Clinical translation of curcumin has been highly obstructed by the rapid degradation and poor tissue absorption of this agent. Herein, we report on the generation of supramolecular curcumin ...nanoagents through amino acid coordination driven self‐assembly to simultaneously increase the biological stability and tumor accumulation of curcumin. The biological stability of curcumin was significantly improved both through coordination and through molecular stacking. The sizes of these nanoagents can be readily manipulated to facilitate tumor accumulation. These favorable therapeutic features, together with high drug‐loading capacities and responses to pH and redox stimuli, substantially enhanced the antitumor activity of curcumin without discernible side effects. Hence, supramolecular curcumin nanoagents may hold promise in moving forward the clinical application of curcumin as an effective anticancer drug.
Special agents on the job: Supramolecular curcumin nanoagents were fabricated by amino acid coordination driven self‐assembly (see picture). The biological stability of curcumin was significantly improved through both coordination and molecular stacking in the nanoagents, the size of which could be readily manipulated. These favorable therapeutic features substantially enhanced the antitumor activity of curcumin without discernible side effects.
Solid-state nanopores have been employed as useful tools for single molecule analysis due to their advantages of easy fabrication and controllable diameter, but selectivity is always a big concern ...for complicated samples. In this work, functionalized magnetic core–shell Fe3O4–Au nanoparticles, which acted as a molecular carrier, were introduced into nanopore electrochemical system for microRNA sensing in complicated samples with high sensitivity, selectivity and signal-to-noise ratio (SNR). This strategy is based on the specific affinity between neutral peptide nucleic acids (PNA)-modified Fe3O4–Au nanoparticles and negative miRNA, and the formation of negative Fe3O4–Au–PNA–miRNA complex, which can pass through the nanopore by application of a positive potential and eliminate neutral Fe3O4–Au–PNA complex. To detect miRNA in complicated samples, a magnet has been used to separate Fe3O4–Au–PNA–miRNA complex with good selectivity. We think this is a facile and effective method for the detection of different targets at single molecular level, including nucleic acids, proteins, and other small molecules, which will open up a new approach in the nanopore sensing field.
The development of highly active and durable inexpensive electrocatalysts for hydrogen evolution reaction (HER) is still a formidable challenge. Herein, an ordered hexagonal-closed-packed (hcp)-Ru ...nanocrystal coated with a thin layer of N-doped carbon (hcp-Ru@NC) was fabricated through the thermal annealing of polydopamine (PDA)-coated Ru nanoparticle (RuNP@PDA). As an alternative to Pt/C catalyst, the hcp-Ru@NC nanocatalyst exhibited the small overpotential of 27.5 mV at a current density of 10 mA cm–2, as well as long-term stability for HER in acid media. Interestingly, the HER performance of hcp-Ru is highly dependent on its crystallinity. The calculation from density functional theory (DFT) revealed that the difference in HER activity over various exposed surface causes the crystallinity-dependent property of hcp-Ru. The results provided clues to guide the design of Ru-based inexpensive HER electrocatalyst.
A fiber optic surface plasmon resonance (FOSPR) sensor was developed for detection of Escherichia coli O157:H7 (E. coli O157:H7) in water and juice, based on antimicrobial peptides (AMP), Magainin I, ...as recognition elements and silver nanoparticles-reduced graphene oxide (AgNPs-rGO) nanocomposites assisted signal amplification. The uniform AgNPs-rGO was fixed on the surface of optical fiber and covered with gold film. Not only was the SPR response greatly enhanced, but also the AgNPs was prevented from being oxidized. The FOSPR showed a sensitivity of about 1.5 times higher than that fabricated only with gold film. In the assay, Magainin I, immobilized on the surface of gold film, could specifically capture E. coli O157:H7, resulting in the wavelength shift of the SPR absorption peak. Under the optimized conditions, the SPR resonance wavelength exhibited a good linear relationship with natural logarithm of the target bacteria concentration in the range of 1.0 × 103 to 5.0 × 107 cfu/mL with the detection limit of 5.0 × 102 cfu/mL (S/N = 3). The FOSPR sensor showed good specificity for E. coli O157:H7 detection compared to other bacteria similar to the target bacterial species. Furthermore, the FOSPR sensor was successfully applied to the detection of E. coli O157:H7 in water, fruit and vegetable juice with the satisfactory recoveries of 88–110%. This assay for E. coli O157:H7 detection possesses high sensitivity, good selectivity, reproducibility and stability. In addition, the AMP based SPR biosensing methodology could be extended to detect a wide variety of foodborne pathogens. Therefore, the versatile method might become a potential alternative tool in food analysis and early clinical diagnosis.
•A label-free FOSPR sensor for detection of E. coli O157:H7 with a LOD of 5 × 102 cfu/mL.•AgNPs-rGO composites bounded to the fiber probe surface enhance the sensitivity of FOSPR sensor.•Magainin I as a recognition element, can directly detect E. coli O157:H7 cells without complex DNA extraction.•The methodology can detect E. coli O157:H7 in water and juice samples with acceptable results.
Nanopores have become one of the most important tools for single-molecule sensing, but the challenge for selective detection of specific biomolecules still exists. In this contribution, we develop a ...new technique for sensing carcinoembryonic antigen (CEA), one of the important cancer biomarkers, using solid-state nanopores as a tool. The method is based on the specific affinity between aptamer (Apt) modified magnetic Fe3O4–Au nanoparticles (MNPs) and CEA, and the formed CEA–Apt–MNPs and remaining Apt–MNPs can transport the nanopores by applying a positive potential after magnetic separation. Due to the obvious particle size difference between CEA–Apt–MNPs and Apt-MPs, their corresponding blockage signals could be distinguished completely by the degree of the current decline. Moreover, the frequency of the blockage signals for CEA–Apt–MNPs is proportional to the concentration of CEA within certain limits, indicating that our designed nanopore sensing strategy can quantitatively detect CEA in complex samples. This work demonstrates that our designed nanopore-based strategy can be used for CEA sensing with good selectivity and sensitivity and also can be used to analyze other protein biomarkers for early diagnosis and monitoring of cancer, though the detection limit (0.6 ng/mL) is not relatively low. In future works, we plan to improve our detection limit by the improvement of the nanopipette preparation technology and detection method.
3,4-dihydro-2H-1,2,4,3-triazaborol-3-yl-lithium 3 was synthesized and fully characterized. The 11B NMR spectrum, X-ray diffraction analysis, and computational studies revealed the ionic nature of the ...B–Li bond, and indeed 3 displays nucleophilic property which allowed preparation of a series of 1,2,4,3-triazaborol-3-yl-metal complexes (Al; 5, Au; 6, Zn; 7, Mg; 8, Sb; 9, and Bi; 10). 3 reacted with CO (1 atm) and various isonitriles under ambient condition, and mechanistic study suggests that the reactions with CO and aryl isonitriles proceed via an insertion of CO and isonitrile carbon into the B–Li bond followed by isomerization to yield transient carbene species, one of which was confirmed by trapping with S8. With PhNC, compounds 5 and 7·(thf) underwent exchange of THF molecule coordinating to the metal center with isonitrile, whereas insertion of isonitrile carbon occurred at the B–Bi bond in 10 which afforded stable bismuth (boryl)iminomethane 20.
Artificially improving traits of cultivated alfalfa (Medicago sativa L.), one of the most important forage crops, is challenging due to the lack of a reference genome and an efficient genome editing ...protocol, which mainly result from its autotetraploidy and self-incompatibility. Here, we generate an allele-aware chromosome-level genome assembly for the cultivated alfalfa consisting of 32 allelic chromosomes by integrating high-fidelity single-molecule sequencing and Hi-C data. We further establish an efficient CRISPR/Cas9-based genome editing protocol on the basis of this genome assembly and precisely introduce tetra-allelic mutations into null mutants that display obvious phenotype changes. The mutated alleles and phenotypes of null mutants can be stably inherited in generations in a transgene-free manner by cross pollination, which may help in bypassing the debate about transgenic plants. The presented genome and CRISPR/Cas9-based transgene-free genome editing protocol provide key foundations for accelerating research and molecular breeding of this important forage crop.
Boranes have long been known as the archetypal Lewis acids owing to an empty p-orbital on the boron centre. Meanwhile, Lewis basic tricoordinate boranes have been developed in recent years. Here we ...report the synthesis of an annulated 1,4,2,5-diazadiborinine derivative featuring boron atoms that exhibit both Lewis acidic and basic properties. Experimental and computational studies confirmed that two boron atoms in this molecule are spectroscopically equivalent. Nevertheless, this molecule cleaves C-O, B-H, Si-H and P-H bonds heterolytically, and readily undergoes 4+2 cycloaddition reaction with non-activated unsaturated bonds such as C=O, C=C, C≡C and C≡N bonds. The result, thus, indicates that the indistinguishable boron atoms in 1,4,2,5-diazadiborinine act as both nucleophilic and electrophilic centres, demonstrating ambiphilic nature.
A zwitterionic boraalkenyl boronium 3 was synthesized by reduction of cyclic (alkyl)(amino)carbene (cAAC) and trimethylphosphine (PMe3)‐coordinated tetrabromodiborane 2 with KC8 in the presence of ...PMe3. Further reduction of 3 led to the formation of neutral allenic diborene 4. X‐ray diffraction and computational studies revealed that 4 features the cumulated C=B and B=B double bonds. The reaction of 4 with four isonitrile molecules afforded a heterocycle 5 with the B2C3 five‐membered ring, via a complete scission of the B=B bond of 4.
Multiple bonds: Reduction of a zwitterionic boraalkenyl boronium with potassium graphite afforded a neutral allenic diborene. X‐ray diffraction and computational studies elucidated that the allenic diborene features the cumulated C=B and B=B double bonds. A complete scission of the B=B bond was achieved by reaction with isonitriles.
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