Latest ArticlesTsaokols A (1) and B (2), two complicated flavanol-monoterpenoid hybrids, were isolated from the dried fruits of Amomum tsao-ko under the guidance of LCMS and bioassay. Their structures were determined by extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 shared a flavanol backbone fused with 5/7 and 5/6 bicyclic monoterpenoid scaffolds, which were biogenetically condensed by Michael addition and acetalization. Compounds 1 and 2 exhibited significant α-glucosidase inhibitory activity with IC50 values of 18.8 and 38.6 μmol/L (acarbose, IC50 = 213 μmol/L). Docking study supported the strong interactions of 1 and 2 bonding with enzyme by mainly hydrophobic and hydrogen-bond effects. Compounds 1 and 2 could be fast distinguished by the diagnostic ions at m/z 289 and 313 in negative MS2 experiments.
Three novel polycyclic polyprenyled acylphloroglucinols, Hyperscabins A-C, were obtained from the aerial parts of Hypericum scabrum. They featured an unprecedented 5, 5-spiroketal subunit with the loss of C-2' carbonyl in the phloroglucinol ring. Their structures were characterized by extensive spectroscopic analyses, NMR calculations with DP4+ analysis, calculated electronic circular dichroism (ECD) spectra and the application of modified Mosher's methods. In the assay of [3H]-5-HT and [3H]-NE reuptake inhibition, compounds 1 and 2 showed good inhibitory activity (81.8% and 83.2%) in 10 μmol/L. In addition, compound 1 significantly increased cell viability in the experiment of oxygen and glucose deprivation/deoxygenation.
Potassium-ion batteries (PIBs) are attracted tremendous interest for large-scale energy storage systems (ESSs) owing to their economic merits. However, the main challenges of the PIBs are sluggish K-ion diffusion and large volume variations in the potassium repeated intercalation/deintercalation. Herein, mesoporous carbon nanosheet-assembled flowers (abbreviated as F-C) are designed as an original anode for superior-performance PIBs. Specifically, the F-C anode exhibits a high K-storage capacity (e.g., 381 mAh/g at 50 mA/g during the 2nd cycle), excellent rate performance (e.g., 101 mAh/g at 2.0 A/g) and superior long cycle capability. Such excellent K-ion storage property is largely benefited from the large surface area (~141 m2/g) and reasonable pore volume (0.465 cm3/g), which not only stimulates rapid K-ions diffusion and relieves the huge volume strain, but also exposes extensive active sites for K-ion capacitive storage.
Luminescent conjugated network polymer is one of the most promising chemo-sensors owing to their good chemical/optical stability and multiple functionalization. Herein, three conjugated network polymers were prepared by using aggregation-induced emission active 1, 1, 2, 2-tetrakis(4-formyl-(1, 1'-biphenyl))-ethane (TFBE) unit as monomer and hydrazine as linker. Through regulating the synthetical condition, the polymeric network can form either uniform two-dimensional azine-linked nanosheets (A-NS), conjugated microporous polymers (A-CMP) or covalent organic frameworks (A-COF). All of these polymers exhibited good stability and high fluorescence quantum efficiency with the quantum yield of 6.31% for A-NS, 5.26% for A-CMP, and 5.80% for A-COF, as well as fast and selective fluorescence quenching response to 2, 4, 6-trinitrophenol (TNP). And the best TNP sensing performance with the Stern-Volmer constants (Ksv) values up to 8×105 L/mol and a detection limit of 0.09 μmol/L was obtained for A-NS. The study explores various strategies to construct conjugated polymers with different nanoarchitectures based on the same building block for sensitive detection of explosives.
The abnormal aggregation of amyloid-beta (Aβ) has been widely believed to play an important role in the pathogenesis of Alzheimer's disease (AD), which is also recognized as one of the main biomarkers for AD diagnosis. The peptide sequence Lys-Leu-Val-Phe-Phe (KLVFF) is considered as the main driver of the fibrillation of Aβ, which also can be utilized to target Aβ and inhibit its aggregation. In this study, KLVFF and Fmoc-KLVFF fluorescent nanoparticles were self-assembled through zinc coordination and π-π stacking. The recognition of Aβ aggregates including oligomers and fibrils by fluorescent nanoparticles can be realized through aromatic, hydrophobic, and hydrogen-bond interactions. The fluorescent nanoprobes can distinguish Aβ aggregation formats and detect Aβ at the limit of 1 pg/mL (S/N = 3). Hence, the detection of Aβ aggregates by fluorescent peptide nanoparticles has great potential for AD diagnosis and progression prediction.
An electrochemical amino-azidation of 2-aminostyrene with sodium azide (NaN3) was developed, which can be carried out smoothly in water under metal-free condition, affording a series of 3-azido indolines with high yields.
Multishelled hollow structures have drawn increasing interest because of their peculiar compartmentation environments and physicochemical properties. In this work, deformable double-shelled hollow mesoporous organosilica nanocapsules (DDHMONs) were successfully synthesized by a multi-interfacial etching strategy. The obtained DDHMONs have a double-shelled structure with aninorganic-organic hybrid framework, a uniform outer layer (~320 nm) and inner layer (~180 nm), ordered mesochannels (~2.21 nm), and a large specific surface area (~1233 m2/g). In vitro toxicity tests show that the DDHMONs have excellent biocompatibility when coincubated with human breast cancer cells. In addition, the anticancer substance doxorubicin (DOX) can be highly loaded in DDHMONs (~335 μg/mg). The results from flow cytometry together with confocal laser scanning microscopy show that DOX can be efficiently delivered into MCF-7 cells by DDHMONs, thus improving chemotherapeutic efficiency and demonstrating that DDHMONs have potential nanomedicine applications as anticancer agents.
A new kind of emissive small-molecular organic cage has been developed via the combination of coupling and condensation reactions, which shows outstanding solubility, structural stability and potential spatial isomeric chirality. Interestingly, through the introduction of proper donor and acceptor units, this emissive organic cage is the first among organic cages to exhibit red aggregation-induced delayed fluorescence with photoluminescence emission at 603 nm. The finding not only expands the types of emissive small-molecular organic cages, but also represents an important step for further development of red delayed fluorescence materials with good solubility and aggregation-induced emission feature.
Using the global particle-swarm optimization method and density functional theory, we predict a new stable two-dimensional layered material: MgSiP2 with a low-buckled honeycomb lattice. Our HSE06 calculation shows that MgSiP2 is an indirect-gap semiconductor with a band-gap of 1.20 eV, closed to that of bulk silicon. More remarkably, MgSiP2 exhibits worthwhile anisotropy along with electron and hole carrier mobility. A ultrahigh electron mobility is even up to 1.29×104 cm2 V-1 s-1, while the hole mobility is nearly zero along the a direction. The large difference of the mobility between electron and hole together with the suitable band-gap suggest that MgSiP2 may be a good candidate for solar cell or photochemical catalysis material. Furthermore, we explore MgSiP2 as an anode for sodium-ion batteries. Upon Na adsorption, the semiconducting MgSiP2 transforms to a metallic state, ensuring good electrical conductivity. A maximum theoretical capacity of 1406 mAh/g, a small volume change (within 9.5%), a small diffusion barrier (~0.16 eV) and low average open-circuit voltages (~0.15 V) were found for MgSiP2 as an anode for sodium-ion batteries. These results are helpful to deepen the understanding of MgSiP2 as a nanoelectronic device and a potential anode for Na-ion batteries.
Most recently, cobalt sulfide (CoS) nanospheres (NSs) have been demonstrated as an ideal high-efficient photothermal agent for tumor elimination. However, the surface of CoS NSs is lack of functional chemical groups or active radicals to incorporate therapeutic agents, which tremendously hinders their versatile utilization in medical field. Here, surface activation of CoS NSs was realized through the growth of polydopamine (PDA) in situ via alkaline-triggered polymerization. Upon the formation of CoS@PDA NSs, thiol-polyethylene glycol (SH-PEG) and chemotherapeutic agent of doxorubicin (DOX) were loaded onto the particle surface by means of π-π electrostatic interaction and Michael addition reactions. As-synthesized CoS@PDA/PEG/DOX (CoPPD) NSs exhibited an admirable photothermal property and high loading capacity of DOX (44.6%). Furthermore, drug release can be accelerated under a more acidic pH condition mimicking tumor microenvironment (TME), ascribed to the protonation of amino group in DOX molecules. Finally, a strong chemotherapeutic-enhanced photothermal therapeutic effect was demonstrated toward solid tumor under near-infrared (NIR) light irradiation without causing significant systemic toxicity. In this regard, this paradigm may offer valuable guidance for the design of multifunctional CoS-based nanoagents for medical treatment.