction Accelerator.

An ultralow cathodic potential electrochemiluminescence (ECL) aptasensor was designed, employing DNA nanoribbon template self-assembly copper nanoclusters (DNR-CuNCs) as a novel coreaction accelerator within the luminol-H2O2 system for the sensitive detection of kanamycin (KANA). Mechanistic investigations revealed that the DNR-CuNCs preferred to generate highly active hydroxyl radicals by facilitating the reduction of the coreactant H2O2 under neutral pH conditions, consequently enhancing cathodic luminescence. By the strong π-π stacking effect of KANA aptamer and graphene as a signal modulation switch, DNR-CuNCs were displaced from the electrode surface due to the affinity of KANA and its aptamer, resulting in the inhibition of the luminol-H2O2 system and a decrease in the ECL signal. Under optimal experiments, the aptasensor demonstrated exceptional sensitivity in detecting KANA within the concentration range from 1 × 10-2 to 5 × 105 pg/mL, with the detection limit as low as 0.18 fg/mL. This innovative strategy provided a novel approach to designing effective ECL emitters for monitoring food safety.

Copper-coordinated nanomedicine for the concurrent treatment of lung cancer through the induction of cuproptosis and apoptosis

The resistance of tumor cells to apoptosis often leads to chemoresistance and treatment failure in clinic. In this study, we have developed a Cu2+-coordinated lignosulfonate (CLS) /doxorubicin (DOX) biological complex (referred to as LCD) with the aim of overcoming cellular resistance to apoptosis for combined lung cancer therapy. The copper complexes modified by CLS exhibit significant water solubility and excellent in vivo biocompatibility. The proportion of copper in the composite is simultaneously increased. Due to the coordination and π-π stacking effects, the self-assembled LCD exhibits nanometer-scale particle size, a narrow and homogeneous grain distribution, as well as excellent dispersion stability. Furthermore, LCD has the potential to disassemble in the presence of high levels of glutathione (GSH) and low pH, leading to effective drug release. Cu2+-mediated cuproptosis can lead to the down-regulation of FDX1 and DLAT protein expression by reducing mitochondrial membrane potential, resulting in non-apoptotic programmed cell death (PCD) regardless of cellular resistance to apoptosis. Moreover, the released DOX not only exhibits a preference for localizing in the cell nucleus to induce apoptosis for combined chemotherapy, but also generates a substantial amount of H2O2. This H2O2 further produces ROS to induce apoptosis through Fenton reaction with Cu2+. LCD demonstrates significant superiority over monotherapy in inhibiting tumor growth while minimizing systemic toxicity through the combined action of cuproptosis and apoptosis. This study may provide a potential avenue for the advancement of self-delivery nanomedicine to overcome resistance to apoptosis in tumor therapy.

Reinforcement and Controlling the Stability of Poly(ε-caprolactone)-Based Polymeric Materials via Reversible and Movable Cross-Links Employing Cyclic Polyphenylene Sulfide.

Due to its biodegradation ability, poly(ε-caprolactone) (PCL) is a suitable alternative for packaging materials; however, its biodegradation can also lead to instability in its usage. Cyclic polyphenylene sulfide (7U) has been shown to form rotaxane structures with PCL by simple blending to generate the π-π stacking effect and movable cross-link. A 2-fold increase in toughness and no decrease in Young's modulus for the PCL-based polyurethane with 7U are observed. The rotaxane structures mainly exist in the amorphous regions and have no impact on the crystallinity of PCL. Under the catalysis of lipase in aqueous solution, the stability of PCL is improved due to the 7U's suppression of the attack from the enzymes on PCL. After dissolution of the PCL films in the organic solvent, the dispersion of 7U and the breakage of the cross-links lead to little suppression on degradation during the catalysis of lipase. Thus, the controlled stability of PCL using 7U can prolong the life span of the biodegraded PCL materials.

Photovoltaic effects in BiVO4/ZnTiO3 multilayer films with high fill factor

Bismuth-based semiconductor materials have garnered significant attention because of their appropriate optical bandgap and substantial photoelectric conversion efficiency. Enhancing the photocurrent and fill factor of photovoltaic films is essential for developing high-performance optoelectronic devices. In this study, high-performance BiVO4-ZnTiO3 multilayer films were fabricated using a straightforward sol-gel method, where the incorporation of ZnTiO3 films significantly improved the photovoltaic performance of BiVO4. Through structural design aimed at enhancing light utilization, the BiVO4-ZnTiO3 multilayer film achieved a photocurrent density of 1.9 mA/cm2 at 450 nm, along with a fill factor of 46.8 % in the composite multilayer structure. The improvement in film performance is attributed to the overall multilayer stacking effect. This study offers a novel approach for utilizing bismuth-based semiconductors in optoelectronics.

Precise Regulation of Interlayer Stacking Modes in Trinuclear Copper Organic Frameworks for Efficient Photocatalytic Reduction of Uranium(VI).

The interlayer stacking modes of 2D covalent-organic frameworks (COFs) directly influence their structural features, ultimately determining their functional output. However, controllably modulating the interlayer stacking structure in traditional 2D metal-free COFs, based on the same building blocks, remains challenging. Here, two trinuclear copper organic frameworks are synthesized successfully with different interlayer stacking structures: eclipsed AA stacking in Cu3-PA-COF-AA and staggered ABC stacking in Cu3-PA-COF-ABC, using the same monomers. Remarkably, various functionalities, including porosity and electronic and optical properties, can be effectively regulated by interlayer stacking. As a result, Cu3-PA-COF-AA and Cu3-PA-COF-ABC exhibit significantly different activities toward the photoreduction of U(VI), presenting a promising strategy for removing radioactive uranium pollution. Due to its broader visible-light absorption range and superior photogenerated carrier migration and separation efficiency, Cu3-PA-COF-AA achieves a U(VI) removal ratio of 93.6% without additional sacrificial agents in an air atmosphere-≈2.2 times higher than that of Cu3-PA-COF-ABC (42.0%). To the best of the knowledge, this is the first study to elucidate the effect of interlayer stacking in COFs on the photocatalytic activity of U(VI) reduction. This finding may inspire further exploration of the structure-function relationship in COFs as photocatalysts and their potential for photoinduced removal of radionuclides.

Investigation of the effect of symmetrical hybrid stacking on drilling machinability of unidirectional CFRP, GFRP and hybrid composites: Drilling tests and damage analysis

Fiber-reinforced plastics are undoubtedly superior to metals in many sectors due to their advantageous properties. Especially carbon fiber reinforced plastics (CFRP) and glass fiber reinforced plastics (GFRP) are widely used in industry. Although CFRP offers higher strength, its use is limited due to its high cost. However, with hybridisation, it is possible to produce composites that will provide sufficient strength at lower cost. The mechanical behaviour of hybrid composites may be different compared to glass or carbon composites, as well as the damage behaviour during machining. In this study, the influence of hybrid stacking in drilling hybrid composites was investigated. The results showed the hybrid stacking, especially the position of the carbon plate, has a significant impact on the force generation and damage formation in the drilling. Although stacking the carbon layer at bottom caused an increase in thrust forces, it reduced the damage formation at the hole exit.

Alginate/organo-selenium composite hydrogel beads: Dye adsorption and bacterial deactivation

Post-COVID-19, the risk and spread of germs, coupled with wastewater contamination, have become critical concerns. Wastewater contains waterborne bacteria and various contaminants like dye molecules, threatening water safety. Traditional adsorption methods address pollutant removal or pathogen inactivation separately, but a dual-action solution is increasingly essential. This study presents alginate/selenium composite hydrogel beads with the potential to simultaneously remove dyes and deactivating bacteria. Fabricated by dropping suspension droplets into a calcium ion bath, these beads were tested for dye adsorption and antibacterial efficacy. Beads with 50 wt% organo‑selenium demonstrated the highest methylene blue (MB) adsorption capacity and nearly 100 % deactivation efficiency against Pseudomonas aeruginosa, while those with 20 wt% showed no significant improvement. Mechanistic studies reveal that organo‑selenium induces stacking effects and reduces surface charges, enhancing MB adsorption and antibacterial performance. The alginate/organo‑selenium composite hydrogel beads offer a potential effective and sustainable solution for tackling the complex issue of wastewater pollutants.

Construction of MXene interlayer conductive ion transport channel by polypyrrole-coated cellulose nanofibers for ultralow voltage high-performance ionic soft actuators

Ionic soft actuators are extensively utilized in soft robotics and intelligent flexible devices due to their low-voltage actuation capability. MXene(Ti3C2Tx) has potential value as an electrode material for ionic soft actuators owing to its high conductivity and large specific surface area. However, the actuation performance of its ionic soft actuator is limited by poor extensibility and low capacitance caused by the stacking effect. Here, a high-performance ionic soft actuator with MXene\\polypyrrole-coated cellulose nanofibers (CNF@PPy) is reported. While gaining high flexibility of the electrode due to the great mechanical property of CNF, the fast conductive transport channel is constructed by doping CNF@PPy between MXene layers, which not only effectively reduces the loss of conductive properties and drastically improves the ion migration rate, but also prevents MXene from stacking and has additional chemical active sites, significantly increasing its ion storage capacity. Consequently, the actuator exhibits excellent actuation performance at the 0.5 V ultralow voltage: 0.79 % bending strain, 6 s rapid response, and 91.03 % high durability after 5 hours. Additionally, the potential for the actuating core of advanced flexible electronic devices is demonstrated by the application of flexible forceps and the flexible electronic eye.

Multiple enhancement effects of dipoles within polyimide cathode promoting highly efficient energy storage of lithium-ion batteries

Polyimide (PI) has been recognized as a potential organic cathode for Li-ion batteries (LIBs) due to its programmable structural design, high theoretical capacity, and resource availability. However, the poor intrinsic electrical conductivity of PI means that PI-based cathodes of LIBs have inefficient energy storage performance, especially at high current densities. In this work, the molecular structure of PI is optimized to obtain a layer-stacked crystalline PI with significantly enhanced dipoles, denoted NT-B for the first time. The dipoles in this PI are induced by the electronegative carbonyl groups from the monomer biuret and further enhanced via a π-π layer stacking effect. This work is the first to verify that the co-directional dipole enhancement effect of biuret is surprisingly different from that of monomer urea. A series of ex-situ/in-situ and theoretical DFT simulations are carried out to understand the functional mechanism of such effects. The multiple enhancement effects of the dipoles synergistically promoting the generation of a strong built-in electric field (BIEF) within NT-B are proposed based on the results obtained. It is confirmed that this BIEF plays a significant role in accelerating electron transport, which enhances the electrochemical activity of LIB cathodes. This work provides a new idea for the structural design of high-performance PI cathodes for LIBs.

Redox Activity Modulation in Extended Fluorenone-Based Flow Battery Electrolytes with π-π Stacking Effect

Redox flow battery shows promise for grid-scale energy storage. Aqueous organic redox flow batteries are particularly popular due to their potentially low material cost and safe water-based electrolyte. Commonly, redox active molecules used in this field feature aromatic rings, and increasing π-aromatic conjugation has been a popular strategy to achieve high energy density, high power density, and reduced crossover in new material design. However, this approach can inadvertently hinder redox activity depending on redox mechanism. This study reveals the underlying π-π stacking effect in extended aromatic redox active compounds, where aromatic radical intermediates are involved in the redox process. We report a molecular design strategy to mitigate the negative effect of π-π stacking by altering solvation dynamics and introducing molecular steric hindrance.

Kinetically Controlled Preparation of Worm-like Micelles with Tunable Diameter/Length and Structural Stability.

Anisotropic nanoparticles such as worm-like micelles have aroused much attention due to their promising applications from templates to drug delivery. The fabrication of worm-like micelles with tunable structural stability and control over their diameter and length is of great importance but still challenging. Herein, we report a kinetically controlled ring-opening metathesis polymerization-induced self-assembly (ROMPISA) for the robust preparation of kinetically trapped worm-like micelles with tunable diameter/length at enlarged experimental windows by the rational manipulation of kinetic factors, including solvent property, temperature, and π-π stacking effects. The resultant worm structures were thermodynamically metastable and capable of excellent structural stability at room temperature due to the kinetic trapping effect. At elevated temperatures, these thermodynamically metastable worms could undergo morphology evolution into vesicular structures in a controlled manner. Moreover, the structural stability of worms could also be significantly enhanced by in situ cross-linking. Overall, this kinetically controlled ROMPISA opens a new avenue for PISA chemistry that is expected to prepare "smart" polymer materials by manipulating kinetic factors.

An electrochemical aptamer-sensing strategy based on a Ti3C2Tx MXene synergistic Ti-MOF amplification signal for highly sensitive detection of zearalenone

A refined electrochemical aptamer sensing technique using PEI@Ti-MOF@Ti3C2Tx-MXene was developed for the sensitive detection of ZEN in food samples. A titanium-based metal-organic skeleton (NH2-MIL-125) was synthesized in situ using 2-aminoterephthalic acid as the organic ligand and tetrabutyl titanate as the metal center, followed by the simultaneous hybridization of Ti3C2Tx-MXene to synthesize a Ti-MOF@Ti3C2Tx-MXene composite material. These composites were subsequently functionalized with PEI and covalently linked to form a sensing platform on gold electrodes. Integrating a metal-organic framework (MOF) with MXene materials not only improved the electrochemical properties compared to those of individual elements but also decreased the stacking effect and increased the number of binding sites for the aptamer. The limit of detection (LOD) of this sensor was 1.64 fg mL−1. Additionally, the sensor could efficaciously detect ZEN in cornmeal and beer samples, exhibiting outstanding stability, reproducibility, and selectivity. This highlighted its effectiveness in applications in quality supervision and food safety.

Two Different Chiral Groups Based Thermally Activated Delayed Fluorescence Materials for Circularly Polarized OLEDs.

Circularly polarized organic light-emitting diodes (CP-OLEDs) hold significant promise for applications in 3D displays due to the ability to generate circularly polarized luminescence (CPL) directly. In this study, two pairs of circularly polarized thermally activated delayed fluorescence (CP-TADF) enantiomers, named RR/SS-ONCN and RS/SR-ONCN, were synthesized by integrating two distinct chiral groups into the dicyanobenzene unit. The RR/SS-ONCN and RS/SR-ONCN enantiomers show CPL properties with dissymmetry photoluminescence factors (|gPL|) of 1.3×10-3 and 2.0×10-3 in doped films, respectively. Notably, RR/SS-ONCN exhibit higher |gPL| values than that of RS/SR-ONCN, especially in doped films, indicating that when the configurations of the two chiral groups are identical, the |gPL| value of the CP-TADF materials can be enhanced, demonstrating a certain stacking effect. Moreover, the corresponding CP-OLEDs demonstrate good performances, achieving maximum external quantum efficiencies of up to 21.9 % and notable CP electroluminescence with |gEL| factors of up to 1.0×10-3.