Latest ArticlesFluorescence imaging-guided photodynamic therapy holds great promise for application in precise cancer diagnosis and treatment, which has motivated high requirements for phototheranostic agents. However, current photosensitizers (PSs) generally face limitations such as short emission wavelength and inadequate reactive oxygen species (ROS) production. Aggregation-caused quenching issue also hinders the phototheranostic efficiency of PSs. Herein, the π-bridge modulation strategy is proposed to construct ionic PSs with enhanced bioimaging and therapeutic outcomes. Two donor-π-acceptor (D-π-A) molecules TPCPY and TFCPY were obtained by incorporating phenyl and furan units as π-bridge, respectively. Both PSs feature aggregation-induced near-infrared emission. Under light irradiation, TPCPY and TFCPY can produce both type Ⅰ and Ⅱ ROS. Introducing furan ring in TFCPY enhances the ROS generation capacity by type Ⅰ photosensitization process, which is consistent with the reduced energy gap between singlet and triplet states from theoretical calculation. Furthermore, TFCPY can achieve quick cellular uptake, accumulate in mitochondria, and then efficiently kill cancer cells, which is superior to TPCPY. Consequently, TFCPY exhibited good antitumor outcomes and excellent in vivo fluorescence imaging ability. This work provides an efficient molecular engineering of introducing heterocycles into the D-π-A skeleton to develop high-performance PSs with both type Ⅰ and Ⅱ ROS generation.
The significance of axial chiral compounds in asymmetric organic catalysis, functional materials, and pharmaceutical useful molecules has encouraged advancements in the atroposelective synthesis of such compounds. Herein, we report the first atroposelective construction of axially chiral N-aryl benzimidazoles catalyzed by a polymer-supported chiral phosphoric acid. A varied library of atropisomers has been synthesized in 30%-96% yield with 58%-98% enantiomeric excess (ee) under a straightforward reaction setup (without the use of molecular sieves). Notably, even after 12 cycles, the immobilized catalyst maintained its reactivity and selectivity (TON > 540).
Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is an attractive technology for the visualization of metabolite distributions in tissues. However, detection and identification of low-abundance or poorly ionized metabolites remains challenging. Although on-tissue chemical derivatization (OTCD) holds great promise for improving MALDI MS detection sensitivity and selectivity by modification of specific chemical groups, the available methods for subsequent metabolite annotation are limited. Herein, a laser-assisted chemical transfer (LACT)-based parallel OTCD strategy was established for visualizing and annotating carbonyl metabolites in murine brain tissues. Girard's T and Girard's P reagents were applied for parallel OTCD to generate the characteristic m/z pairs with a 19.969 Da mass shift (±0.020 Da tolerance) for rapid recognition of derivatized metabolites. The similarity of spatial distribution patterns of each m/z pair was further statistically evaluated to remove the ambiguous annotations due to the occurrence of interference compounds. As a result, 90 ion pairs were annotated as candidate carbonyl metabolites, 66 were previously known and 24 were potential unreported carbonyls. Furthermore, the spatial alterations of carbonyl metabolites in the ischemic rat brain were successfully visualized and characterized, including small molecule aldehydes and ketones, long-chain fatty aldehydes, and monosaccharides. This further emphasizes great potential of parallel OTCD strategy for efficient and confident molecular annotation of spatial submetabolomics data associated with brain diseases.
Lithium metal batteries, with their light mass anode and high theoretical specific capacity of 3860 mAh/g, have great potential for development in achieving high energy density. However, the generation of lithium dendrites and the loss of dead lithium pose a serious threat to the safety and long-cycle stability of batteries. Herein, we utilize the Lewis acid-base interaction principle for lithium-ion migration regulation. Through loading solid-acids onto molecular sieves to immobilize Lewis base (PF6−), we achieve accelerated dissociation of lithium salts and successfully increase the lithium ion transference number to 0.44. Lewis acid-base interaction helps lithium metal batteries achieve more uniform lithium deposition, with an average CE improved to 92.8%. The symmetrical cells can be plated/stripped stably for more than 800 h of cycling. Full cell with high surface-loaded LFP cathode (14 mg/cm2) exhibits impressively high capacity retention of 90.7% after 120 cycles at 0.5 C.
Electrochemical nitrate reduction (NO3RR) offers a promising avenue for treating nitrate-contaminated water and recovering ammonia (NH3), yet the complexities of direct electron transfer (DET) and hydrogen atom transfer (HAT) mechanisms crucial for efficiency remain elusive. This study bridges the gap with a combined experimental and theoretical approach, elucidating the impact of catalyst structure on NO3RR pathways. We discover that catalysts favoring strong NO3− adsorption and efficient water dissociation were more inclined towards DET, enhancing denitrification. The Fe@Fe3O4/FF cathode, leveraging the synergistic interplay between metallic Fe and Fe3O4, excelled in NO3RR via DET, achieving an NH3 yield of 0.28 mmol h−1 cm−2 and a Faradaic efficiency of 95.7% for NH3 at -1.6 V (vs. SCE), with minimal nitrite accumulation at 100 mmol/L nitrate. Conversely, the Fe/FF and Fe3O4/CC cathodes showed reduced NH3 production and increased nitrite levels, attributed to the lack of Fe3O4 and metallic Fe, respectively, resulting in a dominant HAT mechanism. Moreover, Fe@Fe3O4/FF facilitated complete denitrification in real wastewater treatment by harnessing Cl− for electrochemically mediated breakpoint chlorination. This research not only deepens our understanding of NO3RR mechanisms but also paves the way for designing superior nitrate reduction catalysts.
Degradation of nitrobenzene (NB) via Fenton-like reaction is considered as an efficient approach for contaminated groundwater remediation. However, the poor stability of H2O2 limits the application of traditional Fenton reactions in soil and groundwater due to the transportation risks of H2O2. In this study, we synthesized a controlled release nano calcium peroxide (nCP) by coating it with polydopamine (PDA) as a solid H2O2 to construct a Fe(Ⅱ)/PDA@nCP Fenton-like system for contaminants degradation. The phenol-quinone transformations of catechol groups on the PDA surface facilitated the Fe(Ⅱ)/Fe(Ⅲ) cycle, resulting in enhanced generation of hydroxyl radicals (HO) and effective long-term degradation of NB. Moreover, the PDA shell modulated the nCP decomposition rate and inhibited sharp pH fluctuations, and the NB removal efficiency was achieved up to 96.8% at pH ranging from 3.0 to 9.0. This study demonstrated the promising application potential of PDA@nCP as a solid-controlled release H2O2 source in Fenton-like system for groundwater contamination remediation.
Receptor tyrosine kinases (RTKs) are biological enzymes expressed on cell membranes that can influence cellular signaling, and their overexpression in tumor cells makes them a key route to assess relevant tumor processes. The development of a delivery system that targets and accumulates in RTKs overexpressing-cells at the on-target site is significant for the monitoring of tumor progression and clinical applications through longer tumor site signaling response under low injection frequency. Here, a host-guest nanoscale fluorescent probe SNI@ZIF-8 based on zeolitic imidazolate framework-8 (ZIF-8) and a fluorescent probe SNI constructed from receptor tyrosine kinase inhibitor was proposed and prepared for targeting RTKs and enabling prolonged fluorescence imaging in vivo. The folded conformation of the probe SNI resulted in low background fluorescence, and the unfolding of the SNI conformation upon insertion of the RTKs active pocket showed significant fluorescence enhancement thus enabling real-time detection of RTKs. The host-guest system SNI@ZIF-8 could release guest molecules due to the presence of the enzyme, emphasizing the reporting of stable fluorescent signals over time under low injection frequency. SNI@ZIF-8 could provide a signal response on the cell membrane of RTKs overexpressing cells without interference from other substances, and provided a longer fluorescent signal than SNI at equivalent number of injections in tumor-bearing mice. The host-guest system SNI@ZIF-8, with its obvious tumor site enrichment ability and clear fluorescence imaging ability, could be successfully applied to the detection of RTKs on cell membranes in biological systems, providing a new strategy for determining the process of tumor development in clinical applications.
Asperfilasin A (1), featuring a unique 5/5 cyclopenta[c]pyrrol-one bicyclic core, represents a newly discovered skeletal cytochalasan isolated from Aspergillus flavipes. The enantioselective total synthesis was efficiently accomplished from the key intermediate (S)-6 with three contiguous stereocenters in 5 steps and the synthetic 1 induced G2/M-phase cell cycle arrest of HT29 cells and apoptosis of HL60 and NB4 cells by activation of caspase-3 and degradation of PARP. (S)-6, bearing three contiguous chiral centers, was efficiently constructed by a novel Nazarov cyclization reaction containing basic nitrogen, which was less developed, primarily due to the incompatibility of basic nitrogen under acidic reaction conditions. This reaction allows a wide range of pentadienone substrates containing basic nitrogen to undergo Nazarov cyclization in a single regioselective and diastereoselective manner and is capable of generating three stereocenters simultaneously. Furthermore, the mechanism of the Nazarov cyclization and the origin of the regio- and diastereoselectivity were elucidated by DFT calculations and deuteration experiments, providing valuable insights into the reaction and serving as a guide for future applications involving substrates containing basic nitrogen.
The asymmetric conjugate additions of aryl Grignard reagents to trisubstituted enones by chiral P, N ligand L6 with low catalyst loading (0.25–1.0 mol%) are disclosed. Chiral 2-ester chromanone and its analogs bearing a quaternary stereogenic centers at C2 position were produced in high to excellent yields, enantioselectivities and high turnover number. The notable features of this reaction include its broad substrate scope, complete 1, 4-addition regioselectivities, applicability to both batch and flow for large scale synthesis. This report develops an efficient strategy to apply aryl Grignard reagents in asymmetric 1, 4-conjugation reactions and provides a direct method to incorporate quaternary chiral centers toward the synthesis of biologically relevant chromanone derivatives.
Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport. The construction of these unique structures always requires new self-assembly behaviors with different building blocks, intriguing phenomena of colloidal chemistry. In this work, by delicately balancing the electrostatic repulsions between 2D inorganic nanosheets and the electrostatic adsorption with cations, we develop a general strategy to fabricate stable free-standing 1T molybdenum disulphide (MoS2) hydrogel membranes with abundant fluidic channels. Given the interpenetrating ionic transport network, the MoS2 hydrogel membranes exhibit a high-level capacitive performance 1.34 F/cm2 at an ultrahigh mass loading of 11.2 mg/cm2. Furthermore, the interlayer spacing of MoS2 in the hydrogel membranes can be controlled with ångström-scale precision using different cations, which can promote further fundamental studies and potential applications of the transition-metal dichalcogenides hydrogel membranes.
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