Synthesis of Pillar[5]arene- and Phosphazene-Linked Porous Organic Polymers for Highly Efficient Adsorption of Uranium.

It is crucial to design efficient adsorbents for uranium from natural seawater with wide adaptability, effectiveness, and environmental safety. Porous organic polymers (POPs) provide superb tunable porosity and stability among developed porous materials. In this work, two new POPs, i.e., HCCP-P5-1 and HCCP-P5-2 were rationally designed and constructed by linked with macrocyclic pillar[5]arene as the monomer and hexachlorophosphate as the core via a macrocycle-to-framework strategy. Both pillar[5]arene-containing POPs exhibited high uranium adsorption capacity compared with previously reported macrocycle-free counterparts. The isothermal adsorption curves and kinetic studies showed that the adsorption of POPs on uranium was consistent with the Langmuir model and the pseudo-second-order kinetic model. Especially, HCCP-P5-1 has reached 537.81 mg/g, which is greater than most POPs that have been reported. Meanwhile, the comparison between both HCCP-P5-1 and HCCP-P5-2 can illustrate that the adsorption capacity and stability could be adjusted by the monomer ratio. This work provides a new idea for the design and construction of uranium adsorbents from macrocycle-derived POPs.

α-Active Pyrylium Salt 2,4,5-Triphenylpyrylium for Improved Mass Spectrometry-Based Detection of Peptides.

Pyrylium salts are considered efficient chemical tags for amino groups. However, the apparent steric selectivity of pyrylium salts limits their application in the field of chemical labeling, especially during the labeling of sterically hindered compounds like amino acids, peptides, and proteins. Herein, we have investigated the effects of the α-substitution of pyrylium salts on their reactivity. We have also investigated the mechanism of nucleophilic reactions with pyrylium salts and further proposed that the reactivity of pyrylium salts mainly depends on the position and type of their substituents. A series of pyrylium salts were synthesized, and a highly active α-monosubstituted pyrylium salt, 2,4,5-triphenylpyrylium, was developed for efficient chemical labeling. All of the 15 amino acids studied were efficiently labeled under optimized reaction conditions. The 2,4,5-triphenylpyrylium salt was highly efficient in comparison to the previously reported 2,4,6-triphenylpyrylium salt developed for lysine-specific modifications. Furthermore, we successfully used 2,4,5-triphenylpyrylium salt for the hydrophobic labeling of peptides and protein hydrolysates. The most striking observation was that the ionization efficiency of short-chain multilabeled peptides in mixed samples, after derivatization, increased by up to 60 times. The increase in ionization efficiency gradually decreased with increasing peptide chain length. During the "soft" collision-induced dissociation (CID) process, the peptide was tagged at the N-terminus with 2,4,5-triphenylpyrylium, producing abundant a-type ions and b-type ions (Δ = 28), which eases the peptide resequencing process and assists in cracking the peptide codes. Moreover, 2,4,5-triphenylpyrylium has been utilized for the proteomic analysis of HeLa cell digests. In addition, 215 additional proteins were identified in the labeled products and the coverage of most proteins was improved.

Aggregation-Induced Emission (AIE) Fluorophore Exhibits a Highly Ratiometric Fluorescent Response to Zn2+ in vitro and in Human Liver Cancer Cells.

Two novel organic fluorophores, containing bis-naphthylamide and quinoline motifs, have been designed and synthesized. One of the fluorophores contains an isobutylene unit and exhibits a significant aggregation-induced emission (AIE) and a remarkable highly selective ratiometric fluorescence response towards Zn2+ in solution as well as in human liver cancer cells. The AIE behavior of this fluorophore was fully verified by fluorescence and UV/Vis spectroscopy, quantum yield calculations, and single-crystal X-ray diffraction, which revealed an intricate crystal packing system. Conversely, a fluorophore that lacks the isobutylene moiety did not exhibit any significant fluorescent properties as a result of its more flexible molecular structure that presumably allows free intramolecular rotational processes to occur.

Supramolecular gel from self-assembly of a C3-symmetrical discotic molecular bearing pillar[5]arene.

A novel C3-symmetric benzene-1,3,5-tricarboxamide (BTAs) decorated with three identical pillar[5]arene tails was designed, synthesized and characterized. The compound can gelate acetonitrile at low concentration (0.2 wt%) upon sonication at room temperature, but a precipitate was obtained by a conventional heating-cooling process. Scanning electron microscopy revealed that the gel and precipitate were constructed by entangled, high-aspect-ratio flexible bundles of nanofibrils. UV-vis spectroscopy, circular dichroism, Fourier transform infrared microscopy and powder X-ray diffraction showed that the compound formed chiral, elongated, columnar aggregates with nanofiber morphology by a combination of intermolecular hydrogen bonding between the N-H and C[double bond, length as m-dash]O of amides, π-π stacking (H-aggregates) and hydrophobic interactions of peripheral groups.

Fluorescent Cross-Linked Supramolecular Polymer Constructed by Orthogonal Self-Assembly of Metal-Ligand Coordination and Host-Guest Interaction.

A new host molecule consists of four terpyridine groups as the binding sites with zinc(II) ion and a copillar[5]arene incorporated in the center as a spacer to interact with guest molecule was designed and synthesized. Due to the 120 ° angle of the rigid aromatic segment, a cross-linked dimeric hexagonal supramolecular polymer was therefore generated as the result of the orthogonal self-assembly of metal-ligand coordination and host-guest interaction. UV/Vis spectroscopy, (1) H NMR spectroscopy, viscosity and dynamic light-scattering techniques were employed to characterize and understand the cross-linking process with the introduction of zinc(II) ion and guest molecule. More importantly, well-defined morphology of the self-assembled supramolecular structure can be tuned by altering the adding sequence of the two components, that is, the zinc(II) ion and the guest molecule. In addition, introduction of a competitive ligand suggested the dynamic nature of the supramolecular structure.

Fluorescent cross-linked supramolecular polymers constructed from a novel self-complementary AABB-type heteromultitopic monomer.

A novel AABB-type heteromultitopic monomer (), having a self-complementary perpendicular structure, could solely self-assemble to fluorescent cross-linked supramolecular polymers. Interestingly, the supramolecular gel film shows a sensitive fluorescence change on exposure to acid and base vapor, endowing this system with a potential application in gas detection.

A novel smart supramolecular organic gelator exhibiting dual-channel responsive sensing behaviours towards fluoride ion via gel-gel states.

A novel smart supramolecular organic gelator G-16 containing anion and metal-coordination ability has been designed and synthesized. It shows excellent and robust gelation capability as a strong blue fluorescent supramolecular organic gel OG in DMF. Addition of Zn(2+) produced Zn(2+)-coordinated supramolecular metallogel OG-Zn. Organic gel OG and organometallic gel OG-Zn exhibited efficient and different sensing behaviors towards fluoride ion due to the variation in self-assembling nature. Supramolecular metallogel OG-Zn displayed specific selectivity for fluoride ion and formed OG-Zn-F with dramatic color change from blue to blue green in solution and gel to gel states. Furthermore after directly addition of fluoride into OG produced fluoride containing organic gel OG-F with drastically modulation in color from blue to greenish yellow fluorescence via strong aggregation-induced emission (AIE) property. A number of experiments were conducted such as FTIR, (1)H NMR, and UV/Vis spectroscopies, XRD, SEM and rheology. These results revealed that the driving forces involved in self-assembly of OG, OG-Zn, OG-Zn-F and OG-F were hydrogen bonding, metal coordination, π-π interactions, and van der Waal forces. In contrast to the most anion responsive gels, particularly fluoride ion responsive gels showed gel-sol state transition on stimulation by anions, the gel state of OG and OG-Zn did not show any gel-to-sol transition during the whole F(-) response process.

Two bent-shaped π-organogelators: synthesis, fluorescence, self-assembly and detection of volatile acid vapours in gel films and in gel-gel states.

Two novel bent-shaped π-organogelators 6a and 6b having different terminal pyridine rings as responsive sites were designed, synthesized and fully characterized. A subtle difference in the position of the N atom at the pyridine ring greatly affected their fluorescence and gelation properties. 6b showed remarkably stronger fluorescence both in solution and in the solid state as compared to 6a. Theoretical calculation revealed a clear discrepancy in the electron distribution between them. Furthermore, driven by π­π stacking interaction and hydrophobic interaction, both 6a and 6b can gelate several organic solvents with different polarities. Rheological studies, spectroscopic tests and powder X-ray diffraction showed that 6a displayed a closer stacking mode leading to stronger gel robustness. The xerogel films of 6a and 6b were prepared and utilized to detect acid vapours. Both of them can fulfil the detection of acid vapours through a distinct fluorescence change which could be seen by the naked eye under a UV lamp, but with different sensing modes. A rare gel to gel transformation was also observed upon exposure to acid vapours accompanied by a morphological change.

Preassembly-driven ratiometric sensing of H2PO4(-) anions in organic and aqueous environments.

Gemini surfactant-like receptor is designed and synthesized. The special preassembly phenomenon of in a nonpolar solvent facilitates the novel ratiometric fluorescence sensing of H2PO4(-)via an anion-induced reassembly process in organic solvents and an anion-induced disassembly process in water.

[New Bipyridinium Salt: Synthesis and Application as a Fluorescence Enhancement Probe of Nitrate Ion].

Anions are ubiquitously distributed not only in biological systems but also in environment. Accordingly, anion recognition and sensing have attracted increasing attention due to the important roles anion plays in biological, chemical and environmental fields. Among various anionic species, NO3- is a very important inorganic anions which has a great harm to the environment and human health. At present, methods for the determination of NO3- mainly contained electrochemical method, ion chromatography and ion selective electrode method. Although all methods have their own advantages, but also has the obvious deficiency. Such as, the reproducibility of electrochemical method is not good, and ion chromatography and ion selective electrode method usually require expensive apparatus and lengthy analytical time. As a contrast, fluorescence spectroscopy become a hot research topic in anion recognition and detection because of its high sensitivity and easy operation and other advantages in recent years. New bipyridinium salt L was designed and synthesized using pyrylium as a starting material. The molecular structure was determined by 1H NMR, 13C NMR, and high resolution mass spectrometry. The molecular recognition properties of L have been investigated through fluorescence titration experiments. The results indicate that L has sensitive and selective fluorescent response to NO3- among other different anions. Significant enhancements in the fluorescence intensity of L were observed when various concentrations of NO3- were added, while other competing anions have a quenching effect towards the initial fluorescence of solution. The fluorescence titration spectra shows that the bonding stoichiometry between receptor L and NO3- is 1 : 1 as a supramolecular complexes (1gK = 5 ± 0.02). The chemosensing properties of L were evaluated through quantum chemical calculations and the variable temperature 1H NMR titration. These results suggested that L has strong binding affinity towards NO3- with high selectivity, which may be ascribed to the specific hydrogen bonding between the L and active H atom of the bipyrydinium salts. The interaction between L and NO3- made the complex more planar compared with L giving rise to enhanced fluorescence and specific selectivity towards NO3-.

Evaluation of meropenem regimens suppressing emergence of resistance in Acinetobacter baumannii with human simulated exposure in an in vitro intravenous-infusion hollow-fiber infection model.

The emergence of resistance to carbapenems in Pseudomonas aeruginosa can be suppressed by optimizing the administration of meropenem. However, whether the same is true for Acinetobacter baumannii is not fully understood. We assessed the bactericidal activity of meropenem and its potency to suppress the emergence of resistance in A. baumannii with human simulated exposure in an in vitro intravenous-infusion hollow-fiber infection model (HFIM). Two clinical strains of carbapenem-susceptible multidrug-resistant A. baumannii (CS-MDRAB), CSRA24 and CSRA91, were used, and their MICs and mutant prevention concentrations (MPCs) were determined. Six meropenem dosage regimens (0.5, 1.0, or 2.0 g given every 8 h [q8h] with a 0.5-h or 3-h infusion for seven consecutive days) were simulated and then evaluated in the HFIM. Both the total population and resistant subpopulations of the two strains were quantified. Drug concentrations were measured by high-performance liquid chromatography. All dosage regimens, except for the lowest dosage (0.5 g for both the 0.5-h and 3-h infusions), showed 3-log CFU/ml bacterial killing. Dosage regimens of 2.0 g with 0.5-h and 3-h infusions exhibited an obvious bactericidal effect and suppressed resistance. Selective amplification of subpopulations with reduced susceptibility to meropenem was suppressed with a percentage of the dosage interval in which meropenem concentrations exceeded the MPC (T>MPC) of ≥20% or with a ratio of T>MPC to the percentage of the dosage interval in which drug concentrations are within the mutant selection window of ≥0.25. Our in vitro data support the use of a high dosage of meropenem (2.0 g q8h) for the treatment of severe infection caused by CS-MDRAB.

A synergic effect of sodium on the phase transition of tungsten-doped vanadium dioxide.

A synergic effect of sodium on the metal-insulator transition temperature reduction of tungsten-doped vanadium dioxide is noted. With the assistance of sodium, doping with tungsten yields an extra depression in phase temperature of 6-12 °C over that of 20-26 °C per at% of tungsten.

Preparation of genetically or chemically engineered exosomes and their therapeutic effects in bone regeneration and anti-inflammation.

The treatment of bone or cartilage damage and inflammation-related diseases has been a long-standing research hotspot. Traditional treatments such as surgery and cell therapy have only displayed limited efficacy because they can't avoid potential deterioration and ensure cell activity. Recently, exosomes have become a favorable tool for various tissue reconstruction due to their abundant content of proteins, lipids, DNA, RNA and other substances, which can promote bone regeneration through osteogenesis, angiogenesis and inflammation modulation. Besides, exosomes are also promising delivery systems because of stability in the bloodstream, immune stealth capacity, intrinsic cell-targeting property and outstanding intracellular communication. Despite having great potential in therapeutic delivery, exosomes still show some limitations in clinical studies, such as inefficient targeting ability, low yield and unsatisfactory therapeutic effects. In order to overcome the shortcomings, increasing studies have prepared genetically or chemically engineered exosomes to improve their properties. This review focuses on different methods of preparing genetically or chemically engineered exosomes and the therapeutic effects of engineering exosomes in bone regeneration and anti-inflammation, thereby providing some references for future applications of engineering exosomes.

Catechol-Based Porous Organic Polymers for Effective Removal of Phenolic Pollutants from Water.

Phenolic pollutants released from industrial activities seriously damage natural freshwater resources, and their elimination or reduction to safe levels is an urgent challenge. In this study, three catechol-based porous organic polymers, CCPOP, NTPOP, and MCPOP, were prepared using sustainable lignin biomass-derived monomers for the adsorption of phenolic contaminants in water. CCPOP, NTPOP, and MCPOP showed good adsorption performance for 2,4,6-trichlorophenol (TCP) with theoretical maximum adsorption capacities of 808.06 mg/g, 1195.30 mg/g, and 1076.85 mg/g, respectively. In addition, MCPOP maintained a stable adsorption performance after eight consecutive cycles. These results indicate that MCPOP is a potential material for the effective treatment of phenol pollutants in wastewater.

Efficacy of Zidovudine-Amikacin Combination Therapy In Vitro and in a Rat Tissue Cage Infection Model against Amikacin-Resistant, Multidrug-Resistant Enterobacteriales.

Multidrug-resistant (MDR) Enterobacteriales infections have become an urgent global threat to public health. The aim of this study was to evaluate the efficacy of zidovudine-amikacin combination therapy in vitro and in vivo. Molecular characteristics and antibiotic resistance profiles of 53 amikacin-resistant MDR, extensively drug-resistant (XDR), or pan-drug-resistant (PDR) clinical isolates were examined via PCR and susceptibility testing. Checkerboard assays were performed for these 53 isolates to assess in vitro synergistic effects of the zidovudine-amikacin combination, and static time-kill experiments were performed for four XDR or PDR Enterobacteriales isolates. A Galleria mellonella model and a rat tissue cage infection model were established to assess in vivo synergistic effects. The aac(6')-Ib gene was detected in 25 (47.2%) isolates, followed by armA in 5 (9.4%) isolates, rmtB in 27 (50.9%) isolates, and rmtC in 3 (5.8%) isolates. Checkerboard assays showed the synergy of this combination against 38 (71.7%) isolates. The time-kill assays further confirmed that zidovudine strongly synergized with amikacin against four XDR or PDR Enterobacteriales isolates. The Galleria mellonella model study showed that the survival benefit of zidovudine-amikacin combination therapy was significantly better than that of monotherapy for those four Enterobacteriales isolates. Furthermore, the rat tissue cage infection model study showed that zidovudine-amikacin combination therapy displayed more potent bactericidal activity than monotherapy after 3 and 7 days of treatment for the above four isolates. Our data support the idea that the zidovudine-amikacin combination could be a plausible alternative therapy against infections with amikacin-resistant MDR Enterobacteriales, especially with XDR and PDR Enterobacteriales. IMPORTANCE Our study revealed for the first time that the zidovudine-amikacin combination shows a significant bactericidal effect against amikacin-resistant MDR, XDR, and PDR Enterobacteriales. Second, using in vitro and in vivo approaches, our study showed that zidovudine strongly synergized with amikacin against amikacin-resistant MDR Enterobacteriales isolates. Most importantly, with regard to survival benefit, pharmacokinetics, and bactericidal effects, our in vivo experiment demonstrated the effectiveness of zidovudine-amikacin.

Selective sensing of H2PO4(-) (Pi) driven by the assembly of anthryl pyridinium ligands.

Synthesis of a simple amidopyridinium-based sensor (F1) and its fluorescence behavior toward H(2)PO(4)(-) (Pi) were investigated. The anthryl group in F1 exhibited a strong excimer emission via Pi-directed assembly of F1; other anions showed a negligible effect. The Pi-induced assembly of F1 was rationalized by photophysical experiments and DFT calculation.

rac-7,7',9,9'-Tetra-phenyl-9a,9a'-bi(7,8,9,9a-tetra-hydro-6aH-penta-leno[1,2,3-ij]naphthalen-8-one).

The racemic title compound, C(54)H(38)O(2), consists of two C-linked penta-leno[1,2,3-ij]naphthalenone moieties, the crowded aryl ring substitution on the cyclo-pentane rings forcing the two segments to assume a conformation which has pseudo-twofold rotational symmetry, with a dihedral angle between the naphthalene substituent groups of 55.30 (8)°. In each segment, the two phenyl rings have different conformational orientations, with inter-ring dihedral angles of 34.7 (2) and 49.63 (16)°. Each cyclo-pentane ring has the same relative configuration in its four chiral centres and together with the fused naphthalene ring assumes an overall chair-like conformation.

A pillar[5]arene-based covalent organic framework with pre-encoded selective host-guest recognition.

It is highly desirable to maintain both permanent accessible pores and selective molecular recognition capability of macrocyclic cavitands in the solid state. Integration of well-defined discrete macrocyclic hosts into ordered porous polymeric frameworks (e.g., covalent organic frameworks, COFs) represents a promising strategy to transform many supramolecular chemistry concepts and principles well established in the solution phase into the solid state, which can enable a broad range of practical applications, such as high-efficiency molecular separation, heterogeneous catalysis, and pollution remediation. However, it is still a challenging task to construct macrocycle-embedded COFs. In this work, a novel pillar[5]arene-derived (P5) hetero-porous COF, denoted as P5-COF, was rationally designed and synthesized. Featuring the unique backbone structure, P5-COF exhibited selective adsorption of C2H2 over C2H4 and C2H6, as well as significantly enhanced host-guest binding interaction with paraquat, in comparison with the pillar[5]arene-free COF analog, Model-COF. The present work established a new strategy for developing COFs with customizable molecular recognition/separation properties through the bottom-up "pre-porous macrocycle to porous framework" design.

Preparation, characterization and antioxidant activity of protocatechuic acid grafted carboxymethyl chitosan and its hydrogel.

In this study, protocatechuic acid (PCA) was grafted onto carboxymethyl chitosan (CMCS) via EDC/NHS to improve the antioxidant effect. The grafting ratio of PCA-g-CMCS conjugates could be controlled by adjusting the pH value and feed ratio of raw materials. The conjugates exhibited similar pH sensitivity to CMCS and showed dramatic enhancements of DPPH and ABTS radicals scavenging activities, total antioxidant capacity, reducing power, and Fe2+-chelating activity. Three-dimensional porous PCA-g-CMCS hydrogel was prepared by lyophilization and secondary cross-linking. The shaped hydrogel preserved its antioxidant activity, and the sustained release of PCA-containing degraded fragment from biodegradable hydrogel could be achieved with the aid of lysozyme in vitro (15 days). PCA-g-CMCS hydrogel also showed excellent biocompatibility and protective effect on H2O2-induced oxidative damage in SH-SY5Y cells. These results suggested that PCA-g-CMCS conjugates and its hydrogel would appear to be a promising oxidation-resistant material for applications such as drug release and tissue engineering.

Supramolecularly Poly(amidoxime)-Loaded Macroporous Resin for Fast Uranium Recovery from Seawater and Uranium-Containing Wastewater.

Uranium is an extremely abundant resource in seawater that could supply nuclear fuel for over the long-term, but it is tremendously difficult to extract. Here, a new supramolecular poly(amidoxime) (PAO)-loaded macroporous resin (PLMR) adsorbent has been explored for highly efficient uranium adsorption. Through simply immersing the macroporous resin in the PAO solution, PAOs can be firmly loaded on the surface of the nanopores mainly by hydrophobic interaction, to achieve the as-prepared PLMR. Unlike existing amidoxime-based adsorbents containing many inner minimally effective PAOs, almost all the PAOs of PLMR have high uranium adsorption efficiency because they can form a PAO-layer on the nanopores with molecular-level thickness and ultrahigh specific surface area. As a result, this PLMR has highly efficient uranium adsorbing performance. The uranium adsorption capacity of the PLMR was 157 mg/g (the UPAO in the PLMR was 1039 mg/g), in 32 ppm uranium-spiked seawater for 120 h. Additionally, uranium in 1.0 L 100 ppb U-spiked both water and seawater can be removed quickly and the recovery efficiency can reach 91.1 ± 1.7% and 86.5 ± 1.9%, respectively, after being filtered by a column filled with 200 mg PLMR at 300 mL/min for 24 h. More importantly, after filtering 200 T natural seawater with 200 g PLMR for only 10 days, the uranium-uptake amount of the PLMR reached 2.14 ± 0.21 mg/g, and its average uranium adsorption speed reached 0.214 mg/(g·day) which is very fast among reported amidoxime-based adsorbents. This new adsorbent has great potential to quickly and massively recover uranium from seawater and uranium-containing wastewater. Most importantly, this work will provide a simple but general strategy to greatly enhance the uranium adsorption efficiency of amidoxime-functionalized adsorbents with ultrahigh specific surface area via supramolecular interaction, and even inspire the exploration of other adsorbents.