Beta-Cyclodextrin-Modified Covalent Organic Framework Nanochannel for Electrochemical Chiral Recognition of Amino Acids.

The chiral recognition and separation of enantiomers are of great importance for biological research and the pharmaceutical industry. Preparing homochiral materials with adjustable size and chiral binding sites is beneficial for achieving an efficient chiral recognition performance. Here, a homochiral covalent organic framework membrane modified with ß-cyclodextrin (CD-COF) was constructed, which was subsequently utilized as an electrochemical sensor for the enantioselective sensing of tryptophan (Trp) molecules. The preferential adsorption of l-Trp over d-Trp at the ß-CD sites can enhance the surface charge density and hydrophilicity of the CD-COF membrane, resulting in an increased transmembrane ionic current. Trp enantiomers with concentrations down to 0.28 nM can be effectively discriminated. The l-/d-Trp recognition selectivity increases with the Trp concentration and reaches a value of 19.2 at 1 mM. The selective adsorption of l-Trp to the CD-COF membrane will also hinder its transport, resulting in a l-/d-Trp permeation selectivity of 15.3. This study offers a new strategy to construct homochiral porous membranes and achieve efficient chiral sensing and separation.

Endowing Metal-Organic Coordination Materials with Chiroptical Activity by a Chiral Anion Strategy.

Recently, chiral metal-organic coordination materials have emerged as promising candidates for a wide range of applications in chiroptoelectronics, chiral catalysis, and information encryption, etc. Notably, the chiroptical effect of coordination chromophores makes them appealing for applications such as photodetectors, OLEDs, 3D displays, and bioimaging. The direct synthesis of chiral coordination materials using chiral organic ligands or complexes with metal-centered chirality is very often tedious and costly. In the case of ionic coordination materials, the combination of chiral anions with cationic, achiral coordination compounds through noncovalent interactions may endow molecular materials with desirable chiroptical properties. The use of such a simple chiral strategy has been proven effective in inducing promising circular dichroism and/or circularly polarized luminescence signals. This concept article mainly delves into the latest advances in exploring the efficacy of such a chiral anion strategy for transforming achiral coordination materials into chromophores with superb photo- or electro-chiroptical properties. In particular, ionic small-molecular metal complexes, metal clusters, coordination supramolecular assemblies, and metal-organic frameworks containing chiral anions are discussed. A perspective on the future opportunities on the preparation of chiroptical materials with the chiral anion strategy is also presented.

Ratiometric Imaging Detection of Amyloid-ß Fibrils by a Dual-Emissive Tris-Heteroleptic Ruthenium Complex.

Two dual fluorescent/phosphorescent tris-heteroleptic mononuclear Ru(ΙΙ) complexes (2 and 3) were designed and applied in amyloid-ß (Aß) sensing. These complexes have a general formula of [Ru(phen)(dppz)(L)](PF6)2, where L is (2-pyrazinyl)(2-pyridyl)(methyl)amine (H-L) with different substituents (-OMe for 2, -H for 3), phen is 1,10-phenanthroline, and dppz is dipyridophenazine, respectively. Compared with the previously reported ratiometric probe 1 with a di(pyrid-2-yl)(methyl)amine ligand, complex 2 can be employed for not only ratiometric emissive detection of Aß aggregation but also ratiometric imaging detection of Aß fibrils. In ratiometric emissive detection, as the incubation time of the Aß sample (Aß40 and Aß42) was prolonged, a new phosphorescence emission band appeared with gradual enhancement of the emission intensity, while the fluorescence emission was basically unchanged, which could be treated as an intrinsic internal reference signal. In comparison, a larger ratiometric photoluminescence enhancement (I640/I440) was observed for Aß40 aggregation with respect to Aß42. In ratiometric imaging detection, the imaging signals obtained from the phosphorescence emission are much brighter than the fluorescence emission in both Aß40 and Aß42 fibrils. As indicated by molecular docking results, stronger interactions were found between complex 2 with Aß40 fibrils, which included π/π, π/C-H, and π/H interactions between bidentate ligands dppz and phen with amino acid residues. Moreover, computational calculations were carried out to assist the interpretation of these experimental findings.

Boost the Circularly Polarized Phosphorescence of Chiral Organometallic Platinum Complexes by Hierarchical Assembly into Fibrillar Networks.

Circularly polarized luminescence (CPL)-active molecular materials have drawn increasing attention due to their promising applications for next-generation display and optoelectronic technologies. Currently, it is challenging to obtain CPL materials with both large luminescence dissymmetry factor (glum) and high quantum yield (Φ). A pair of enantiomeric N N C-type Pt(II) complexes (L/D)-1 modified with chiral Leucine methyl ester are presented herein. Though the solutions of these complexes are CPL-inactive, the spin-coated thin films of (L/D)-1 exhibit giantly-amplified circularly polarized phosphorescences with |glum| of 0.53 at 560 nm and Φair of ~50 %, as well as appealing circular dichroism (CD) signals with the maximum absorption dissymmetry factor |gabs| of 0.37-0.43 at 480 nm. This superior CPL performance benefits from the hierarchical formation of crystalline fibrillar networks upon spin coating. Comparative studies of another pair of chiral Pt(II) complexes (L/D)-2 with a symmetric N C N coordination mode suggest that the asymmetric N N C coordination of (L/D)-1 are favorable for the efficient exciton delocalization to amplify the CPL performance. Optical applications of the thin films of (L/D)-1 in CPL-contrast imaging and inducing CP light generation from achiral emitters and common light-emitting diode lamps have been successfully realized.

Vaporchromic Domino Transformation and Polarized Photonic Heterojunctions of Organoplatinum Microrods.

Photonic heterostructures with codable properties have shown great values as versatile information carriers at the micro- and nanoscale. These heterostructures are typically prepared by a step-by-step growth or post-functionalization method to achieve varied emission colors with different building blocks. In order to realize high-throughput and multivariate information loading, we report here a strategy to integrate polarization signals into photonic heterojunctions. A U-shaped di-Pt(II) complex has been assembled into highly polarized yellow-phosphorescent crystalline microrods (Y-rod) by strong intermolecular Pt⋅⋅⋅Pt interaction. Upon end-initiated desorption of the incorporated CH2Cl2 solvents, the Y-rod is transformed in a domino fashion into tri-block polarized photonic heterojunctions (PPHs) with alternate red-yellow-red emissions or red-phosphorescent microrods (R-rods). The red emissions of these structures are also highly polarized; however, their polarization directions are just orthogonal to those of the yellow phosphorescence of the Y-rod. With the aid of a patterned mask, the R-rod can be further programmed into multi-block PPHs with precisely controlled block sizes by side-allowed adsorption of CH2Cl2 vapor. X-ray diffraction analysis and theoretical calculations suggest that the solvent-regulated modulation of the crystal packing and excited-state property is critical for the construction of these PPHs.

Divergent Synthesis of Enantioenriched Silicon-Stereogenic Benzyl-, Vinyl- and Borylsilanes via Asymmetric Aryl to Alkyl 1,5-Palladium Migration.

Functionalization of Si-bound methyl group provides an efficient access to diverse organosilanes. However, the asymmetric construction of silicon-stereogenic architectures by functionalization of Si-bound methyl group has not yet been described despite recent significant progress in producing chiral silicon. Herein, we disclosed the enantioselective silylmethyl functionalization involving the aryl to alkyl 1,5-palladium migration to access diverse naphthalenes possessing an enantioenriched stereogenic silicon center, which are inaccessible before. It is worthy to note that the realization of asymmetric induction at the step of metal migration itself remains challenging. Our study constitutes the first enantioselective aryl to alkyl 1,5-palladium migration reaction. The key to the success is the discovery and fine-tuning of the different substituents of α,α,α,α-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL)-based phosphoramidites, which ensure the enantioselectivity and desired reactivity.

Homochiral Zeolitic Imidazolate Framework with Defined Chiral Microenvironment for Electrochemical Enantioselective Recognition.

The recognition and separation of chiral molecules with similar structure are of great industrial and biological importance. Development of highly efficient chiral recognition systems is crucial for the precise application of these chiral molecules. Herein, a homochiral zeolitic imidazolate frameworks (c-ZIF) functionalized nanochannel device that exhibits an ideal platform for electrochemical enantioselective recognition is reported. Its distinct chiral binding cavity enables more sensitive discrimination of tryptophan (Trp) enantiomer pairs than other smaller chiral amino acids owing to its size matching to the target molecule. It is found that introducing neighboring aldehyde groups into the chiral cavity will result in an inferior chiral Trp recognition due to the decreased adsorption-energy difference of D- and L-Trp on the chiral sites. This study may provide an alternative strategy for designing efficient chiral recognition devices by utilizing the homochiral reticular materials and tailoring their chiral environments.

Closed Bipolar Electrode Array for Optical Reporting Reaction-Coupled Electrochemical Sensing and Imaging.

This review centers on a closed bipolar electrode (BPE) array using an electro-fluorochromism (EFC) or electro-chemiluminescence (ECL) reaction as the reporting reaction. Electrochemical signals at one pole of the closed BPE array can be transduced into the EFC or ECL signals at the opposite pole. Therefore, the current signal of a redox reaction can be easily detected and imaged by monitoring the luminescence signal. Recent developments in closed BPE array-based EFC and ECL sensing and imaging are summarized and discussed in detail. Finally, we consider the challenges and opportunities for improving the spatial resolution of closed BPE array-based electrochemical imaging, and emphasize the important application of this technique to the imaging of cellular activities at the single-cell level.

Electrically Amplified Circularly Polarized Luminescence by a Chiral Anion Strategy.

The development of circularly polarized electroluminescence (CPEL) is currently hampered by the high difficulty and cost in the syntheses of suitable chiral materials and the notorious chirality diminishment issue in electrical devices. Herein, diastereomeric IrIII and RuII complexes with chiral (±)-camphorsulfonate counteranions are readily synthesized and used as the active materials in circularly polarized light-emitting electrochemical cells to generate promising CPELs. The addition of the chiral ionic liquid (±)-1-butyl-3-methylimidazole camphorsulfonate into the active layer significantly improves the device performance and the electroluminescence dissymmetry factors (≈10-3 ), in stark contrast to the very weak circularly polarized photoluminescence of the spin-coated films of these diastereomeric complexes. Control experiments with enantiopure IrIII complexes suggest that the chiral anions play a dominant role in the electrically-induced amplification of CPELs.

Study on Ammonia Content and Distribution in the Microenvironment Based on Covalent Organic Framework Nanochannels.

A crack-free micrometer-sized compact structure of 1,3,5-tris(4-aminophenyl)benzene-terephthaldehyde-covalent organic frameworks (TAPB-PDA-COFs) was constructed in situ at the tip of a theta micropipette (TMP). The COF-covered theta micropipette (CTP) then created a stable liquid-gas interface inside COF nanochannels, which was utilized to electrochemically analyze the content and distribution of ammonia gas in the microenvironments. The TMP-based electrochemical ammonia sensor (TEAS) shows a high sensing response, with current increasing linearly from 0 to 50,000 ppm ammonia, owing to the absorption of ammonia gas in the solvent meniscus that connects both barrels of the TEAS. The TEAS also exhibits a short response and recovery time of 5 ± 2 s and 6 ± 2 s, respectively. This response of the ammonia sensor is remarkably stable and repeatable, with a relative standard deviation of 6% for 500 ppm ammonia gas dispensing with humidity control. Due to its fast, reproducible, and stable response to ammonia gas, the TEAS was also utilized as a scanning electrochemical microscopy (SECM) probe for imaging the distribution of ammonia gas in a microspace. This study unlocks new possibilities for using a TMP in designing microscale probes for gas sensing and imaging.

Porcine oviductal extracellular vesicles facilitate early embryonic development via relief of endoplasmic reticulum stress.

The key to successful in vitro embryo production (IVEP) is to mimic the natural in vivo oviductal microenvironment. Although the chemically defined media in extensive use for the in vitro culture of mammalian embryos is based on the composition of oviductal fluid, the IVEP systems in current use must still bypass the oviduct to produce embryos in vitro. Extracellular vesicles (EVs) in the oviduct are versatile intercellular delivery vehicles for maternal-embryo communication, and a lack of them can be associated with failed early embryonic development under in vitro culture conditions. Herein, we isolated EVs from porcine oviduct fluid and confirmed that oviductal EV supplementation improves the embryonic development of parthenogenetically activated (PA) embryos in terms of blastocyst formation rates and total cell numbers. Our experiments also revealed that a beneficial effect of oviductal EVs on PA embryos was achievable, at least in part, by relieving endoplasmic reticulum stress. These results suggest that the maternal-embryo communication mediated by oviductal EVs benefits early embryonic development. Given the contribution of oviductal EVs to early embryonic development, these findings offer novel insights for the optimization of current IVEP systems.

Organoplatinum(II) Cruciform: A Versatile Building Block to Fabricate 2D Microcrystals with Full-Color and White Phosphorescence and Anisotropic Photon Transport.

Conventional square-planar platinum complexes typically form one-dimensional assemblies as a result of unidirectional metallophilic and/or π⋅⋅⋅π intermolecular interactions. Organoplatinum(II) complexes with a cruciform shape are presented herein to construct two-dimensional (2D) microcrystals with full-color and white phosphorescence. These 2D crystals show unique monocomponent π⋅⋅⋅π stacking, from either the cyclometalating or noncyclometalating ligand, and the bicomponent alternate π⋅⋅⋅π stacking from both ligands along different facet directions. Anisotropic tri-directional waveguiding is further implemented on a single hexagonal microcrystal. These results demonstrate the great capability of the organoplatinum(II) cruciform as a general platform to fabricate 2D phosphorescent micro-/nanocrystals for advanced photonic applications.

Selective, Anisotropic, or Consistent Polarized-Photon Out-Coupling of 2D Organic Microcrystals.

Nano- and micromaterials with anisotropic photoluminescence and photon transport have widespread application prospects in quantum optics, optoelectronics, and displays. But the nature of the polarization information of the out-coupled light, with respect to that of the source luminescence, has never been explored in active optical-waveguiding organic crystals. Herein, three different modes (selective, anisotropic, and consistent) of polarized-photon out-coupling are proposed and successfully implemented in a set of 2D organic microcrystals with highly linearly-polarized luminescence. It is found that the polarization direction and degree of the luminescence out-coupled through different waveguiding channels can either be essentially retained or distinctly changed with respect to those of the original luminescence, depending on the molecular arrangement and the orientation of transition dipole moments of the crystal. This work demonstrates the promising potential of 2D emissive microcrystals in multi-channel polarized photon transport.

Light-Enhanced Osmotic Energy Harvester Using Photoactive Porphyrin Metal-Organic Framework Membranes.

High ion selectivity and permeability, as two contradictory aspects for the membrane design, highly hamper the development of osmotic energy harvesting technologies. Metal-organic frameworks (MOFs) with ultra-small and high-density pores and functional surface groups show great promise in tackling these problems. Here, we propose a facile and mild cathodic deposition method to directly prepare crack-free porphyrin MOF membranes on a porous anodic aluminum oxide for osmotic energy harvesting. The abundant carboxyl groups of the functionalized porphyrin ligands together with the nanoporous structure endows the MOF membrane with high cation selectivity and ion permeability, thus a large output power density of 6.26 W m-2 is achieved. The photoactive porphyrin ligands further lead to an improvement of the power density to 7.74 W m-2 upon light irradiation. This work provides a promising strategy for the design of high-performance osmotic energy harvesting systems.

Barcode signal amplifying strategy for sensitive and accurate protein detection on LC-MS/MS.

Protein drugs showing strong pharmaceutical activity, high specificity, and low toxicity and side effects have drawn extensive attention in the field of life sciences and medicine. Precise evaluation of the function of these drugs requires accurate and sensitive detection methods. Here, we report a novel chromatography-tandem mass spectrometry (LC-MS/MS) method for sensitive and selective detection of protein drugs. Magnetic nanoparticles (Apt29@MNPs) were functionalized by thrombin aptamers, and quantum dots (Apt15@ss@QDs) were dual-functionalized with quantitative thrombin aptamers and small molecules with high ionization efficiency as the mass barcode. After Apt29@MNPs specifically purify and enrich thrombin from biological samples, they can form a nano "sandwich structure" when Apt15@ss@QDs are added, resulting in the release of the mass barcode for LC-MS/MS analysis via the cutting of the disulfide bond. Since there is a higher quantitative molecular ratio of mass barcode to thrombin in the nano-"sandwich structure", quantitative detection of thrombin with high sensitivity and selectivity can be achieved via the LC-MS/MS detection of the mass barcode with high ionization efficiency rather than thrombin, which effectively avoids the disadvantages of direct protein detection by mass spectrometry. The established method for thrombin detection shows a good linear relationship in a concentration range of 0.00115-1.15 nM with a limit of detection (LOD) of 0.0007 nM. The present work provides a new approach for the effective and sensitive quantitative analysis of protein drugs and would be of great significance in promoting the development of protein drugs and clinical applications.

Full-Color and White Circularly Polarized Luminescence of Hydrogen-Bonded Ionic Organic Microcrystals.

A simple and general method is presented herein for the in situ preparations of circularly polarized luminescence (CPL)-active microcrystals with a large luminescence dissymmetry factor glum , high fluorescence quantum efficiency (ΦFL ), wide emission color tenability, and well-ordered morphology. The reactions of pyridine-containing achiral molecules 1-7 with chiral camphor sulfonic acid ((±)-CSA) gave crystalline microplates formed by hydrogen bonding interactions between the protonated pyridinium units and the sulfonic anions. The chiral information of CSA are effectively transferred to the microcrystals by hydrogen bonding to afford full-color CPL from deep-blue to red with glum in the order of 10-2 and ΦFL up to 80 %. Moreover, organic microcrystals with high-performance white CPL (ΦFL =46 %; |glum |=0.025) are achieved via the light-harvesting energy transfer between blue and yellow emitters.

Reversible Electrochemical Tuning of Ion Sieving in Coordination Polymers.

Membrane-based ion separation is environmentally friendly, energy-efficient, and easy to integrate, being widely used in water desalination and purification systems. With the existing separation technologies, it is yet difficult to achieve real time, in situ, and reversible control of the separation process. Here, we design and fabricate a Prussian blue (PB) coordination polymer based membrane with uniform and electrochemically size-tunable subnanopores. The ion separation can be significantly and reversibly modulated through the electrochemical conversion between PB and Prussian white (PW). The permeation rates of small hydrated metal ions (Cs+ and K+) obviously increase upon switching from PB to PW, while the permeation rates of large hydrated metal ions (Li+, Na+, Mg2+, and La3+) remain constant. The membrane selectivity of small hydrated ions to large hydrated ions can be increased by more than 2 times during the electrochemical switch, which could be assigned to the slightly larger crystal size (e.g., pore window size) of PW than PB. The present approach provides a new strategy for constructing tunable seawater desalination and ion extraction systems.

Fabrication of High-Density and Superuniform Gold Nanoelectrode Arrays for Electrochemical Fluorescence Imaging.

Nanoelectrode arrays have been widely used in electroanalytical applications. The challenge is to develop low-cost and simple approaches to the fabrication of superuniform and ultrasmall nanoelectrode arrays for improving analytical performance and imaging resolution. Here, superuniform and high-density gold nanoelectrode arrays with tunable electrode diameters and interelectrode distances have been fabricated by electrodeposition, followed by a simple mechanical polishing process. The fabricated free-standing arrays have a high density (108 cm-2) of nanoelectrodes (60, 140, and 200 nm in diameter), and can be used as closed bipolar electrode arrays to image electrochemical heterogeneity with micrometer spatial resolution. With the help of a confocal microscope, individual nanoelectrodes can be visualized and resolved from the reflected light. Thus, the nanoelectrode arrays are promising in electrochemical imaging with high spatial resolution.

[Network pharmacology research and experimental validation of "Coptidis Rhizoma-Pinelliae Rhizoma" in treating gastric carcinoma].

To investigate the mechanism of Coptidis Rhizoma-Pinelliae Rhizoma in the treatment of gastric cancer based on syste-matic pharmacology and data mining. The chemical constituents of Coptidis Rhizoma and Pinelliae Rhizoma were obtained from Traditio-nal Chinese Medicine Systems Pharmacology Database(TCMSP) and Shanghai Institute of Organic Chemistry database of Chinese Academy of Sciences by data mining. Then the active ingredients were screened by ADME, and the targets of the active ingredients were predicted by chemometrics. Molecular docking and free energy analysis were used to verify and screen the targets, so as to obtain the therapeutic targets of Coptidis Rhizoma and Pinelliae Rhizoma for gastric cancer. The biological functions, diseases and related signal pathways corresponding to the targets were further analyzed, and then the multi-component, multi-target and multi-channel mechanism of Coptidis Rhizoma and Pinelliae Rhizoma for gastric cancer were elaborated. Finally, MTT, Scratch, Transwell and Western blot experiments were carried out to verify the inhibitory effect of Coptidis Rhizoma and Pinelliae Rhizoma on human gastric cancer cell line MKN-45. A total of 46 active ingredients of Coptidis Rhizoma and Pinelliae Rhizoma were screened, as well as 77 corresponding targets, 38 targets related to gastric cancer and its complications, top 8 related signaling pathways, and top 20 target molecular functions by GO analysis. Cell experiments also proved that Coptidis Rhizoma and Pinelliae Rhizoma could effectively inhibit the proliferation, invasion and migration ability of gastric cancer cells and inhibit TGF-ß1-induced Wnt/ß-catenin signaling pathway activation. Coptidis Rhizoma and Pinelliae Rhizoma drug pair has many active ingredients, which can regulate nervous and mental system, cell cycle, cell differentiation and metastasis, and enhance anti-inflammatory and immune functions, playing a synergistic anti-cancer role in gastric cancer and its complications and providing new ideas for the follow-up clinical treatment of gastric cancer.

Exploring the Confinement Effect of Carbon Nanotubes on the Electrochemical Properties of Prussian Blue Nanoparticles.

A novel and efficient photochemical method has been proposed for the encapsulation of Prussian blue nanoparticles (PBNPs) inside the channels of carbon nanotubes (PB-in-CNTs) in an acidic ferrocyanide solution under UV/vis illumination, and the confinement effect of CNTs on the electrochemical properties of PBNPs is systematically explored. PB-in-CNTs show a faster electron-transfer process, an enhanced electrocatalytic activity toward the reduction of H2O2, and an increased anti-base ability compared to PBNPs loaded outside of CNTs (PB-out-CNTs). In addition, PB-in-CNTs show an increased electrochemical reversibility and an unexpected diameter-independent catalytic activity with the decrease of CNT diameters. The improved electrochemical properties of PB-in-CNTs are attributed to the modified electronic properties and dimensions of PBNPs induced by the confinement effect of CNTs. This work provides further insights into the confinement effect on the properties of nanomaterials and will inspire extensive relevant investigations in the development of novel composites or excellent catalysts.