Transmembrane Ion Channels: From Natural to Artificial Systems.

Natural channel proteins allow the selective permeation of ions, water or other nutritious entities across bilayer membranes, facilitating various essential physiological functions in living systems. Inspired by nature, chemists endeavor to simulate the structural features and transport behaviors of channel proteins through biomimetic strategies. In this review, we start from introducing the inherent traits of channel proteins such as their crystal structures, functions and mechanisms.

Exciton-Exciton Interaction in Monolayer MoSe from Mutual Screening of Coulomb Binding.

Excitons in two-dimensional (2D) semiconductors are particularly exciting, as reduced screening and dimensional confinement foster their pronounced many-body interactions. Optical pumping is typically used to create excitons so as to study their properties, but at the same time such pumping can also create unbound charge carriers. This makes experimental determination of the exciton-exciton interactions difficult.

MTHFR C677T、MTHFR A1298C、MTRR A66G and MTR A2756G polymorphisms and male infertility risk: a systematic review and meta-analysis.

Background: Epidemiological studies have reported that polymorphisms of folate-metabolizing genes have a significant impact on male infertility. However, the results of published studies have come to different conclusions.

Objective: To determine an association between folate-metabolizing gene polymorphisms and the risk of male infertility.

Impact of insulin resistance on IVF/ICSI outcomes in women with polycystic ovary syndrome: A systematic review and meta-analysis.

Objective: To evaluate the effect of insulin resistance (IR) on in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) outcomes in patients with polycystic ovary syndrome (PCOS).

Study Design: PubMed, Google Scholar,Web of Science, Embase, Scopus and the Cochrane Library were searched to identify relevant studies. A total of 6,137 PCOS women undergoing IVF/ICSI with or without IR were included in the systematic review and meta-analysis.

Extracting double-quantum coherence in two-dimensional electronic spectroscopy under pump-probe geometry.

Two-dimensional electronic spectroscopy (2DES) can be implemented with different geometries, e.g., BOXCARS, collinear, and pump-probe geometries.

Molecular Motor-Driven Light-Controlled Logic-Gated K Channel for Cancer Cell Apoptosis.

Developing artificial ion transport systems, which process complicated information and step-wise regulate properties, is essential for deeply comprehending the subtle dynamic behaviors of natural channel proteins (NCPs). Here a photo-controlled logic-gated K channel based on single-chain random heteropolymers containing molecular motors, exhibiting multi-core processor-like properties to step-wise control ion transport is reported. Designed with oxygen, deoxygenation, and different wavelengths of light as input signals, complicated logical circuits comprising "YES", "AND", "OR" and "NOT" gate components are established.

Cross-phase modulation in two-dimensional spectroscopy.

Developing from transient absorption (TA) spectroscopy, two-dimensional (2D) spectroscopy with pump-probe geometry has emerged as a versatile approach for alleviating the difficulty in implementing 2D spectroscopy with other geometries. However, the presence of cross-phase modulation (XPM) in TA spectroscopy introduces significant spectral distortions, particularly when the pump and probe pulses overlap. We demonstrate that this phenomenon is extended to the 2D spectroscopy with pump-probe geometry and the XPM is induced by the interference of the two pump pulses.

Mechanical Properties, Radiation Resistance Performances, and Mechanism Insights of Nitrile Butadiene Rubber Irradiated with High-Dose Gamma Rays.

The radiation effect of materials is very important and directly related to the safety and reliability of nuclear reactors. Polymer materials, one of the indispensable materials in nuclear power equipment, must withstand the ordeal of high-energy ionizing rays. In this work, through screening different γ-ray dose irradiation conditions, we systematically and comprehensively study the changes in the structure and properties of nitrile butadiene rubber (NBR) before and after γ-ray static irradiation at a high dose rate, and master the rule and mechanism of the γ-ray static irradiation effect of these polymer materials.

Exosome-associated miRNA-99a-5p targeting BMPR2 promotes hepatocyte apoptosis during the process of hepatic fibrosis.

Liver fibrosis is a serious stage of chronic liver injury. Inhibition of hepatic stellate cells activation and hepatocytes apoptosis is important measures in the treatment of liver fibrosis. Studies have shown that exosomes are involved in regulating the information transmission between cells, but there are few studies on the interaction between exosomes from HSC and hepatocytes.

Light-controlled artificial transmembrane signal transduction for 'ON/OFF'-switchable transphosphorylation of an RNA model substrate.

Inspired by nature, it is of significant importance to design and construct biomimetic signaling systems to mimic natural signal transduction. Herein, we report an azobenzene/α-cyclodextrin (α-CD)-based signal transduction system with three functional modules: a light-responsive headgroup, lipid-anchored group, pro-catalyst tailgroup. The transducer can be inserted into the vesicular membrane to trigger the transmembrane translocation of molecules under the activation of light, forming a ribonuclease-like effector site and leading to the transphosphorylation of the RNA model substrate inside the vesicles.

Crown Ether-Based Ion Transporters in Bilayer Membranes.

Bilayer membranes that enhance the stability of the cell are essential for cell survival, separating and protecting the interior of the cell from its external environment. Membrane-based channel proteins are crucial for sustaining cellular activities. However, dysfunction of these proteins would induce serial channelopathies, which could be substituted by artificial ion channel analogs.

Flexible Single-Chain-Heteropolymer-Derived Transmembrane Ion Channels with High K Selectivity and Tunable pH-Gated Characteristics.

A series of single-chain random heteropolymer (RHP)-derived artificial ion channels with both high K selectivity and controllable pH-gated behaviors were fabricated by a facile "one-pot" polymerization method. The benzo-18-crown-6 moieties appended on lateral chains of RHPs can form ion-permeable nanopores and transport K over Na through the lipid bilayers. The ion permeation selectivity was significantly enhanced by incorporating a cholesterol group to serve as a membrane anchor.

Supramolecularly regulated artificial transmembrane signal transduction for 'ON/OFF'-switchable enzyme catalysis.

An artificial signal transduction model with a supramolecular recognition headgroup, a membrane anchoring group, and a pro-enzyme catalysis endgroup was constructed. The transmembrane translocation of the transducer can be reversibly regulated by competitive host-guest complexations as an input signal to control an enzyme reaction inside the lipid vesicles.

Biocompatible Diselenide-Containing Protein Hydrogels with Effective Visible-Light-Initiated Self-Healing Properties.

Smart hydrogels are typical functional soft materials, but their functional and mechanical properties are compromised upon micro- or macro-mechanical damage. In contrast, hydrogels with self-healing properties overcome this limitation. Herein, a dual dynamic bind, cross-linked, self-healing protein hydrogel is prepared, based on Schiff base bonds and diselenide bonds.

Efficient Long-Range Triplet Exciton Transport by Metal-Metal Interaction at Room Temperature.

Efficient and long-range exciton transport is critical for photosynthesis and opto-electronic devices, and for triplet-harvesting materials, triplet exciton diffusion length ( ) and coefficient ( ) are key parameters in determining their performances. Herein, we observed that Pt and Pd organometallic nanowires exhibit long-range anisotropic triplet exciton L of 5-7 μm along the M-M direction using direct photoluminescence (PL) imaging technique by low-power continuous wave (CW) laser excitation. At room temperature, via a combined triplet-triplet annihilation (TTA) analysis and spatial PL imaging, an efficient triplet exciton diffusion was observed for the Pt and Pd nanowires with extended close M-M contact, while is absent in nanowires without close M-M contact.

Unimolecular Helix-Based Transmembrane Nanochannel with a Smallest Luminal Cavity of 1 Å Expressing High Proton Selectivity and Transport Activity.

Natural protein channels have evolved with exquisite structures to transport ions selectively and rapidly. Learning from nature to construct biomimetic artificial channels is always challenging. Herein we present a unimolecular transmembrane proton channel by quinoline-derived helix, which exhibited highly selective and ultrafast proton transport behaviors.

Asymmetric Non-Fullerene Small-Molecule Acceptors toward High-Performance Organic Solar Cells.

Applying an asymmetric strategy to construct non-fullerene small-molecule acceptors (NFSMAs) in organic solar cells (OSCs) plays a vital role in the development of organic photovoltaic materials. In the past several years, taking advantage of the larger dipole moment and stronger intermolecular interactions, asymmetric NFSMAs have witnessed tremendous progress in OSCs with a power conversion efficiency of over 18%. From a structural point of view, besides the possible changes in the conformation effect on molecular packing, asymmetric acceptors can also achieve a balance between the solubility and the crystallinity.

The complete chloroplast genome sequence of (Elaeocarpaceae).

F. B. Forbes and Hemsl is an evergreen tree native to East Asia.

Biomimetic Cascade Polymer Nanoreactors for Starvation and Photodynamic Cancer Therapy.

The selective disruption of nutritional supplements and the metabolic routes of cancer cells offer a promising opportunity for more efficient cancer therapeutics. Herein, a biomimetic cascade polymer nanoreactor (GOx/CAT-NC) was fabricated by encapsulating glucose oxidase (GOx) and catalase (CAT) in a porphyrin polymer nanocapsule for combined starvation and photodynamic anticancer therapy. Internalized by cancer cells, the GOx/CAT-NCs facilitate microenvironmental oxidation by catalyzing endogenous HO to form O, thereby accelerating intracellular glucose catabolism and enhancing cytotoxic singlet oxygen (O) production with infrared irradiation.

Template-Free Self-Assembly of Two-Dimensional Polymers into Nano/Microstructured Materials.

In the past few decades, enormous efforts have been made to synthesize covalent polymer nano/microstructured materials with specific morphologies, due to the relationship between their structures and functions. Up to now, the formation of most of these structures often requires either templates or preorganization in order to construct a specific structure before, and then the subsequent removal of previous templates to form a desired structure, on account of the lack of "self-error-correcting" properties of reversible interactions in polymers. The above processes are time-consuming and tedious.

Many-Body Effect on Optical Properties of Monolayer Molybdenum Diselenide.

Excitons in monolayer transition metal dichalcogenides (TMDs) provide a paradigm of composite Boson in a two-dimensional system. This Letter reports a photoluminescence and reflectance study of excitons in monolayer molybdenum diselenide (MoSe) with electrostatic gating. We observe the repulsive and attractive Fermi polaron modes of the band edge exciton, its excited state, and the spin-off excitons, which the simple three-particle trion model is insufficient to explain.

Foldamer-Based Potassium Channels with High Ion Selectivity and Transport Activity.

Small molecules that independently perform natural channel-like functions show greatly potential in the treatment of human diseases. Taking advantage of aromatic helical scaffolds, we develop a kind of foldamer-based ion channels with lumen size varying from 3.8 to 2.

Hybrid Helical Polymer Nanochannels Constructed by Combining Aromatic Amide and Pyridine-Oxadiazole Structural Sequences.

An effective method is reported to synthesize aromatic helical polymer nanochannels by combining both the well-studied aromatic amide helical codons with pyridine-oxadiazole helical codons into helical structure sequences. With this strategy, a type of helical polymer nanochannel that shows structure-directed transmembrane transport functions is synthesized. Although such nanochannels show relatively weak selectivity for the transportation of alkali metal ions, accessible chemical mutation of helical structure sequences will provide a great chance for the design of desired channel property.

Reversible Ligand-Gated Ion Channel via Interconversion between Hollow Single Helix and Intertwined Double Helix.

Ligand responsiveness is one of the typical mechanisms in biological organization to trigger sophisticated channel switching. Here, we report a new type of helical trimer which can undergo transition between a hollow single helix and an intertwined double helix with no cavity by complexation and decomplexation of Cu ions. In addition, the one dimensional (1D) hollow helical tubes spontaneously generated from single helices via π-π interactions embedded into the lipid bilayers and displayed satisfactory channel stability and efficiency.

Light-responsive vesicles for enantioselective release of chiral drugs prepared from a supra-amphiphilic M-helix.

A kind of light-responsive vesicle was prepared by aqueous self-assembly of α-CD and an azobenzene-containing M-helical foldamer, which displayed dynamic disassembly-reassembly structural transformation when alternately irradiated by UV and visible light. Distinctively, this vesicle also exhibited enantioselective release abilities toward racemic propranolol (a β-blocker), owing to the M-helical building blocks.