Latest ArticlesAn Ir8Pd4-heteronuclear metal-organic cage (MOC-51) was assembled from bipodal metalloligand[Ir(ppy)2(qpy)(BF4)] (qpy=4, 4':2', 2":4", 4"'-quaterpyridine; ppy=2-phenylpridine) with Pd(Ⅱ) salt. The cubic barrel shaped MOC shows one-photon and two-photon excited deep-red emission, as well as large singlet oxygen quantum yields under visible light irradiation, therefore exhibiting great potentials in organelles-targeted cell imaging and photodynamic therapy (PDT). Compared with the Ir(Ⅲ) metalloligand, the Ir8Pd4-MOC showed less dark toxicity and higher mitochondria-targeting efficiency. The localization in mitochondria overcomes the limitation of short lifetime and diffusion distance of ROS in cell, thus improved PDT effect can be obtained in low light dose usage of the MOC. This study presents the first case of Ir-based metal-organic cages for bio-applications in successful integration of imaging diagnosis and photodynamic therapy
An ultrasensitive detection and effective removal material was successfully developed by using a pillar[n] arene-based supramolecular polymer gel (MTP5⊃HB). The MTP5⊃HB can ultrasensitively recognize Cu2+ and Fe3+, and the limits of detection (LODs) for Cu2+ and Fe3+ are 1.55 and 2.68 nmol/L, respectively. Additionally, the in-situ generated metallogel MTP5⊃HB-Cu can exclusively detect CN-, and the LOD for CN- is 1.13 nmol/L. Noticeably, the xerogel of MTP5⊃HB-Cu can effectively remove CN- from aqueous solution with 94.40% removal rate. Test kit based on MTP5⊃HB-Cu is also prepared for convenient detection of CN-.
Drug delivery systems (DDSs) are of paramount importance to deliver drugs at the intended targets, e.g., tumor cells or tissue by prolonging blood circulation and optimizing the pharmaceutical profiles. However, the therapeutic efficacy of DDSs is severely impaired by insufficient or non-specific drug release. Dynamic chemical bonds having stimuli-liable properties are therefore introduced into DDSs for regulating the drug release kinetics. This review summarizes the recent advances of dynamic covalent chemistry in the DDSs for improving cancer therapy. The review discusses the constitutions of the major classes of dynamic covalent bonds, and the respective applications in the tumor-targeted DDSs which are based on the different responsive mechanisms, including acid-activatable and reduction-activatable. Furthermore, the review also discusses combination strategies of dual dynamic covalent bonds which can response to the complex tumor microenvironment much more accurately, and then summarizes and analyzes the prospects for the application of dynamic covalent chemistry in DDSs.
HYL derived from the venom of the solitary bee Hylaeus signatus (Hymenoptera:Colletidae) is an α-helical antimicrobial peptide with 16 residues. To explore whether HYL can be applied in anti-tumor therapy, we synthesized HYL and further modified its structure by using a solid-phase synthesis method, and then evaluated their antitumor activities. Firstly, we identified the key residues of HYL by alanine scanning strategy, and then a series of stapled peptides were synthesized by hydrocarbon stapling strategy without destroying the key residues. All the stapled peptides of HYL showed significant improvement not only in α-helicity, but also in antitumor activity and protease resistance when compared to the parent peptide HYL. The results showed that hydrophobicity and amphiphilicity are important factors affecting the antitumor activity of HYL, and the stapling strategy can significantly affect the proteolytic stability and helicity of HYL. What's more, we find that the stapled peptides HYL-14, HYL-16 and HYL-18 show a promising prospect for novel anti-tumor drug development.
The widely accepted theory concerning the electrochemical energy storage mechanism of copper hexacyanoferrate (CuHCF) for supercapacitors is that CuHCF stores charge by the reversible redox processes of Fe3+/Fe2+ couple and Cu cations are electrochemically inactive. In this work, CuHCF nanocubes (CuHCF-NC) were synthesized in the presence of potassium citrate and its electrochemical properties were tentatively studied in 1 mol/L Na2SO4 aqueous electrolyte. Good supercapacitive performance was exhibited. The combined analyses of cyclic voltammogram (CV) and X-ray photoelectron spectroscopy (XPS) disclosed that the CuHCF nanocubes underwent the redox reactions of Fe3+/Fe2+ and Cu2+/Cu+ couples to store charges. The Cu2+/Cu+ redox couple was activated due to the strong coordination interaction between the carboxylate groups of citrate ions and surface Cu cations.
A supramolecular dimer of doxorubicin (DOX) was constructed via ternary host-guest interactions between cucurbit[8]uril (CB[8]) and tryptophan modified DOX (DOX-Trp, connected with an acid-labile bond) and we demonstrate for the first time that a supramolecular dimer of DOX can be formed upon homo-dimerization by CB[8], which may act as a stimuli pH-responsive, supramolecular DOX dimer prodrug system. This supramolecular DOX dimer transported DOX efficiently and selectively to cancer cells, thereby exhibiting significantly minimized cytotoxicity against noncancerous cells while maintaining effective cytotoxicity against cancer cells. Under this strategy, many other anticancer drugs could be chemically modified and loaded as a dimeric "ammunition" into CB[8] as supramolecular dimer prodrug systems (or a "jet fighter") for improved cancer therapy.
For organnoboron compounds, the substituents on boron atoms are very important because they not only impact on the molecular stability but also significantly modulate the electronic structures and properties. In this manuscript, we synthesized two new B←N-containing azaacenes with propynyl groups on boron atoms through one-step Grignard reaction. Replacing fluorine atoms by propynyl groups greatly impacts on the electronic energy levels, especially enhancing the HOMO levels, thus leading to the narrowed HOMO-LUMO bandgaps. These B←N-containing azaacenes exhibit the NIR light-absorption (λabs=706 nm for 2a and 762 nm for 2b) and fluorescence properties (λem=740 nm for 2a and 802 nm for 2b), as well as multiple reversible redox behaviors, which are significantly different from the analogs with fluorine atoms. This study thus provides a functional substituent of boron atom, which may lead to new organoboron materials with fascinating properties.
Because of their high capacity and low potential, lithium metal anodes are considered to be promising candidates for next generation electrode materials. However, the safety concerns and limited cycling life associated with uncontrollable dendrite growth hamper practical applications. In this work, the acidified cellulose ester, which is a mixed fiber microporous membrane film, was used as a novel electrolyte additive that effectively improves the cycle stability of the lithium metal anode and inhibits dendrite growth. The focus of this paper is on inhibiting the formation and growth of lithium dendrites. The coulombic efficiency of a Li|Cu battery with this acidified cellulose ester additive remains stable at 99% after 500 cycles under a current density of 1 mA/cm2. Symmetric batteries also remain stable after 500 cycles (1000 h) under a current density of 1 mA/cm2. These superior properties can be ascribed to the induced nucleation and the uniform distribution of lithium ion flux. This study uncovers an approach for effectively enabling stable cycling of dendrite-free lithium metal anodes.
The effective valuation of catalyst supports in the catalytic oxidation makes the contribution to understand the support effect of great interest. Here, the role of active substrate in the performance and stability of Cu-Fe-Co ternary oxides was studied towards the complete catalytic oxidation of CO. The Cu-Fe-Co oxide thin films were deposited on copper grid mesh (CUGM)using one-step pulsed-spray evaporation chemical vapor deposition method. Crystalline structure and morphology analyses revealed nano-crystallite sizes and dome-top-like morphology. Synergistic effects between Cu, Fe and Co, which affect the surface Cu2+, Fe3+, Co3+ and chemisorbed oxygen species (O2- and OH-) of thin films over the active support and thus result in better reducibility. The thin film catalysts supported on CUGM exhibited attractive catalytic activity compared to the ternary oxides supported on inert grid mesh at a high gas hourly space velocity. Moreover, the stability in time-on-stream of the ternary oxides on CUGM was evaluated in the CO oxidation for 30 h. The adopted deposition strategy of ternary oxides on CUGM presents an excessive amount of adsorbed active oxygen species that play an important role in the complete CO oxidation. The catalysts supported on CUGM showed better catalytic conversion than that on inert grid mesh and some literature-reported noble metal oxides as well as transition metal oxides counterparts, revealing the beneficial effect of the CUGM support in the improvement of the catalytic performance.
Highly active N, O-doped hierarchical porous carbons (NOCs) are fabricated through the in-situ polymerization and pyrolysis of o-tolidine and p-benzoquinone. As-prepared NOCs have a variety of faradaic-active species (N-6, N-5 and O-I), high ion-accessible platform (1799 m2 /g) and hierarchically micro-meso-macro porous architecture. Consequently, the resultant NOC electrode delivers an advantageous specific capacitance (311 F/g), with a pseudocapacitive contribution of 37% in a threeelectrode configuration, and an enhanced energy output of 18.0 Wh/kg@350 W/kg owing to the enlarged faradaic effect in an aqueous redox-active cell. Besides, a competitive energy density (74.9 Wh/kg) and high-potential durability (87.8%) are achieved in an ionic liquid (EMIMBF4)-assembled device. This study sheds light on a straightforward avenue to optimize the faradaic activity and nanoarchitecture for advanced supercapacitors.
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