Latest ArticlesIt remains a big challenge to develop solid-state stimuli-responsive materials for time-dependent information encryption and inkless erasable printing with long retention times. Herein, a 2D Cu2I2-based MOF with photoresponsive spiropyran (SP) groups orderly installed on its skeleton is developed. The structural isomerization from SP to colored merocyanine (MC) form can be triggered by removing the CH3CN guests. Besides, the degree of structural isomerization and the retention time can be adjusted by controlling the amount of CH3CN guests, exhibiting dynamic photochromic behavior with multicolor states and tunable retention time. Based on these advantages, time-dependent information encryption is successfully achieved. Furthermore, the long retention time (> 72 h) of the MC form under daylight conditions in the CH3CN-removed Cu2I2-based MOF and good repeatability make it promising in various applications, such as temporary calendars, price-cards, billboards, and reusable identity cards. This work provides a novel design strategy to fabricate multi-functional MOF-based smart materials for challenging applications of time-dependent information encryption and inkless erasable printing.
Tuberculosis (TB) is a chronic infectious disease, which is caused by the pathogen Mycobacterium tuberculosis (Mtb) and reemerged as a global health risk with a significant proportion of multi-drug resistant and extensively drug resistant TB cases. It is very urgent to find some novel high-confidence drug targets in Mtb for discovering the effective anti-TB agents. Thioredoxin reductase (TrxR) has been identified to be a highly viable target for anti-TB drugs for its important role in protecting the pathogen from thiol-specific oxidizing stress, regulating intracellular dithiol/disulfide homeostasis and DNA replication and repair. In the present work, a near-infrared (NIR) fluorescent probe DDAT was developed for the detection of TrxR activity and used to high-throughput screen the TrxR inhibitors from natural products. Two screened TrxR inhibitors from Sappan Lignum and microbial metabolites that were further used to inhibit Mycobacterium tuberculosis. All the results indicate that DDAT is a practical fluorescent molecular tool for the discovery of potential anti-TB drugs.
The lithium (Li) metal batteries (LMBs) are considered one of the most promising next-generation batteries due to its extremely high theoretical specific capacity. However, there are a couple of issues, e.g., the serious side reactions that occurred at the solid-liquid interface between the electrolyte and Li metal anode, hindering the broad commercialization of LMBs. Thus, a comprehensive understanding of the mechanisms underlying the decomposition of electrolytes is crucial to the design of LMBs. Herein, we utilize density functional theory simulations to explore the decomposition mechanism of electrolytes. The most commonly used ether electrolyte solvents, i.e., 1,2-dimethoxyethane (DME) and 1,3-dioxalane (DOL), based on suitable lithium salts, namely bis(trifluoromethanesulfonyl)imide (LiTFSI), are chosen to model the actual situations. We explicitly demonstrate that an electron-rich environment near the interface accelerates the decomposition of electrolytes. For ether electrolytes, we show that the LiTFSI degradation path is depending on the ratio of DOL to DME. In addition, the solvation structures of lithium-ion undergo a series of transformations upon electrolyte degradation, becoming thermodynamically more favorable and having a higher reduction potential in an electron-rich environment. Our finding provides new insights into the decomposition mechanisms of electrolytes and paves the way for the rational design of high-performance LMBs.
Lead-free double perovskite nanocrystals (NCs) have emerged as a promising candidate in the optical field, owing to their non-toxic, good moist heat and chemical stability. However, their poor optical properties limited their application. To improve the optical properties of lead-free double perovskite NCs, metal ion doping or alloying had been suggested as a promising strategy. Here, we prepared monodisperse, uniformly sized, cubic morphology of Cs2AgBiCl6 NCs with different Na+ incorporation amounts via a simple hot-injection method. The Na+ incorporation broke the parity-forbidden transition by reducing the inversion symmetry of the electron wave function at the Ag site, which changed the parity of the self-trapped exciton wave function and thus allowed radiative recombination. As a result, the photoluminescence quantum yield (PLQY) of Na+-alloyed Cs2AgBiCl6 NCs (12.1%) was higher than that of Cs2AgBiCl6 NCs (2.4%), and the exciton lifetime of Na+-alloyed Cs2AgBiCl6 NCs increased to 36.98 ns from 17.58 ns for Cs2AgBiCl6 NCs. By adjusting the amount of Na+ incorporation, the band gap of Cs2AgBiCl6 NCs can be significantly tuned from ~2.90 eV to ~3.50 eV. Furthermore, the temperature-dependent photoluminescence spectra indicated that the Na+-alloyed Cs2AgBiCl6 NCs possessed higher longitudinal optical phonon energy and exciton binding energy compared to Cs2AgBiCl6 NCs. This suggested that there were strong exciton-phonon interactions during exciton recombination, a reduced probability of non-radiative processes, and excellent thermal stability. It offers a promising strategy for improving the optical properties of lead-free double perovskite NCs, and have the potential to replace traditional lead halide perovskite NCs in future optoelectronic applications.
An inexpensive phosphine catalyst was used effectively for a transition-metal-free acyl-transfer of N-containing heteroaryl ketones for the rapid synthesis of N-fused heterocycles. The key pre-aromatic spirocyclic intermediate initialized by the single electron transfer (SET) process of Togni's reagent Ⅱ promoted by the tertiary phosphine resulted in an intriguing and alternative tactic for the cleavage of C‒C bonds. By using inexpensive tertiary phosphine as the catalyst, this skeleton-reorganizing approach of N-containing heteroaryl ketones allows a streamlined assembly of complex N-fused heterocycles with broad functional group tolerance.
Peptide drugs are known for their high biological safety. However, compared with small molecule drugs, peptide drugs are easily oxidized and hydrolyzed as well as short in half-life. Herein, inspired by the long circulation of albumin in blood, we screened albumin binding peptides (ABPs) from a one-bead one-compound (OBOC) peptide library to increase the half-life of peptide drugs. Beads displaying random peptides were screened using fluorescent labeled human serum albumin. Fluorescent beads with specific binding to albumin were isolated for sequencing. The selected ABPs can effectively bind to albumin, thus possessing the long circulation of albumin. The dissociation constant (KD) of ABPs to albumin is up to 1 × 10−8 mol/L. Once one of ABPs (ABP2) was coupled to triptorelin, the circulation half-life of triptorelin in mice was significantly prolonged to 263.50 h much longer than that of triptorelin alone (179.07 h). In addition, the combination therapy using ABP-conjugated triptorelin and doxorubicin (DOX) can effectively inhibit the proliferation of tumor cells in mice. The OBOC screening strategy and resulting ABPs showed great potential for enhancing the delivery efficiency of peptide drugs.
Traditional photosensitizers show limited singlet oxygen generation in hypoxic infection lesions, which greatly suppress their performance in antibacterial therapy. Meanwhile, there still is lack of feasible design strategy for developing hypoxia-overcoming photosensitizers agents. Herein, radical generation of π-conjugated small molecules is efficiently manipulated by an individual selenium (Se) substituent. With this strategy, the first proof-of-concept study of a Se-anchored oligo (thienyl ethynylene) (OT-Se) with high-performance superoxide radical (O2•−) and hydroxyl radical (•OH) generation capability is present, and achieves efficient antibacterial activities towards the clinically extracted multidrug-resistant bacteria methicillin-resistant S. aureus (MRSA) and carbapenem-resistant E. coli (CREC) at sub-micromolar concentration under a low white light irradiation (30 mW/cm2). The water-dispersible OT-Se shows a good bacteria-anchoring capability, biocompatibility, and complete elimination of multidrug-resistant bacteria wound infection in vivo. This work offers a strategy to boost type-Ⅰ photodynamic therapy (PDT) performance for efficient antibacterial treatments, advancing the development of antibacterial agents.
Developing new functional explosives that display high stability, good energy performance, and low sensitivity are one of the key directions of energetic materials research. In this work, two-dimensional (2D) Schiff-based energetic covalent organic frameworks (COFs) are prepared based on triaminoguanidine salts with different anions as building blocks. Benefiting from the robust covalent bond in 2D extended polygons and strong π-π interactions in the eclipsed interlayers, the synthesized energetic COFs showed higher thermal stability and lower mechanical sensitivity than their precursor salts. More importantly, incorporating triaminoguanidine salts into COFs effectively increase the corrosion resistance to metal under high humidity conditions, which is due to the imine moieties in COFs functioning as π acceptors and offering strong bonding with metallic ions. This work provides a new pathway for the development of high-performance energetic materials.
Urea plays a vital role in the sustainable development of mankind as it is one of the most important nitrogen fertilizers. Conventional synthesis of urea is accompanied by a high level of energy consumption while electrocatalytic methods suffer from low yields and poor selectivity. Our work achieves efficient synthesis of urea by designing the graphene-In2O3 electrocatalysts for the co-activated reduction of nitrate and carbon dioxide, where the formation rate of urea, Faraday efficiency (FE) and carbon selectivity at -0.35 V vs. RHE can reach 357.47 µg mg−1 h−1, 10.46% and ~100%, respectively. Herein, the key intermediates in the CN coupling reaction are demonstrated to be *NH2 and *CO2, which is of novelty compared to previous reports. This work may provide inspiration for subsequent studies on the reaction mechanism of the electrochemical synthesis of urea, as well as theoretical guidance for the sustainable synthesis of some other important chemical substances.
Monitoring α-glucosidase (α-Glu) activity is of great significance for the early diagnosis of type II diabetes. Here the blue fluorescent carbon dots (CDs) were integrated with two different recognizing molecules, β-cyclodextrin and phenylboronic acid, for assembling a multifunctional CDs (mCDs) nanoplatform for sensitively analyzing α-Glu and its inhibitors. The hydrolyzed product of 4-nitrophenyl-α-d-glucopyranoside (α-Glu substrate), p-nitrophenol, could efficiently quench the fluorescence of mCDs due to its cooperative molecular recognition with β-cyclodextrin and phenylboronic acid. The mCDs could be utilized for the detection of α-Glu activity with the limit of detection of 0.030 U/L. Moreover, the present α-Glu detection platform revealed a high selectivity, and other natural enzymes showed scarcely any effect on the present mCDs system. The proposed method could be facilely used to screen α-Glu inhibitors with satisfying performance. The rational mCDs is expected to supplement more comprehensive biosensing platforms for highly sensitive and specific recognition of disease-relevant biomarkers with clinical importance.
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