芯片毛细管电泳分离多种FITC衍生的氨基酸

用芯片毛细管电泳激光诱导荧光检测系统研究了分离多种荧光素异硫氰酸酯(FITC)衍生氨基酸的实验条件.采用以乙醇为有机添加剂的胶束毛细管电动色谱分离体系(50 mmol/LSDS,体积分数为15%的乙醇,5 mmol/L pH 9.2的硼砂缓冲液),在72 mm长的通道上实现了10种常见氨基酸的分离,一次分离的时间小于5 min.     

Attention-guided complex denoising network for automatic modulation recognition

With the rapid progress in artificial intelligence technology in recent years, deep learning has gradually become the main method in the field of radar signal automatic modulation recognition (AMR). Under harsh condition of lower signal–noise ratio (SNR), extracting the useful features of the noisy radar signal in the time or the time–frequency domain is extremely difficult because of serious noise corruption of the clean radar signals. Considering the complex-valued characteristic of radar signal, we propose an attention-guided complex denoising network (ACDNet) that consists of denoising and recognition modules. By utilizing the denoising module, we can estimate denoised signal in the noisy background, and thus the more distinctive features of the clean signal are extracted. The recognition module uses the extracted information to complete the modulation recognition task. Furthermore, squeeze-and-excitation blocks (channel attention mechanism) and the network are merged to guide the network to obtain more efficient performance. The experimental results demonstrate that ACDNet has obvious advantages over comparison deep learning algorithms at lower SNRs.     

Supramolecular Barrel-Rosette Ion Channel Based on 3,5-Diaminobenzoic Acid for Cation-Anion Symport

The structural tropology and functions of natural cation-anion symporting channels have been continuously investigated due to their crucial role in regulating various physiological functions. To understand the physiological functions of the natural symporter channels, it is vital to develop small-molecule-based biomimicking systems that can provide mechanistic insights into the ion-binding sites and the ion-translocation pathways. Herein, we report a series of bis((R)-(−)-mandelic acid)-linked 3,5-diaminobenzoic acid based self-assembled ion channels with distinctive ion transport ability. Ion transport experiment across the lipid bilayer membrane revealed that compound 1 b exhibits the highest transport activity among the series, and it has interesting selective co-transporting functions, i.e., facilitates K⁺/ClO₄⁻ symport. Electrophysiology experiments confirmed the formation of supramolecular ion channels with an average diameter of 6.2±1 Å and single channel conductance of 57.3±1.9 pS. Selectivity studies of channel 1 b in a bilayer lipid membrane demonstrated a permeability ratio of , , and indicating the higher selectivity of the channel towards KClO₄ over KCl salt. A hexameric assembly of a trimeric rosette of 1 b was subjected to molecular dynamics simulations with different salts to understand the supramolecular channel formation and ion selectivity pattern.     

An Artificial Single Molecular Channel Showing High Chloride Transport Selectivity and pH-Responsive Conductance

Inspired by the unique structure and function of the natural chloride channel (ClC) selectivity filter, we present herein the design of a ClC-type single channel molecule. This channel displays high ion transport activity with half-maximal effective concentration, EC₅₀, of 0.10 μM, or 0.075 mol % (channel molecule to lipid ratio), as determined by fluorescent analysis using lucigenin-encapsulated vesicles. Planar bilayer lipid membrane conductance measurements indicated an excellent Cl⁻/K⁺ selectivity with a permeability ratio P /P up to 12.31, which is comparable with the chloride selectivity of natural ClC proteins. Moreover, high anion/anion selectivity (P /P =66.21) and pH-dependent conductance and ion selectivity of the channel molecule were revealed. The ClC-like transport behavior is contributed by the cooperation of hydrogen bonding and anion–π interactions in the central macrocyclic skeleton, and by the existence of pH-responsive terminal phenylalanine residues.     

Synthetic Monosaccharide Channels: Size-Selective Transmembrane Transport of Glucose and Fructose Mediated by Porphyrin Boxes

Here we report synthetic monosaccharide channels built with shape-persistent organic cages, porphyrin boxes ( PB s), that allow facile transmembrane transport of glucose and fructose through their windows. PB s show a much higher transport rate for glucose and fructose over disaccharides such as sucrose, as evidenced by intravesicular enzyme assays and molecular dynamics simulations. The transport rate can be modulated by changing the length of the alkyl chains decorating the cage windows. Insertion of a linear pillar ligand into the cavity of PB s blocks the monosaccharide transport. In vitro cell experiment shows that PB s transport glucose across the living-cell membrane and enhance cell viability when the natural glucose transporter GLUT1 is blocked. Time-dependent live-cell imaging and MTT assays confirm the cyto-compatibility of PB s. The monosaccharide-selective transport ability of PB s is reminiscent of natural glucose transporters (GLUTs), which are crucial for numerous biological functions.