Latest ArticlesMany evolved biomolecular functions such as ion pumping or redox catalysis rely on controlled charge transport through the polypeptide matrix, which can be regulated by shifts in molecular protonation states and dependent supramolecular packing modes in response to environmental cues. However, the exact roles of such dynamic, non-covalent interactions in peptide charge transport have remained elusive. To tackle this challenge, here we report the modulation of charge transport in a series of lysine (Lys)-substituted hepta-glycine (Gly) peptide self-assembled monolayers (SAMs) on template-striped gold (AuTS) bottom electrodes with eutectic gallium-indium (EGaIn) liquid metal top electrodes. We demonstrate systematic modulation of hydrogen bonding and more general electrostatic interactions by shifting the position of the charged Lys-residue and creating different protonation patterns by changing the environmental pH in the AuTS/peptide//GaOx/EGaIn junctions. The effective modulation is evidenced by current density–voltage (J-V) measurements combined with SAM characterization using ultraviolet photoelectron spectroscopy (UPS) and angle-resolved X-ray photoelectron spectroscopy (ARXPS), polarization modulation–infrared reflection-absorption spectroscopy (PM-IRRAS), and molecular dynamics (MD) simulations. Decreasing the hydrogen bonding inside the peptide SAMs and increasing the electrostatic interactions by environmental counterions amplifies the charge transport differently with Lys-position, which means that the sensitive electrical response of peptide SAMs can be tuned by the peptide sequence. Our results provide insights into the relationship between molecular design and in situ modulation of charge transport properties for the development of bionanoelectronics.
Understanding phase transitions in multi-component crystals is of importance for regulating specified functional materials. Herein, we present two new organic-inorganic hybrid crystals, (Me3NCH2CH2X)4[Ni(NCS)6] (X = Cl and Br), revealing distinct phase transitions. Specifically, the Cl-substituted cations weakly interact with discrete inorganic part hence reveal step-wise dynamic changes upon heating, which result in multi-step solid-solid phase transitions (P1-P21/n–A2/a–Cmce) including a ferroelastic one with a spontaneous strain of 0.0475. Whereas the Br-substituted cations with larger steric effect prevent the solid-solid phase transition but give a solid-liquid phase transition at above 419 K. The present instances well demonstrate the complicity for multi-component crystals arising from the delicate balance established by abundant weak intermolecular interactions, and inspire the design of novel phase-transition materials by judiciously assembling multi-component crystals.
Although many plasmonic nanosenosrs have been established for the detection of mercury(Ⅱ) (Hg2+), few of them is feasible for analyzing natural samples with very complex matrices because of insufficient method selectivity. To address this challenge, we propose an epitaxial and lattice-mismatch approach to the synthesis of a unique Au/Ag2S dimeric nanostructure, which consists of an Au segment with excellent plasmonic characteristics, and a highly stable Ag2S portion with minimum solubility product (Ksp(Ag2S) = 6.3 × 10−50). The detection relies on the chemical conversion of Ag2S to HgS when reacting with Hg2+, resulting in a red shift in the absorption band of the connecting Au NPs. The concurrent color changes of the solution from gray purple to dark green and finally to navy correlate well with Hg2+ concentration, thus enables UV–vis quantitation and a naked-eye readout of the Hg2+ concentration. This method exhibits superior selectivity towards Hg2+ over other interfering ions tested because Hg2+ is the only ion that can react with Ag2S to form HgS with even smaller solubility product (Ksp(HgS) = 4 × 10−53). The detection limit of this method is 1.21 µmol/L, calculated by the signal-to-noise of 3. The practicability of the method was verified by analyzing the Hg2+ in sewage water samples without sample pretreatment with satisfactory recoveries (93.1%-102.8%) and relative standard deviations (1.38%-2.89%). We believe this method holds great potential for on-the-spot detection of Hg2+ in environmental water samples with complex matrices.
Three sandwich-like [Ln2Fe2(B-α-FeW9O34)2]10− clusters (Ln2Fe4, Ln = Dy (1), Ho (2), and Y (3)) were obtained by reacting Na9[B-α-SbW9O33], Ln2O3, FeCl3·6H2O and KH2PO4. The [B-α-FeW9O34]11− units were formed via the in situ conversion of lacunary polyoxometalates (POM) [B-α-SbW9O33]9− and the Ln3+ ions were generated from the slow dissolution of Ln2O3, both of which play important roles in the synthesis of Ln2Fe4. Ln2Fe4 is the first 3d-4f cluster assembled from d-metal heteroatom-containing POM. The Dy2Fe4 cluster exhibits single-molecule magnet properties with an 80 K energy barrier in an optimal DC field. Cyclic voltammetry tests and controlled-potential coulometry experiments show that the polyoxometalate Fe heteroatom in clusters 1–3 is also electrochemically active.
The on-purpose direct propane dehydrogenation (PDH) has received extensive attention to meet the ever-increasing demand of propylene. In this work, by means of density functional theory (DFT) calculations, we systematically studied the intrinsic coordinating effect of Fe single-atom catalysts in PDH. Interestingly, the N and P dual-coordinated single Fe (Fe-N3P-C) significantly outperform the Fe-N4C site in catalysis and exhibit desired activity and selectivity at industrial PDH temperatures. The mechanistic origin of different performance on Fe-N3P-C and Fe-N4C has been ascribed to the geometric effect. To be specific, the in-plane configuration of Fe-N4 site exhibits low H affinity, which results in poor activity in CH bond activations. By contrast, the out-of-plane structure of Fe-N3P-C site exhibits moderate H affinity, which not only promote the CH bond scission but also offer a platform for obtaining appropriate H diffusion rate which ensures the high selectivity of propylene and the regeneration of catalysts. This work demonstrates promising applications of dual-coordinated single-atom catalysts for highly selective propane dehydrogenation.
There is no clear consensus regarding how cells respond to hydrostatic pressure. This is largely attributable to the high heterogeneity among cell types and the diverse custom-made devices used in previous studies. The aim of this work was to develop a facile device that could mimic various pressure environments and then delineate the cellular response to pressure stimulus. The device described here achieved both stable and periodic pressurization without oxygen deprivation. The biological utility of the device was assessed using human umbilical vein endothelial cells. We found more stereoscopic nuclear morphology and re-distribution of lamin A/C under high hydrostatic pressure compared to control cells. Mass spectrometry-based proteomics analysis showed significant changes in mitochondria-related pathways. Western blot analysis confirmed that high hydrostatic pressure induced a tendency toward mitochondrial fusion. Increased mitochondrial activity was observed as well. In conclusion, this device can be readily applied in biological research and extend our understanding of cellular mechano-sensation and the associated changes in mitochondrial behaviors.
Herein, we report a new metal-organic framework with an AIE ligand (H4TCPP = 2,3,5,6-tetra-(4-carboxyphenyl)pyrazine) and Mg2+ ions, that is, [Mg2(H2O)4TCPP]·DMF·5CH3CN (Mg-TCPP, TCPP = tetra-(4-carboxyphenyl)pyrazine) for detection of nitroaromatic explosives. Due to the coordination effect and restricted intramolecular rotation, Mg-TCPP exhibits bright blue light. As a fluorescent sensor, Mg-TCPP exhibits high selectivity and sensitivity for sensing 2,4,6-trinitrophenol (TNP) by quenching behaviors with the Stern-Volmer quenching constant (KSV) of 3.63×105 L/mol and achieves the low limit of detection of 25.6 ppb, which is beyond most of the previously reported fluorescent materials. Notably, the portable Mg-TCPP films are prepared and it can be used for rapid and sensitive TNP detection in a variety of environments including organic solvent and aqueous solution. Moreover, TNP vapor can be detected within 3 min by naked eye and the film could be regenerated under simple solvent cleaning.
Accurate detection and imaging of adenosine triphosphate (ATP) expression levels in living cells is of great value for understanding cell metabolism, physiological activities, and pathologic mechanisms. Here, we developed a DNA tetrahedron-based split aptamer probe (TD probe) for ratiometric fluorescence imaging of ATP in living cells. The TD probe is constructed by hybridizing two split ATP aptamer probes (Apt-a and Apt-b) to a DNA tetrahedron assembled by four DNA oligonucleotides (T1, T2, T3 and T4). In the presence of ATP, the TD probe will alter its structure from the open to closed state, thus bringing the separated donor and acceptor fluorophores into close proximity for high fluorescence resonance energy transfer (FRET) signals. The TD probe exhibits low cytotoxicity, efficient cell internalization and good biological stability. Moreover, based on the FRET "off" to "on" signal output mode, the TD probe can effectively avoid false-positive signals from complex biological matrices, which is significant for long-term reliable imaging in living cells. In addition, by changing the split aptamers attached to DNA tetrahedron, the proposed strategy may be extended for detecting various intracellular targets. Collectively, this strategy provides a valuable sensing platform for biomarkers analysis in living cells, thus having great potential for early clinical diagnosis and therapeutic evaluation.
In-situ monitoring of neurochemicals is of vital importance for the understanding of brain functions. Microelectrode-based photoelectrochemical (PEC) sensing has emerged as a promising tool for in vivo analysis since it inherits the merits of both optical and electrochemical methods. However, the in-situ excitation of photoactive materials on the photoelectrode in living body is still a challenge because of limited tissue penetration depth of light. To circumvent this problem, we herein developed an implantable optical fiber (OF)-based microelectrode for in vivo PEC analysis. The working electrode was constructed by coating Au film as conducting layer and CdS@ZnO as photoactive material on a micron-sized OF, which was free of the limitation of light penetration in biological tissues. Further decoration of an anti-biofouling layer on the surface made the sensor robust in biosamples. It was successfully applied for monitoring Cu2+ level in three different brain regions in the rat model of cerebral ischemia/reperfusion.
Metal-organic frameworks (MOFs) with large specific surface area, considerable pore volume, controllable structure, and high concentration of active metal sites have been applied widely in researches like catalysis and sensing. However, potential applications of MOFs in both photocatalysis and luminescence sensors are facing major challenges arising from their severe charge recombination, low utilization of solar energy, low quantum yield, limited charge transfer between the metal ions/clusters and the ligand. Recent studies revealed that rational introduction of carbon dots (CDs) with excellent optical properties, unique quantum confinement and high conductivity can greatly enhance the functions of MOFs. In this paper, typical synthesis methods of these CD-MOF composites as well as their potential applications in photocatalysis and sensing are reviewed with emphasis. Representative examples of these CD-MOF composites are discussed, and key features and advantages of CD-MOF composites that will facilitate future applications are highlighted.
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62199257
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
