Latest ArticlesDynamic manipulation of enzymatic activity is a challenging task for applications in chemical and pharmaceutical industries due to the difficult modification and variable conformation of various enzymes. Here, we report a new strategy for reversible dynamic modulation of enzymatic activity by near-infrared light-induced photothermal conversion based on polyphenol-functionalized liquid metal nanodroplets (LM). The metal-phenolic nanocoating not only provides colloidal stability of LM nanodroplets but also generates nanointerfaces for the assembly of various enzymes on the LM nanodroplets. Upon near infrared (NIR) irradiation, the localized microenvironmental heating through photothermal effect of the LM nanodroplets allows tailoring the enzymatic activity without affecting the bulk temperature. A library of functional enzymes, including proteinase K, glucoamylase, glucose oxidase, and Bst DNA polymerase, is integrated to perform a reversible control and enhanced activities even after five times of cycles, demonstrating great potential in bacterial fermentation, bacteriostasis, and target gene amplification.
Macrocycle-based glycoclusters, on account of their promising anti-adhesive properties against bacteria, are potential therapeutic alternatives to classic antibiotics through the much less explored anti-adhesive strategy. In this study, a series of constitutionally-pure pentavalent glycoclusters was prepared by conjugating assorted azido-carbohydrates onto a penta-propargyl rim-differentiated pillar[5]arene (RD-P[5]) scaffold through Cu(I)-catalyzed azide–alkyne cycloaddition "click" reactions. Their binding towards therapeutically relevant bacterial lectins, such as LecA and LecB from Pseudomonas aeruginosa and concanavalin A (ConA), were evaluated subsequently by isothermal titration calorimetric studies. Most of these isomer-free RD-P[5] pentavalent glycoclusters, except the fucosylated ones, display good affinities to lectins. Nonetheless, the dissociation constants observed are similar to those displayed by an analogous pentavalent glycocluster consisting of four P[5] constitutional isomers, in which the RD-P[5] component merely accounts for 7% in the mixture. Our results revealed that high constitutional purity is not essential for achieving effective multivalent interactions between P[5]-based glycoclusters and lectins, presumably as a result of the conformationally labile nature of the P[5] scaffold. This information provides valuable design principles for low-cost and facile syntheses of glycosylated P[5]s for biomedical applications.
The issue about how outstanding scientists obtained innovative findings has drawn the interest of researchers in science, policy and scientometrics. Here, we attempt to address this question by using computational methods to measure the cognitive content and concepts of K. Barry Sharpless' research and estimate the knowledge flow of his click chemistry to other fields. First, we traced Sharpless' conceptual journey over time through topic modeling approach, mapping and clustering of the epistemic network from distant reading his publications. We find that connectivity and functions, the core features of click chemistry, are embodied in his constant search for simplicity. What makes simplicity possible is his continuous work with collaborators on reactivity and reaction mechanisms. Moreover, citation and link analysis show that click chemistry had a much richer impact on other research fields than what is generally acknowledged, and drew solutions to significant and practical questions back to chemistry from biology. Together with these findings, we propose that the click chemistry philosophy follows the way that values nature's principle. Chemistry has a clear-cut epistemic domain in modeling Nature. Thus, click chemistry as a concept on doing science beyond a connective technology goes across the boundaries between disciplines and impacts many other fields.
The rapid prevalence of antibiotic resistance has led to a significant global health problem. Although colistin is the last resort antibiotic, it is limited by dose dependent toxicity. A critical approach to solve this problem is to use an antibiotic adjuvant, which is able to potentiate the activity of antibiotic and reduce the dosage of antibiotic. Herein, we reported a novel 2-aminothiazoyl piperidine adjuvant, which enhanced the activity of colistin against Acinetobacter baumannii (A. baumannii). Two pilot libraries of 40 compounds were prepared and their adjuvant activities were evaluated. The most potential compound 11j enabled to cause16-fold reduction in the minimum inhibitory concentration (MIC) of colistin at 8 µg/mL. Besides, time-kill curves exhibited that compound 11j had significant adjuvant activity to kill the bacteria. The predicted ADMET analysis showed that 2-aminothiazoyl piperidine derivatives had good drug-likeness and acceptable physicochemical properties. Furthermore, membrane permeability experiments demonstrated that compound 11j was beneficial for colistin to destroy the outer membrane of bacteria. Also, the comparative molecular similarity indices analysis (CoMSIA) and the density functional theory (DFT) calculations were conducted. The results drawn from these analyses indicated that the novel scaffold provided helpful information for the finding of new adjuvant lead.
Lithium dendrite growth due to uneven electrodeposition usually leads to the potential hazard of internal short circuit and shorter lifetime of lithium-based batteries. Extensive efforts have been devoted to explore the effects of single or two factors on dendrite growth, involving the diffusion coefficient, exchange current density, electrolyte concentration, temperature, and applied voltage. However, these factors interrelate during battery operation, signifying that a understanding of how they jointly influence the electrodeposition is of paramount importance for the effective suppression of dendrites. Here, we incorporate the dependent relationships among key factors into the phase-field model to capture their synergistic effects on electrodeposition. All the simulations are implemented in our self-written MATLAB code under a unified modeling framework. Following this, five groups of experimentally common dendrite patterns are reproduced and the corresponding electrodeposition driving forces are identified. Unexpectedly, we find that with the decrease of the ratio of exchange current density (or applied voltage) to diffusion coefficient, the electrodeposition morphology changes from needle-like dendrites to columnar dendrites and to uniform deposition. The present phase-field simulation tends to depict the practical electrodeposition process, providing important insights into synergistic regulation to suppress dendrite growth.
Lanthanide metal-organic frameworks (Ln-MOFs), which is composed of organic bridging ligands and Ln3+ ions/clusters, is an important component of luminescent MOFs. Compared with transition metal ions, lanthanide ions have a higher coordination number and abundant coordination geometry. Moreover, Ln-MOFs have special characteristics such as good porosity, topological diversity, high surface area and highly adjustable structure. The energy transfer (ET) process in Ln-MOFs could be easily affected by the interaction between host framework and guest, resulting in the change of luminescence intensity or color. Over the past few decades, the features of Ln-MOFs open the door to a range of incredibly important applications. However, there are few reviews on systemic summary of the various applications of Ln-MOFs. In this paper, we summarized the latest progress of Ln-MOFs applications, including the Ln-MOFs in chemical and biological sensors, optical information devices and catalysis, respectively, and discussed design mechanism. The possible problems in current research are briefly prospected, hoping to provide some helpful guidance for the future development of Ln-MOF materials.
2D MBenes have been theoretically predicted to possess unique electronic structures and physicochemical properties, and thus shown great promise in various applications. However, the synthesis of individual single-layer MBene remains a grand challenge due to its orthorhombic structure of MAB phases. Recently, scientists from Linköping University have fabricated 2D monolayer Mo4/3B2-xTz with ordered metal vacancies. Their results demonstrated the feasibility of top-down approach by chemical exfoliation of laminated compounds and provided the principle for further preparation of a wealth of MBenes.
Chemical fixation of CO2 into C1 source, as a general approach, can effectively alleviate the emission of greenhouse gasses. Whereas, the challenge posed by the need for efficient catalysts with high catalytic active sites still exists. In this work, we reported a series of new hexavanadate clusters, [(C6H6ON)2(C2H8N2)2(CH3O)6V6IVO8] (V6–1), [(C6H6ON)2(C3H10N2)2(CH3O)6V6IVO8] (V6–2), [(C6H6ON)2(C6H14N2)2(CH3O)6V6IVO8] (V6–3) and [(C6H6ON)2(C4H11N2O)2(CH3O)4V6IVO8] (V6–4), assembled by 2-aminophenol and four different kinds of Lewis bases (LB), ethanediamine (en), 1,2-diaminopropane, 1,2-cyclohexanediamine and N-(2-hydroxyethyl)ethylenediamine (ben) together. Among them, the basic unit {V6} cluster featured Z-shaped configuration represents a brand-new example of hexanuclear vanadium clusters. Remarkably, the catalytic tests demonstrated that V6–1 as catalyst displays high catalytic activity in the cycloaddition for the CO2 fixation into cyclic carbonates by virtue of open V sites. As expected, for oxidative desulfurization of sulfides, V6–1 also exhibits satisfied catalytic effectiveness. Furthermore, the recycling test confirmed that catalyst V6–1 may be a bifunctional heterogeneous catalyst with great promise for both CO2 cycloaddition and oxidative desulfurization reactions.
Supramolecular chemistry has received considerable attention in host-guest recognition. The structure-response relationship of host-guest recognition system is a meaningful issue. Herein, a series of tripodal nitrogen mustard derivatives (TMs) have been developed in this paper. By rationally design the intramolecular alkyl chain lengths of host, the host-guest binding model have been successfully tuned, which underwent a transformation from π-π to multiple hydrogen bonds. This process enhances the host-guest binding force and recognition efficiency.
Separator is supposed to own outstanding thermal stability, superior wettability and electrolyte uptake, which is essential for developing high-rate and safe lithium metal batteries (LMBs). However, commercial polyolefin separators possess poor wettability and limited electrolyte uptake. For addressing this issue, we put forward a composite separator to implement above functions by doping layered-silicate (talcum) into polyvinylidene fluoride (PVDF). With significant improvement of electrolyte absorption benefiting from the strong adsorption energy values (-1.64 ~ -1.70 eV) between talcum and the electrolyte in lithium metal batteries, PVDF/Talcum (PVDF/TM) composite separator owns a small contact angle and superior electrolyte uptake. PVDF/TM composite separator with 10 wt% talcum (T-10) owns a tiny contact angle of 8°, while those of polypropylene (PP) and PVDF are 48° and 20° with commercial electrolyte. Moreover, the addition of thermotolerant talcum endows the T-10 composite separator with great thermostability, whose thermal shrinkage is only 5.39% at 150 ℃ for 0.5 h. The cell with LiFeO4 cathode and the T-10 composite separator reaches 91.7 mAh/g in discharge capacity at 4.8 mA/cm2 (10 C), far superior to that with pure PVDF separator (56.3 mAh/g) and PP (51.4 mAh/g).
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