Metal–Covalent Organic Frameworks Linked by Fe-Iminopyridine for Single-Atom Peroxidase-Mimetic Nanoenzymes

Metal–covalent organic frameworks (MCOFs) feature regular structures, adjustable pore channels, designable structures, and abundant tunable metal-catalytic active sites and are promising candidates for advanced single-atom enzymes. Here, we constructed porous and crystalline Fe-COFTAPB‑BPA linked with Fe-iminopyridine moieties from the corresponding building blocks under ambient conditions in the time scale of minutes. Fe-COFTAPB‑BPA with single-atom Fe dispersion could react with H2O2 to catalyze the oxidation of tetramethylbenzidine (TMB), demonstrating that an MCOF with a well-defined metallo ligand structure can function as a single-atom enzyme. Steady-state kinetic analysis showed that crystalline Fe-COFTAPB‑BPA revealed a higher affinity to TMB than amorphous Fe-PolyTAPB‑BPA at a similar Fe content attributed to its regular pore structure, higher specific surface area, and uniform distribution of catalytically active sites. As a peroxidase mimetic, Fe-COFTAPB‑BPA exhibits the advantages of easy preparation, good stability, and higher catalytic efficiency

Phase Equilibria and Phase Diagrams of Na⁺//F^–, CO₃^2–, PO₄^3–-H₂O Quaternary and Subsystems at 313.15 K

Rare-earth ore concentrate is calcined at high temperature by the alkaline method, and the associated elements fluorine and phosphorus are enriched in the form of sodium fluoride and sodium phosphate in water elution. To separate and recover fluorine and phosphorus from the aqueous solution, the solid–liquid equilibrium behaviors of the quaternary systems Na+//F–, CO32–, PO43–-H2O and their two sub-ternary systems NaF-Na3PO4-H2O and Na2CO3-Na3PO4-H2O at 313.15 K were studied via the isothermal solubility phase equilibrium method. Solubility data, liquid density and pH, two complete isothermal phase diagrams of the ternary system, and one complete isothermal phase diagram of the quaternary system were obtained. The results showed that two double salts NaF·2Na3PO4·19H2O and Na3PO4·3Na2CO3·8H2O occurred in the respective ternary systems. Five solid species of one anhydrous salt of NaF, two hydrous salts of Na2CO3·H2O and Na3PO4·12H2O, and two double salts of Na3PO4·3Na2CO3·8H2O and NaF·2Na3PO4·19H2O were found in the quaternary system. The phase diagram of the quaternary system consisted of three invariant points, five crystallization regions, and seven univariate curves. Na3PO4 easily combined with NaF to form double salt NaF·2Na3PO4·19H2O, which occupied a larger phase region in the quaternary phase diagram. The increase in Na2CO3 will lead to the decrease in the solubility of Na3PO4 and NaF in the system

Portable Photoelectrochemical Device Integrated with Self-Powered Electrochromic Tablet for Visual Analysis

A portable photoelectrochemical (PEC) device is developed by intergating a self-powered electrochromic tablet for visual analysis. The tablet consists of an electron-injector (EI) part for photo-to-electric conversion and an electrochromic (EC) part for visualized readout, which are coated with dye-sensitized titanium dioxide film and Ni-doped tungsten trioxide (WO₃) film, respectively. Under the illumination of a white LED light, the photoexcited electrons generated from EI part convey to EC part through the conductive inner side of indium tin oxide slide and would cause color change of the Ni-doped WO₃ film in the presence of protons. Furthermore, the Ni-doped WO₃ film exhibits excellent transmittance modulation of more than 80%, providing an enhanced signal for visual analysis. Using pyrophosphate ion (PPi) as a model analyte, we have successfully constructed a visualized PEC sensing platform based on the formation of blue-colored hydrogen tungsten bronzes via the hydrolysis reaction of PPi. Being equipped with a small light source and a dark box, the PEC tablet as a portable device can perform colorimetric measurement with good reversibility and stability. This smart PEC device provides important reference for future studies on the visual application in practice

Stepwise Chemical Reaction Strategy for Highly Sensitive Electrochemiluminescent Detection of Dopamine

A stepwise chemical reaction strategy based on the specific recognition of boronic acid to diol, and <i>N</i>-hydroxysuccinimide (NHS) ester to amine group, was designed to construct a “signal on” electrochemiluminescence (ECL) platform for highly sensitive detection of dopamine. A boronic acid-functionalized pyrene probe was synthesized and was self-assembled on the sidewalls of carbon nanotubes via π–π stacking interactions as capture probes on a glassy carbon electrode. Meanwhile, 3,3′-dithiodipropionic acid di­(<i>N</i>-hydroxysuccinimide ester) (DSP)-functionalized CdTe quantum dots (QDs) were designed as signal probes and characterized with transmission electron microscopy and spectroscopic techniques. Upon stepwise chemical reaction of dopamine with boronic acid and then DSP-QDs, the QDs were captured on the electrode as ECL emitters for signal readout, leading to an ultralow background signal. By using O₂ as an endogenous coreactant, the “signal on” ECL method was employed to quantify the concentration of dopamine from 50 pM to 10 nM with a detection limit of 26 pM. Moreover, the stepwise chemical reaction-based biosensor showed high specificity against cerebral interference and was successfully applied in the detection of dopamine in cerebrospinal fluid samples. The stepwise chemical reaction strategy should be a new concept for the design of highly selective analytical methods for the detection of small biomolecules

Surface-Embedded Liquid Metal Electrodes with Abrasion Resistance <i>via</i> Direct Magnetic Printing

Gallium-based liquid metals (LMs) featuring both high conductivity and fluidity are ideal conductors for soft and stretchable electronics. However, their liquid nature is a double-edged sword in many key applications since LMs are inherently prone to mechanical damage. Although additional encapsulation is frequently used for the protection of delicate LM electrodes, it hinders the electrical interfacing with other objects for interconnection, sensing, and stimulation. Here, different from conventional patterning methods that deposit LM on or inside substrates, we for the first time report a simple strategy to create surface-embedded LM of eutectic gallium-indium (EGaIn) circuits with mechanical damage endurance. This was achieved by using direct magnetic printing to overcome the high surface tension of LM, allowing it to be passively filled into the laser-patterned microgrooves on soft substrates. We show that the surface-embedded LM circuits are resistant to mechanical erasure, washing, and peeling. We also show the applications of our surface-embedded LM electrodes in respiration monitoring and electrical stimulation of nerves. This work provides a simple and efficient way to create mechanically reliable LM microelectrodes, holding great promise for wearable and implantable bioelectronics

Surface-Embedded Liquid Metal Electrodes with Abrasion Resistance <i>via</i> Direct Magnetic Printing

Gallium-based liquid metals (LMs) featuring both high conductivity and fluidity are ideal conductors for soft and stretchable electronics. However, their liquid nature is a double-edged sword in many key applications since LMs are inherently prone to mechanical damage. Although additional encapsulation is frequently used for the protection of delicate LM electrodes, it hinders the electrical interfacing with other objects for interconnection, sensing, and stimulation. Here, different from conventional patterning methods that deposit LM on or inside substrates, we for the first time report a simple strategy to create surface-embedded LM of eutectic gallium-indium (EGaIn) circuits with mechanical damage endurance. This was achieved by using direct magnetic printing to overcome the high surface tension of LM, allowing it to be passively filled into the laser-patterned microgrooves on soft substrates. We show that the surface-embedded LM circuits are resistant to mechanical erasure, washing, and peeling. We also show the applications of our surface-embedded LM electrodes in respiration monitoring and electrical stimulation of nerves. This work provides a simple and efficient way to create mechanically reliable LM microelectrodes, holding great promise for wearable and implantable bioelectronics

Assembly of Reusable DNA Blocks for Data Storage Using the Principle of Movable Type Printing

Due to its high coding density and longevity, DNA is a compelling data storage alternative. However, current DNA data storage systems rely on the de novo synthesis of enormous DNA molecules, resulting in low data editability, high synthesis costs, and restrictions on further applications. Here, we demonstrate the programmable assembly of reusable DNA blocks for versatile data storage using the ancient movable type printing principle. Digital data are first encoded into nucleotide sequences in DNA hairpins, which are then synthesized and immobilized on solid beads as modular DNA blocks. Using DNA polymerase-catalyzed primer exchange reaction, data can be continuously replicated from hairpins on DNA blocks and attached to a primer in tandem to produce new information. The assembly of DNA blocks is highly programmable, producing various data by reusing a finite number of DNA blocks and reducing synthesis costs (∼1718 versus 3000 to 30,000 US$ per megabyte using conventional methods). We demonstrate the flexible assembly of texts, images, and random numbers using DNA blocks and the integration with DNA logic circuits to manipulate data synthesis. This work suggests a flexible paradigm by recombining already synthesized DNA to build cost-effective and intelligent DNA data storage systems

Oriented Two-Dimensional Covalent Organic Framework Films for Near-Infrared Electrochromic Application

The electrochromic property and device construction of a triphenylamine-based oriented two-dimensional covalent organic framework (2D COF) film on indium tin oxide (ITO) coated glass was reported. The characterization of the 2D COF3PA‑TT film revealed that the film was uniform, with good crystallinity, and oriented with its 2D plane parallel to the substrate. For the first time, the electrochromic properties of 2D COF3PA‑TT film were studied. 2D COF3PA‑TT film on ITO exhibited reversible color transition between deep red and dark brown during redox process. Spectroelectrochemical experiments revealed color changes in the absorption spectra of 2D COF3PA‑TT film in the visible and near-infrared regions and showed the characteristics of intervalence charge transfer. The quasi-solid-state electrochromic device was prepared based on the COF3PA‑TT film, and it exhibited moderate performance and stability in the near-infrared region

DataSheet_1_Identification of a Novel SBP1-Containing SCFSFB Complex in Wild Dwarf Almond (Prunus tenella).docx

S-RNase-based gametophytic self-incompatibility (SI), in which specificities of pistil and pollen are determined by S-RNase and the S locus F-box protein, respectively, has been discovered in the Solanaceae, Plantaginaceae, and Rosaceae families, but some underlying molecular mechanisms remain elusive and controversial. Previous studies discovered SI in wild dwarf almond (Prunus tenella), and pistil S (S-RNase) and pollen S (SFB) determinant genes have been investigated. However, the SCF (SKP1–Cullin1–F-box-Rbx1) complex, which serves as an E3 ubiquitin ligase on non-self S-RNase, has not been investigated. In the current study, PetSSK1 (SLF-interacting-SKP1-like1), SBP1 (S-RNase binding protein 1), CUL1, and SFB genes (S-haplotype-specific F-box) were identified in an accession (ZB1) of P. tenella. Yeast two-hybrid assays revealed interactions between PetSBP1 and PetCUL1 and between PetSBP1 and PetSFBs (SFB16 and SFB17), and subsequent pull-down assays confirmed these interactions, suggesting a novel SBP1-containing SCFSFB complex in wild dwarf almond. Moreover, despite a putative interaction between PetSSK1 and PetCUL1, we revealed that PetSSK1 does not interact with PetSFB16 or PetSFB17, and thus the canonical SSK1-containing SCFSFB complex could not be identified. This suggests a novel molecular mechanism of gametophytic SI in Prunus species.</p