Latest ArticlesAchieving efficient adsorption and separation of C2H2/CO2 mixtures is a goal that people have always pursued to improve the situation of high energy consumption brought by traditional separation technologies in industry today. High-nuclearity metal cluster-based MOFs with different functionalities are promising for this separation, but it is a complicated and difficult task to precisely control their structures. The strategy of pore-space partition (PSP) is a powerful way to construct this type MOFs, which has the characteristic of isostructural relationship, and can be resulted in a similar performance for them. Therefore, it is an interesting work to explore the effect of MOFs property by adjusting the size of PSP dividers. Herein, three tetranuclear Cu(Ⅱ) cluster-based MOFs (FJU-112/113/114) with dual functionalities has been successfully obtained by PSP strategy with various lengths of divider units. With the highest microporosity and unique functional site, FJU-114 realized a good improvement in the adsorption and separation performance of C2H2/CO2. The gas adsorption and lab-scale C2H2/CO2 breakthrough experiments demonstrated that FJU-114 exhibits the highest adsorption uptake of 77 cm3/g for C2H2, and shows the best separation factor of 4.2 among three MOFs. The GCMC simulation reveals that a stronger adsorption binding site of C2H2 in FJU-114a located in the cage Ⅱ near the unchanged tetranuclear copper node, combined with its high microporosity to achieve the effect of dual functionalities for the improvement performance of C2H2 adsorption and separation.
Hymoins A–C (1–3), three unusual polycyclic polyprenylated acylphloroglucinols (PPAPs) were isolated from the flowers of Hypericum monogynum. Hymoin A features the first intriguing 6/5/5/5/7 pentacyclic caged PPAP. Hymoin B is characterized by an unprecedented rearranged 5/6/8 tricyclic ring system, while hymoin C represents the first rearranged PPAP with a fantastic spirocyclic 5/6/7 ring system. Their structures were established by extensive spectroscopic analysis, X-ray crystallography, and computational methods. The plausible biosynthetic routes for the compounds were also proposed. In oleic acid (OA)-induced HepG2 cells, all compounds exhibited significant lipid-lowering activity at the concentrations of 2–8 µmol/L. Further mechanistic study implied that compound 1 exhibited excellent lipid-lowering activity in OA-induced HepG2 cells through inhibiting the proteins of free fatty acids synthesis and improving lipidolysis.
Density functional theory (DFT) was performed to systematically study the adsorption and dissociation of N2 on Ir(100) and Ir(110) surfaces. By analyzing the properties, including adsorption energies, reaction barriers, and optimal adsorption sites, the hollow (H) sites were finally identified as favorable dissociation sites for N2. The dissociation barriers of N2 are 0.87 eV on Ir(100) and 1.12 eV on Ir(110), which can be overcome at around 348 and 448 K, respectively. Therefore, Ir(100) is screened as a promising catalyst for N2 dissociation compared to Ir(110). This can be attributed to the significantly higher adsorption energy of N2 on the H site of Ir(100) (−0.48 eV) compared to that on Ir(110) (−0.22 eV), leading to different dissociation mechanisms on Ir(100) and Ir(110). Ir(100) can dissociate N2 directly on H site and Ir(110) should firstly capture N2 via bridge site and further transfer the adsorbed N2 to the H site, which will dramatically deteriorate the reactivity of N2 dissociation. In addition, the following protonation processes of dissociated *N atoms are all exothermal at 348 K on Ir(100), indicating that the ammonia synthesis can occur spontaneously as the temperature higher than 348 K. These results have provided a reasonable materials design scheme for subsequent ammonia synthesis.
The cyclic guanosine monophosphate-adenosine monophosphate synthase and the stimulator of interferon genes (cGAS-STING) has emerged as a promising target for cancer immunotherapy. However, the development of natural STING agonists is impeded by several challenges, including limited biostability, poor pharmacokinetics, and inefficient cytosolic delivery. Herein, we meticulously designed a double-layer polyethylenimine (PEI) modified nanoscale covalent organic polymer (CPGP) for efficient delivery of 2′3′ cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), a natural STING agonist. The double-layer PEI structured CPGP enhanced both the loading capacity and stability of cGAMP. Furthermore, CPGP improved the intracellular delivery efficiency and amplified the activation of STING pathway for the secretion of type-Ⅰ interferon and pro-inflammatory cytokines. In contrast, single-layered nanoparticles failed to permit stable loading and intracellular delivery of cGAMP for immune response. The nano-STING agonist also mitigated the immunosuppressive tumor microenvironment (TME) by reducing regulatory T cells and polarizing M2 macrophages to the M1 phenotype, thereby creating an immune-supportive TME to enhance adaptive immune responses. The combination of CPGP and immune checkpoint blockers showed synergistic effect, further enhancing the inhibition effect on tumor growth. This double-layer PEI modified CPGP may offer a generalizable platform for other natural dinucleotide STING agonists to overcome the cascade delivery barriers, augmenting immune activation for tumor immunotherapy.
Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A (1). Its structure was determined by spectroscopic analysis, computational electronic circular dichroism (ECD)/optical rotatory dispersion (ORD) methods, and X-ray crystallography. Compound 1 represents a new skeleton with an uncommon 6/6/6/5/6/5/6/5 octacyclic system, which is presumably biosynthesized via a [4 + 2] cycloaddition and an enzymatic cyclization. Chaeglobol A (1) exhibited inhibitory activity against B. dothidea by destroying cell membrane integrity and causing oxidative damage within the cells.
Biocompatible amphiphilic nanoparticles (NPs) with tunable particle morphology and surface property are important for their applications as functional materials. However, previously developed methods to prepare amphiphilic NPs generally involve several steps, especially an additional step for surface modification, greatly hindering their largescale production and widespread applications. Here, a versatile one-step strategy is developed to prepare biocompatible amphiphilic dimer NPs with tunable particle morphology and surface property. The amphiphilic dimer NPs, which consist of a hydrophobic shellac bulb and a hydrophilic poly(lactic acid) (PLA) bulb with PLA-poly(ethylene glycol) (PEG) on the bulb surface, are prepared in a single step by controlled co-precipitation and self-assembly. Amphiphilic PLA-PEG/shellac dimer NPs demonstrate excellent tunability in particle morphology, thus showing good performances in controlling the interfacial curvature and emulsion type. In addition, temperature-responsive PLA-poly(N-isopropyl acrylamide) (PNIPAM)/shellac dimer NPs are prepared following the same method and emulsions stabilized by them show temperature-triggered response. The applications of PLA-PEG-folic acid (FA)/shellac dimer NPs for drug delivery have also been demonstrated, which show a very good performance. The strategy of preparing the dimer NPs is green, scalable, facile and versatile, which provides a good platform for the design of dimer NPs with tunable particle morphology and surface property for diverse applications.
Deprivation of glucose and lactate provides an effective pathway to terminate the nutrients supplement for tumor growth. In this work, biomimetic nanozymes called m@BGLC are constructed for catalytic tumor inhibition through nutrients deprivation and oxidative damage induction. Concretely, the catalytic enzymes of glucose oxidase (GOx), lactate oxidase (LOx) and chloroperoxidase (CPO) are precrosslinked with bovine serum albumin (BSA) to construct nanozymes, which are then biomimetic functionalized with cancer cell membrane to prepare m@BGLC. Benefiting from the biomimetic camouflage with homologous cell membrane, m@BGLC inherit homotypic binding and immune escape abilities, facilitating the tumor targeting accumulation and preferable cell internalization for improved drug delivery efficiency. Subsequently, under the cascade catalysis of nanozymes, m@BGLC consume glucose and lactate for tumor starvation therapy through nutrients deprivation, and meanwhile, the resulting hyprochloric acid (HClO) causes an oxidative damage of cells to synergistically inhibit tumor growth. In vitro and in vivo findings demonstrate a robust tumor eradication effect of m@BGLC without obvious adverse reactions via the targeted combination therapy. Such cascade catalytic nanomedicine may inspire the development of sophisticated strategies for tumor combination therapy under unfavorable tumor microenvironments.
Glial fibrillary acidic protein (GFAP) is one of the discriminative biomarkers for diagnosing traumatic brain injury (TBI), and accurate determination of GFAP is clinically significant. In this study, a novel fluorescence immunoassay system was designed. We encapsulated carbon dots with a high fluorescence quantum yield (QY = 92.5%) inside silicon nanocapsules to serve as fluorescent markers. These markers were then integrated with the streptavidin (SA)-biotin biomagnification system and immunomagnetic separation technology for the sensitive detection of GFAP. Based on the signal cascade amplification effect of the silicon nanocapsules and SA-biotin, the fluorescence signal of the SA-biotin-modified immunofluorescence nanocapsules increased 3.6-fold compared to the carbon dot-based immunoprobe. The fluorescence immunoassay system was constructed for GFAP using SA-biotin-modified immunocapsules as the sensing probe and immunomagnetic nanoparticles as the immunorecognition probe. The fluorescence immunoassay system can specifically and ultra-sensitively quantify GFAP in blood samples, with a detection range of 10 pg/mL–10 ng/mL and detection limits of 3.2 pg/mL (serum) and 3.6 pg/mL (plasma). Moreover, the fluorescence immunoassay system exhibited prominent recoveries of 99.4%–100.4% (phosphate buffered saline), 96%–102.6% (serum), and 93.2%–110.2% (plasma), with favorable specificity and excellent stabilization. The novel fluorescence immunoassay system provides a new approach to the clinical analysis of GFAP and may serve as a potential tool for screening and diagnosing TBI.
The utilization of ethane-selective materials for adsorption-based separation technology presents an energy-efficient alternative to cryogenic distillation for ethylene (C2H4) purification from ethane (C2H6). To study the relations between separation performance and pore environments, we carried out the isoreticular chemistry rule to introduce the -NH2 groups into a C2H6-selective MOF [Cu1.5(BTC)(DPU)1.5(H2O)1.5], and successfully improved the adsorption capacity and selectivity for C2H6 over C2H4. The NH2-functionalized MOF [Cu1.5(NH2-BTC)(DPU)1.5(H2O)1.5] with a relatively narrow pore not only forms appropriate pore restriction but also provides additional binding sites to enhance the adsorption capacity of C2H6 relative to C2H4. Both gas adsorption and dynamic breakthrough results indicated that the -NH2 functionalization significantly enhanced the separation performance of materials for C2H6/C2H4 mixtures, allowing the production of C2H4 with a purity of over 99.99% and a productivity of up to 30.02 L/kg in one step. Theoretical calculations revealed that the synergistic effect of appropriate pore confinement and NH2-modified functional surfaces imposed stronger interactions on C2H6 than C2H4.
In the field of Raman spectroscopy detection, the quest for a non–noble metal, recyclable, and highly sensitive detection substrate is of utmost importance. In this work, a new crystalline and noble metal–free substrate of [Bi(DMF)8][PMo12O40] (Bi–PMo12) is designed, which is composed of [PMo12O40]3− and solvated [Bi(DMF)8]3+ cations. Mechanistic studies have revealed that Raman scattering quenching phenomenon arises from two main factors. Firstly, it arises from the absorption of the scattered light due to the transition of a single electron in the reduced state of MoV between 4d orbitals. Secondly, after the interaction between the substrate and hydrazine, the surface undergoes varying degrees of roughening, leading to an impact on the scattered light intensity. These two effects collectively contribute to the detection of low concentrations of N2H4. As a result, Bi–PMo12 opens up a novel Raman scattering quenching mechanism to realize the detection of reduced N2H4 small molecules. A remarkably low detection limit of 4.5 × 10−9 ppm for N2H4 is achieved on the Bi–PMo12 substrate. This detection has a lower concentration than the currently known SERS detection of N2H4. Moreover, Bi–PMo12 can be recovered and reused through recrystallization, achieving a recovery rate of up to ca. 51%. This study reveals the underlying potential of crystalline polyoxometalate materials in the field of Raman detection, thus opening up new avenues for highly sensitive analysis using Raman techniques.
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