Latest ArticlesPeptide-drug conjugates (PDCs) composed of peptide, spacer and drug have gained extensive attention in the field of drug delivery owing to its precise control over the drug payload and architecture. However, the achievement of controllable and rapid drug release at targeted site by PDCs is still a great challenge for pharmaceutist. Herein, we introduced the histidine residue into PDCs to generate a supramolecular hydrogel via a pH-trigger strategy, which exhibited an autocatalytic effect to precisely tune drug release from PDCs hydrogel. Using indomethacin (Idm) as model drug, various PDCs (Y(Idm)EEH, Y(Idm)EEK and Y(Idm)EER) were synthesized and their self-assembling properties were investigated in terms of critical aggregation concentration (CAC), transmission electron microscopy (TEM) and rheometer. Introduction of histidine residue into PDCs presented a robust catalytic activity on the ester hydrolysis of p-nitrophenyl acetate in aqueous solution, as well conferred the autocatalytic capacity to hydrolyze the PDCs into active parent drug (Idm). Overall, we reported an autocatalytic activity of histidine residue to precisely tune drug release from PDCs hydrogels.
Regenerating spent graphite (SG) from retired lithium-ion batteries (LIBs) can effectively avoid resource waste. However, the technology is challenged by the impurity content and energy consumption. In this study, micro-expanded graphite (MEG) was synthesized by one-step oxidation method using waste LIBs anode graphite as material and perchloric acid as intercalation and oxidant agent. Then, its performance as a LIBs anode material were investigated as well as the greenhouse gas (GHG) emissions of the whole process were calculated. Perchloric acid was successfully embedded in the SG during the reaction, which effectively removed the impurities in the graphite. Defects introduced during intercalation and delamination, such as nanopores and intercrystalline cracks. Both provide additional space for Li ions during charging and discharging, thereby promoting capacity enhancement. The prepared MEG expresses a rate capability as high as 340.32 mAh/g at a current density of 0.1 C and still retains 81.73% of the capacity after 100 cycles at a current density of 1 C. Additionally, the GHG emissions of the synthesis process of this article and other literatures are compared. The results demonstrated that perchloric acid treatment process provides a low-carbon, time- and energy-saving approach for regenerated SG as battery grade material.
Compartmentalization in the biological world brings excellent efficiency and specificity to the formation of complex compounds, inspiring supramolecular chemists to continuously search for defined spaces that can mimic such natural binding sites. Bowl-shaped cavitands built up from resorcinarenes (RA) present rigid and preorganized concave surfaces, which are capable of mimicking the molecular recognition properties of enzymes. The versatile scaffold of RA endows the cavitand with terrific variety and excellent binding behavior. This review provides a comprehensive overview over the structural modification to date in the high attention field of RA-based cavitands development. Different strategies for synthesizing diverse cavitands, such as small cavity cavitands, wider cavity cavitands, deep cavity cavitands, biscavitands, and asymmetric cavitands, are discussed in details. Furthermore, insights into their applications including catalysis, separations and sensing are provided.
We report two air-stable nickel(Ⅱ) half-sandwich complexes, Cp*Ni(1,2-Cy2PC6H4O) (1) and Cp*Ni(1,2-Ph2PC6H4NH) (2), for cooperative B-H bond activation and their applications in catalytic hydroboration of unsaturated organic compounds. Both 1 and 2 react with HBpin by adding the B-H bond across the Ni−X bond (X = O or N), giving rise to the 18-electron Ni(Ⅱ)−H active species, [H1(Bpin)] and [H2(Bpin)]. Subtle tuning of the Ni−X pair and the supporting ancillary phosphine have a significant effect on the reactivity and catalytic performance of Cp*Ni(1,2-R2PC6H4X). Unlike [H2(Bpin)], the activation of HBpin in [H1(Bpin)] is reversible, which enables the Ni−O complex to be an effective cooperative catalyst in the hydroboration of N-heteroarenes, and as well as ketones and imines.
This report describes the oxidative cyclopalladation activation of a C≡C bond during the Pd-catalyzed hydroalkylation of alkynes and analyzes potential reaction pathways based on density functional theory calculations. The more favorable pathway in-volves an oxidative cyclopalladation to generate a palladacyclopropene intermediate, which is rarely examined in Pd-catalyzed alkyne transformations. The reaction pathway proposed herein is kinetically favorable relative to the commonly proposed alkyne insertion mode. Furthermore, the Laplacians of the electron density, interaction region indicators, Mayer bond orders, and localized orbital bonding are evaluated to determine the reaction processes and characterize the key intermediates. Theoretical calculations indicate covalent bonding between a Pd(Ⅱ) center and the two C-atoms in three-membered palladacycle species. Finally, electrostatic potential analysis reveals that the regioselectivity is governed by the charge distribution on the palladacycle moiety during the protonation step.
Heme responsible for the dioxygen fixation, transport and conversion is a metalloporphyrin complex highly dependent on its diverse geometry of ligand. In this work, a trans-ortho-di-strapped zinc porphyrin with dome-like deformation was synthesized by thermodynamically controlling the formation of trans-precursor of porphyrinogen. Its single-crystal structure demonstrated that the asymmetric treatment of porphyrin achieves three goals of creating two secondary coordination sphere (SCS) bulks, maintaining a unique dome deformation, and making atomic out-of-plane deviation. In this way, this metallic complex integrates at least three key features of the pocket structure, the differentiated axial ligations, and the ring distortion, making it an ideal heme analog.
Benefitting from the tunable heterogeneous interface and electronic interaction, metal-polymer-based hybrid composites have attracted wide attention. It is highly desired to develop advanced synthesis methodology and understand the structure-performance relationship. Herein, with the aniline oligomer as the key enabler, we resolve the inferior dynamics issue in the Ag+-aniline reaction system, and successfully fabricate a sub-micron anisotropic eccentric Ag@polyaniline (PANI) particle (an average size up to 340 nm) at room temperature. We demonstrate the synergy mechanism of polyvinyl pyrrolidone and in-situ generated PANI for modifying the dynamic reaction interface. We further clarify the H+ concentration and the surfactant types serve as main descriptors to tune the reaction dynamics. Besides, by applying other aniline oligomers, a series of similar eccentric structures can also be obtained, indicative of the good applicability of our strategy. Such a sub-micron eccentric structure furnishes the Ag@PANI composites with sound performance for microwave absorption, as demonstrated by a minimum reflection loss (RL) value of −35 dB with an effective absorption bandwidth of 3.7 GHz. This study provides an inspiring scope/concept of eccentric microstructure engineering for better meeting the demands in the high-tech military, energy, environment fields, and beyond.
As one of the 2D transition metal sulfides, 1T phase MoS2 nanosheets (NSs) have been studied because of their distinguished conductivity and suitable electronic structure. Nevertheless, the active sites are limited to a small number of edge sites only, while the basal plane is catalytically inert. Herein, we report that boron (B) doped 1T phase MoS2 NSs can replace precious metals as a co-catalyst to assist in photocatalytic H2 production of 2D layered g-C3N4 nanosheets (g-C3N4 NSs). The H2 evolution rate of prepared B-MoS2@g-C3N4 composites with 15 wt% B-MoS2 (B-MoS2@g-C3N4–15, 1612.75 µmol h−1 g−1) is 52.33 times of pure g-C3N4 NSs (30.82 µmol h−1 g−1). Furthermore, the apparent quantum efficiency (AQE) of B-MoS2@g-C3N4–15 composites under the light at λ = 370 nm is calculated and reaches 5.54%. The excellent photocatalytic performance of B-MoS2@g-C3N4–15 composites is attributed to the B ions doping inducing the distortion of 1T phase MoS2 crystal, which can activate more base planes to offer more active sites for H2 evolution reaction (HER). This work of B-MoS2@g-C3N4 composites offers experience in the progress of effective and low-price photocatalysts for HER.
Inosine is a vital RNA modification across three kingdoms of life. It has been demonstrated that inosine plays important roles in modulation of the fate of RNAs. In the current study, we developed a highly sensitive method to determine inosine in a single cell by N-cyclohexyl-N'-β-(4-methylmorpholinium)ethylcarbodiimide p-toluenesulfonate (CMCT) derivatization in combination with mass spectrometry analysis. The results showed that the detection sensitivity of inosine was increased by 556-fold after CMCT derivatization, with the limit of detection (LOD) being 4.5 amol. With the established method, we could detect inosine from 13.0 pg of total RNA of HEK293T cells. Meanwhile, inosine in RNA from a single cell could also be clearly detected due to the improved detection sensitivity. Moreover, we found the level of inosine in RNA of sleep-deprived mice was significantly increased compared to the control mice, indicating that inosine is associated with sleep behavior and might be a potential indicator of sleep disorder. Taken together, the chemical derivatization coupled with mass spectrometry analysis offers a valuable tool in determination of endogenous RNA modifications in a single cell, which should benefit the functional study of RNA modification in rare clinical samples.
The effective removal and selective detection of explosive and toxic pollutant trinitrophenol (TNP) is an attractive but challenging field. Herein, a double-cavity nor-seco-cucurbit[10]uril (ns-Q[10])-based supramolecular assembly 8-HQ@ns-Q[10] was fabricated and its structure was characterized by X-ray single crystal diffraction. In this assembly, the stoichiometric ratio of ns-Q[10] and 8-hydroxyquinoline (8-HQ) is 1:2, which is also attributed to the special double-cavity structure of ns-Q[10]. The luminescence sensing experiments showed that 8-HQ@ns-Q[10] can be used as a good fluorescence-enhanced sensing material (enhanced 27-fold) for the rapid detection of explosives and the aqueous contaminant TNP, with a limit of detection (LOD) of 2.07 × 10−5 mol/L, without interference from other phenolic compounds. Furthermore, TNP can be efficiently removed in the presence of assembly 8-HQ@ns-Q[10], and the removal efficiency is more than 89%. Therefore, the supramolecular assembly 8-HQ@ns-Q[10], as a fluorescence-enhanced luminescence sensor and adsorption material, has rich research value and potential application prospect when applied to the detection and removal of TNP in aqueous environment.
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