Spatial Confinement Effect Research Articles

FINDER: A Fluidically Confined CRISPR-Based DNA Reporter on Living Cell Membranes for Rapid and Sensitive Cancer Cell Identification.

The accurate, rapid, and sensitive identification of cancer cells in complex physiological environments is significant in biological studies, personalized medicine, and biomedical engineering. Inspired by the natural confined enzyme on fluidic cell membrane, afluidically confined CRISPR-based DNA reporter (FINDER) was developed on living cell membranes, which was successfully applied for rapid and sensitive cancer cell identification in clinical blood samples. Benefiting from the spatial confinement effect for improved local concentration, and membrane fluidity for higher collision efficiency, the activity of CRISPR-Cas12a was, for the first time, found to be significantly enhanced on living cell membranes. This new phenomenon was then combined with multiple aptamers-based DNA logic gate for cell recognition, thus a FINDER system with accurate, rapid and sensitive cancer cell identification was constructed. The FINDER can rapidly identified target cells in only 20 min, and achieved over 80% recognition efficiency with only 0.1% of target cells presented in clinical blood samples, indicating its potential application in biological studies, personalized medicine, and biomedical engineering.

Orderly Aggregated Catalytic Hairpin Assembly for Synchronous Ultrasensitive Detecting and High-Efficiency Co-Localization Imaging of Dual-miRNAs in Living Cells.

In this work, the orderly aggregated catalytic hairpin assembly (OA-CHA) was developed for synchronous ultrasensitive detection and high-efficiency colocalization imaging of dual-miRNAs by a carefully designed tetrahedral conjugated ladder DNA structure (TCLDS). Exactly, two diverse hairpin probes were fixed on tetrahedron conjugated DNA nanowires to form the TCLDS without fluorescence response, which triggered OA-CHA in the aid of output DNA 1 and output DNA 2 produced by targets miRNA-217 and miRNA-196a cycle to generate TCLDS with remarkable fluorescence response. Impressively, compared with the traditional CHA strategy, OA-CHA avoided the fluorescence group and quenching group from approaching again because of the spatial confinement effect to significantly enhance the fluorescence signal, resulting in the simultaneous ultrasensitive detection of dual-miRNAs with detection limits of 21 and 32 fM for miRNA-217 and miRNA-196a, respectively. Meanwhile, the TCLDS with lower diffusivity could achieve accurate localization imaging for reflecting the spatial distribution of dual-miRNAs in living cells. The strategy based on OA-CHA provided a flexible and programmable nucleic amplification method for the synchronous ultrasensitive detection and precise imaging of multiple biomarkers and had potential in disease diagnostics..

The cactus bulb-shaped metal-S-C/N nanoparticles supported by highly conductive channels for efficient electrocatalytic hydrogen evolution reaction

Accelerating electron transfer and exposing active sites are key factors that could improve electrocatalytic hydrogen evolution reaction (HER). In this study, Co3S4-Ni3S2-C/N, the cactus bulb-shaped nanoparticles based on metal-organic frameworks (MOFs), were successfully prepared. The catalyst requires only 101 and 227 mV overpotential to reach current densities of 20 and 100 mA cm−2, respectively, in 1 M KOH. The high catalytic activity is attributed to the confinement effect achieved by introducing 2-aminoterephthalic acid as a precursor, allowing the catalyst to have a small particle size and fully exposed metal active sites. Moreover, the catalyst has a highly conductive metal-S-C/N channel that effectively reduces the intrinsic charge transfer resistance of the catalytic electrode, improves its conductivity, and modulates the electron density at the metal active site. Furthermore, compared to other crystal planes, the exposed (111) crystal plane of Co3S4 provides the most octahedral coordination of high spin state Co3+, which is highly catalytically active. This makes it the dominant crystal plane for catalysis. Through spatial confinement effect to limit metal sulfide particle size and introducing an organic backbone to create highly conductive metal-S-C/N channels, our study provides a general approach to developing highly active catalytic materials.

Intramolecular Accelerated Assembly of Molecular Beacons: A DNA Nanoarchitecture-based Spatial Confinement Strategy toward Terminal Deoxynucleotidyl Transferase Biosensing.

Physiological function analysis of terminal deoxynucleotidyl transferase (TdT) in clinical medicine and hematopathology highlights its significance to be extensively utilized as a diagnostic biomarker for leukemia diagnosis. Herein, taking advantage of the spatial-confinement effect on a three-dimensional (3D) DNA nanoarchitecture, we reported a target-triggered intramolecular accelerated molecular beacon (MB) assembly for rapid and real-time analysis of TdT activity. In this strategy, the 3D DNA nanoarchitecture is first engineered via a cross-linking network hybridization chain reaction (HCR). A number of MBs, which were designed with a polythymine (poly-T) loop, were then conjugated on the scaffold DNA nanoarchitecture, allowing the obtained MB-DNA nanoarchitecture to contain lots of free 3'-hydroxyl (OH) termini inside or outside the super DNA nanostructure. Moreover, the distance between different MBs is closed, and the local concentration of MB is significantly improved owing to the confinement of MBs on this DNA nanoarchitecture. Once encountered with target TdT, the free -OH groups can be recognized by TdT immediately to catalyze the template-independent incorporation of adenine nucleotides, which results in the generation of multiple poly-A chains that rapidly react with many MBs via an intramolecular accelerated assembly process. The time-dependent substantial enhancement of the fluorescence from MBs can thus be applied for robustly analyzing TdT. Our observations suggest that the DNA nanostructure-based spatial confinement effect enables a high molecular collision frequency to accelerate the reaction kinetics, and the super DNA nanoarchitecture exhibits a better nuclease resistance to maintain signal stability. With these advantages, TdT can be rapidly detected with high sensitivity, specificity, and biostability.

Double-Confinement Construction of Atomically-Dispersed-Fe Bifunctional Oxygen Electrocatalyst for High-Performance Zinc-Air Battery.

Simultaneously achieving high activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is the key to constructing rechargeable Zn-air batteries (ZABs). Here the complexation of 1,10-phenanthroline and the spatial confinement effect of closo-[B12 H12 ]2- are used to solidify metal-boron-cluster-organic-polymers on the surface of SiO2 microspheres to construct a bifunctional oxygen electrocatalyst (FeBCN/NHCS). Driven by FeBCN/NHCS, the half-wave-potential of ORR surpasses that of the Pt/C catalyst, reaching 0.893V versus RHE, and the overpotential (η10 ) of OER is as low as 361mV. The ZABs of FeBCN/NHCS as an air cathode not only have high power density and specific capacity, but also have charge-discharge durability. The FeBCN/NHCS is not only related to the high specific surface area, but also the high exposure rate of single-atom Fe and the doping of heteroatom B. This study provides an efficient oxygen electrocatalyst and also contributes wisdom to the acquisition of highly active oxygen electrocatalyst.

Synthesis, Types, and Applications of Zeolite Capsule Catalysts

AbstractCapsule catalysts offer a unique spatial confinement effect, which effectively minimizes byproduct formation, enhances catalyst life, and promotes tandem reactions, thus reducing energy, time, and raw material consumption. This review presents an overview of recent advances and research progress in capsule catalysts, highlighting major breakthroughs in preparation strategies over the past decade. Innovative synthesis methods are discussed based on synthesis principles, difficulty, and effectiveness, along with an analysis of growth mechanisms and the advantages and disadvantages of zeolite shells. Application status of capsule catalysts in high‐value hydrocarbon synthesis from syngas, low‐carbon alkane dehydroaromatization, and CO2 hydrogenation reactions is explored. Finally, challenges and future prospects for scientific research and industrial applications of capsule catalysts are addressed.

Lattice Distortion in a Confined Structured ZnS/ZnO Heterojunction for Efficient Photocatalytic CO2 Reduction.

It is a promising strategy to effectively promote "carbon neutrality" by reducing CO2 to small energy molecules through photocatalysis technology. However, due to low light utilization and recombination of photogenerated carriers, photocatalysts usually have low activity and low selectivity for products. Herein, a hollow spherical ZnS/ZnO heterojunction with a spatial confinement effect photocatalyst was synthesized toward CO2 photoreduction through preciously controlling the nano-/microstructure. The local lattice distortions were introduced into the surface of the hollow ZnS/ZnO microsphere, which activated lattice oxygen and provided additional active reaction sites. Furthermore, the heterojunction constructed between ZnS and ZnO interfaces facilitated the separation of photoinduced charge carriers. Combined with the natural advantage of enhanced light capture and absorption for a hollow confined structure, as a result, the systemic design in the electronic and confined structures for the photocatalyst has brought an excellent CO2 reduction performance with a CO yield rate as high as 35.85 μmol g-1h-1 and durability under a 300 W Xe lamp irradiation without any sacrificial agent and cocatalyst.

Coral-like, self-assembled, and spatially bounded Ag nano-particles on franzinite zeolite composite sensor toward accurate, synergetic, and ultra-trace sulfadiazine detection

A coral-like Ag@FRA zeolite nanocomposite sensor reveals high sensitivity toward sulfadiazine (SDZ) in a dual detection of fluorescence and electrochemistry. The sensor has been as-synthesized in the hydrothermal condition through a one-pot self-assembly process in which the high crystalline Ag nanoparticles (NPs) are closely arranged and stacked on the nanosized surface cage window of the FRA (Franzinite) zeolite. Strong ultrasound can drive the coral-like composite release Ag nanoparticles whose distribution range mainly from 10 to 12 nm lead to the purple fluorescence in an emission spectrum. In sea water, the fluorescence increases linearly in the SDZ concentration range of 5 × 10−18-5 × 10−10 M. Furthermore, the LOD (limit of detection) reaches 1.4 × 10−22 M by the spatial confinement effect of the coral-liked FRA cage structure in CV (cyclic voltammetry) method at the characteristic potential peak position of 0.1 V vs. SCE. The theoretical calculation also confirms that the FRA cage structure matches well with the SDZ molecules. Further studies indicate the generation of a novel stable composite sensor with high specificity, good recovery and repeatability, which depends on the induction of silver ions upon the artificial synthesis of FRA.

Effects of vibration conditions, spatial confinement and friction on mixing and segregation characteristics of mixed pebble beds for CFETR WCCB blanket

This paper presents the study of the dynamic characteristics of confined mixed pebble beds with different friction under different vibration conditions using the discrete element method. The λ segregation index is used to quantify the degree of particle mixing or segregation. The percolation, convection and diffusion mechanisms are responsible for the segregation patterns of the mixed pebble. The results show the degree of segregation can be suppressed by decreasing the vibration acceleration or free space height below a threshold. Further simulation reveals the threshold of vibration acceleration or free space height both are related to the bed height increment which determines the strength of the percolation mechanism. In addition, the strength of percolation and convection becomes weaker by decreasing the friction of particles and walls, which makes the pebbled bed remains in a mixed state under vibration. These findings are significant to clarify the main factors behind the three segregation mechanisms and hence provide solutions to retaining the mixed state of the Li2TiO3&Be12Ti mixed pebble bed.

Simultaneous Response of Mitochondrial MicroRNAs to Identify Cell Apoptosis with Multiple Responsive Intelligent DNA Biocomputing Nanodevices.

Challenges remained in precisely real-time monitoring of apoptotic molecular events at the subcellular level. Herein, we developed a new type of intelligent DNA biocomputing nanodevices (iDBNs) that responded to mitochondrial microRNA-21 (miR-21) and microRNA-10b (miR-10b) simultaneously which were produced during cell apoptosis. By hybridizing two hairpins (H1 and H2) onto DNA nanospheres (DNSs) that had been previously modified with mitochondria-targeted triphenylphosphine (TPP) motifs, iDBNs were assembled in which two localized catalytic hairpins self-assembly (CHA) reactions occurred upon the co-stimulation of mitochondrial miR-21 and miR-10b to perform AND logic operations, outputting fluorescence resonance energy transfer (FRET) signals for sensitive intracellular imaging during cell apoptosis. Owing to the spatial confinement effects of DNSs, it was discovered that iDBNs had a high efficiency and speed of logic operations by high local concentrations of H1 and H2, making the simultaneous real-time responses of mitochondrial miR-21 and miR-10b reliable and sensitive during cell apoptosis. These results demonstrated that iDBNs were simultaneously responsive to multiple biomarkers, which greatly improved the detection accuracy to identify the cell apoptosis, demonstrating that iDBNs are highly effective and reliable for the diagnosis of major disease and screening of anticancer drugs.

Atomic Engineering Modulates Oxygen Reduction of Hollow Carbon Matrix Confined Single Metal-Nitrogen Sites for Zinc-Air Batteries.

The systematical understanding of metal-dependent activity in electrocatalyzing oxygen reduction reaction (ORR), a vital reaction with sluggish kinetics for zinc-air batteries, remains quite unclear. An atomic and spatial engineering modulating ORR activity over hollow carbon quasi-sphere (HCS) confined in a series of single M-N (M = Cu, Mn, Ni) sites is reported here. Based on the theoretical prediction and experimental validation, Cu-N4 site with the lowest overpotential shows a better ORR kinetics than Mn-N4 and Ni-N4 . The ORR activity of single-atom Cu center can be further improved by decreasing the coordination number of N to two, namely Cu-N2 , due to the enhancement of electrons with lower coordination structure. Benefitting from the unique spatial confinement effect of the HCS structure in modulating electronic feature of active sites, the Cu-N2 site confined in HCS also delivers highly improved ORR kinetics and activity relative to that on planner graphene. Additionally, the best catalyst holds excellent promise in the application of zinc-air batteries. The findings will pave a new way to atomically and electronically tune active sites with high efficiency for other single-atom catalysts.

Characteristic and function of the dynamic Al-AlN core-shell structure in Al-Al2O3 composite at elevated temperature

An Al-AlN core-shell structure with spatial confinement effect is set up in Al-Al2O3 composite by pre-nitriding at 580 °C in flowing nitrogen. Its detailed characteristic and function evolution was examined over the temperature range from 600 °C to 1500 °C. With the temperature increase, the as formed Al-AlN core-shell structure in the composite undergoes two typical stages. First, from 660 °C to 900 °C, AlN shell is intact and serves as an “eggshell” to localize the molten Al core inside. When the temperature rises above 900 °C, AlN shell begins to crack under thermal stress, and the micronized Al cluster (mixture of droplets and vapor) was extracted out gradually. In this period, AlN shell serves as a slowly-released structure to control the gradual exposure of Al core and their conversion to highly-reactive micronized Al(l) and Al(g). On this basis, the controllable synthesis of AlN-based reinforcements can be realized by adjusting the nitriding path of Al with different states and scales. The detailed analysis of the dynamic Al-AlN core-shell structure at elevated temperature contributes to the better phase and morphology control of the Al-Al2O3 composite for metallurgy.

Encapsulation of Tetraphenylethylene Derivative in Liposome Vesicles as Promising Aggregation-Induced Electrochemiluminescence Emitter for Detection of Human Epidermal Growth Factor Receptor 2.

In this work, a sensitive signal-on electrochemiluminescence biosensor using liposome-encapsuled 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE) as a promising aggregation-induced electrochemiluminescence (AIECL) emitter for detection of biomarkers was developed. Aggregation-induced enhancement occurs internally through the spatial confinement effect and intramolecular self-encapsulation of encapsulating TPE and triethylamine (TEA) molecules in liposome cavities. Peptide sequence WTGWCLNPEESTWGFCTGSF (WF-20) was used to replace the antibody for reducing the steric hindrance of the sensing surface while taking into account the affinity. The proposed sensing strategies showed satisfactory properties for detection of human epidermal growth factor receptor 2 (HER2) ranging from 0.01 to 500 ng/mL with a limit of detection of 6.65 pg/mL. The results confirmed that encapsulation of luminescent molecules in the vesicle structure for triggering the AIECL phenomenon is a promising method to prepare a signal label for a trace detection biomarker.

Heterostructured Interface Enables Uniform Zinc Deposition for High-Performance Zinc-Ion Batteries.

Zinc metal has considerable potential as a high-energy anode material for aqueous batteries due to its high theoretical capacity and environmental friendliness. However, dendrite growth and parasitic reactions at the electrode/electrolyte interface remain two serious problems for the Zn metal anode. Here, the heterostructured interface of ZnO rod array and CuZn5 layer is fabricated on the Zn substrate (ZnCu@Zn) to address these two issues. The zincophilic CuZn5 layer with abundant nucleation sites ensures the initial uniform Zn nucleation process during cycling. Meanwhile, the ZnO rod array grown on the surface of the CuZn5 layer can guide the subsequent homogeneous Zn deposition via spatial confinement and electrostatic attraction effects, leading to the dendrite-free Zn electrodeposition process. Consequently, the derived ZnCu@Zn anode exhibits an ultra-long lifespan of up to 2500h with symmetric cells at the current density and capacity of 0.5mAcm-2 /0.5mAhcm-2 . Besides, a remarkable cyclability (75% retention for 2500 cycles at 2Ag-1 ) is achieved in the ZnCu@Zn||MnO2 full cell with a capacity of 139.7mAhg-1 . This heterostructured interface with specific functional layers provides a feasible strategy for the design of high-performance metal anodes.

Preliminary study of laser-induced breakdown spectroscopy for non-destructive pressure measurement in confined vacuum interlayers

The pressure measurement within a closed vacuum chamber is a crucial indicator for evaluating vacuum performance. The commonly used puncture and sampling method is destructive to the device. This paper presents a new method based on laser-induced breakdown spectroscopy (LIBS) to evaluate the pressure inside a confined, transparent vacuum sandwich. The intensity of the emission spectra of copper sheets inside the sandwich was tested at different pressures, and three cylindrical cavities of different heights were subjected to experiments. The results show that the Cu and O intensity ratio varies linearly with gas pressure in the 1–103 Pa range, which can be used to predict the pressure inside the interlayer. It is fast, non-destructive, and remotely detectable. This work extends the application of LIBS for spatial confinement effects to enhance the spectral intensity and provides a new idea for pressure measurement in confined devices.

Line-shape analysis and simulation of Er3+ photoluminescence spectra in erbium-stabilized nanocrystalline zirconia structures

Peculiarities of the near-infrared and visible up-conversion spectra of nanocrystalline (Er2O3)x (ZrO2)1-x have been studied. It is shown that for the samples with 0.026 < x < 0.143 the photoluminescence spectra of Er3+ are defined a by similar erbium environment in spite of the different symmetry of the host ZrO2 matrix. The low temperature and room temperature emission bands in the spectral range of the 4I13/2 → 4I15/2 transition are measured and interpreted in terms of the multi-electron molecular orbitals cluster model developed for the case of nanocrystal structures. The role of the intra-manifold 4I13/2 relaxation caused by the spatial confinement effects in erbium-stabilized nanocrystalline zirconia is discussed.

Mechanistic insights into dual function of graphene oxide in preparing Starch-derived amorphous carbon for lithium storage

Graphene oxide is demonstrated as an effective promoter for the direct conversion of starch into high-value carbon materials during carbonization process. However, the detailed mechanisms of graphene oxide in avoiding starch foaming and driving the growth of carbonaceous solid remain unclear. Herein, using thermal analysis and gas–liquid-solid products analysis, we identify the dual function of graphene oxide in the transformation of starch into porous carbon spheres. At the physical level, through a spatial confinement effect, graphene oxide coating not only separates starches from each other, but also blocks the bio-tar produced by starch foaming, inducing the secondary decomposition of tars and the formation of carbon skeleton, resulting in a high carbon yield. At the chemical level, graphene oxide coating induces the quantitative dehydration of starch, which means a controllable foaming degree and provides an adjustable pore structure of the as-obtained carbon. When serving as an anode material for lithium storage, it exhibits a high capacity of 665 mAh g−1 at 20 mA g−1 and a good cycle stable. These results provide a deeper understanding for the controllable conversion of starch into carbon driven by graphene oxide, which can potentially promote the practical application of biomass-derived carbon materials in energy storages.

Reconstruction of helmholtz plane to stabilize zinc metal anode/electrolyte interface

Dendrites proliferation and parasitic side reactions on zinc metal anodes (ZMAs) severely weaken the energy efficiencies of aqueous zinc metal batteries (AZMBs). Herein, an effective Helmholtz plane (HP) reconstruction mechanism on ZMAs in ZnSO4 electrolyte activated by zinc pyrrolidone carboxylate (PCA-Zn) additive is proposed. Systematical experiments together with numerical simulations identified that the dissociated PCA− anions featuring bis-zincophilic-terminal preferentially adhere to the ZMAs surface with carboxyls serving as anchors to replace H2O and SO42−, reshaping an H2O/SO42−-repellent HP to restrain water-triggered side reactions. Meanwhile, the other free zincophilic carbonyl terminals of PCA− anions endow the restructured HP with spatial confinement effect on Zn2+, effectively suppressing their rampant in-plane diffusion and homogenizing ions flux during Zn deposition. Moreover, the HP exhibits a self-repair behavior against unexpected electrode surface damage upon cycling. Benefiting from the multifunctional HP that enables more stable ZMAs/electrolyte interphasial chemistry, an excellent Zn||Zn symmetric electroplating/stripping cyclic durability exceeding 300 h under a depth of discharge up to 40% (20 mA cm−2/20 mAh cm−2) is achieved, accounting for significantly boosted rechargeability (89.7% capacity holding ratio after 5000 cycles) of the carbon-cloth@polyaniline||ZMA full AZMBs compared to that without PCA-Zn additive (malfunction after only 960 cycles).

Aggregation-Induced Electrochemiluminescence Frame of Silica-Confined Tetraphenylethylene Derivative Matrixes for CD44 Detection via Peptide Recognition.

The theory of aggregation-induced electrochemiluminescence (AIECL) has introduced new vitality into preparing new electrochemiluminescence (ECL) emitters. However, the progress in the application of biosensing analysis has been slow owing to the lack of AIECL-based functional nanomaterials. Herein, a biosensor was fabricated using mesoporous silica nanosphere (MSN) matrix-confined 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE) as a well-ordered ECL emitter and self-designed WHPWSYC (WC-7) heptapeptide as the target capturer for CD44 detection. TPE and its co-reactant, triethylamine (TEA), were encapsulated in the MSN nanomatrix to enhance the radiation transition by limiting the intramolecular rotation of TPE molecule benefit from the spatial confinement effect, and the ECL intensity is self-enhanced by replacing electron free diffusion in the conventional ECL system. MSN-TPE-TEA can act as satisfactory sensing substrates that improve the reproducibility and batch-to-batch consistency of biosensors and functions as a stable signal label for trace analysis of biomarkers. As a substitute for antibody and hyaluronic acid, the WC-7 heptapeptide significantly reduced the steric hindrance of the sensing interface in CD44 affinity tests. Combined with the DNA strand displacement reaction, this strategy shows a good ECL response to standard CD44 antigen and MCF-7 cells with different concentrations, which is another feasible method for detecting CD44 in body fluids or living cells.

Amine-impregnated porous carbon–silica sheets derived from vermiculite with superior adsorption capability and cyclic stability for CO2 capture

Amine-functionalized adsorbents have become one of the most promising capture technologies for greenhouse gas mitigation. However, developing cost-effective adsorbents with high adsorption capacity and superior cyclic stability via temperature swing adsorption remains difficult. Herein, sandwich-like polyethyleneimine (PEI)-impregnated porous carbon–silica sheets derived from vermiculite (AEVCP) adsorbents were successfully synthesized via porous carbon network confined within acid activated expanded vermiculite derived silica (AEV) sheets and interlayer amine-functionalization with PEI impregnation. The effect of adsorption temperature on CO2 adsorption performances, adsorption/desorption kinetics and thermodynamics for AEVCP adsorbents were specifically discussed. The optimal AEVCP50 adsorbent possessed a large CO2 uptake of 1.84 mmol/g at 75 ℃ in 60 vol% CO2/40 vol% N2 and superior cyclic stability with 7.6 % decay after 10 cycles, due to the hierarchical porous structure and high thermal conductivity of porous carbon–silica sheets derived from vermiculite (AEVC) support. The unique sandwich-like features of AEVC support are favorable for the high amine loading, rapid CO2 diffusion and efficient capture. The interlayer carbon implantation and amine-functionalization with strong interlayer spatial confinement effect, can suppress the formation of urea linkages, avoid the persistent over-heating and excess amine agglomeration, and enhance the gas diffusion and thermal transfer during the adsorption isobar process, which ultimately lead to superior adsorption capability and cyclic stability for CO2 capture. This design approach of cost-effective adsorbents derived from natural minerals provides a new avenue for practical CO2 capture and separation processes.