Latest ArticlesMetal-based catalysis, including homogeneous and heterogeneous catalysis, plays a significant role in the modern chemical industry. Heterogeneous catalysis is widely used due to the high efficiency, easy catalyst separation and recycling. However, the metal-utilization efficiency for conventional heterogeneous catalysts needs further improvement compared to homogeneous catalyst. To tackle this, the pursing of heterogenizing homogeneous catalysts has always been attractive but challenging. As a recently emerging class of catalytic material, single-atom catalysts (SACs) are expected to bridge homogeneous and heterogeneous catalytic process in organic reactions and have arguably become the most active new frontier in catalysis field. In this review, a brief introduction and development history of single-atom catalysis and SACs involved organic reactions are documented. In addition, recent advances in SACs and their practical applications in organic reactions such as oxidation, reduction, addition, coupling reaction, and other organic reactions are thoroughly reviewed. To understand structure-property relationships of single-atom catalysis in organic reactions, active sites or coordination structure, metal atom-utilization efficiency (e.g., turnover frequency, TOF calculated based on active metal) and catalytic performance (e.g., conversion and selectivity) of SACs are comprehensively summarized. Furthermore, the application limitations, development trends, future challenges and perspective of SAC for organic reaction are discussed.
Microneedles are considered to be an effective, convenient, non-invasive, biosafety and compliant medical technology for vaccinations, biomarker testing, medical aesthetics and other related fields. Nonetheless, further clinical and commercial translation of regular microneedles is hampered by challenges in manufacturability, cost variability, insufficient comfort, contamination and so on. Recent innovations in functional biomaterials and chemical engineering technologies have been applied to develop extensible and swellable hydrogel-forming microneedles, achieving precise and controlled drug delivery and localized sampling from the target tissues. In this review, we systematically summarize the latest development of the extensible and swellable hydrogel-forming microneedles, including deep point-of-care testing, drug deployment, wound healing and mucoadhesion improvement. In addition, further analysis of the challenges and prospects for clinical application of current strategies is well presented. It is believed that the combined efforts of engineering, material, pharmaceutical and clinical research will contribute to the future success of this clinical and commercial translation.
Chirality is one of the most important features of the nature. The recognition of enantiomers plays significant roles in the field of life science, pharmaceutical analysis and food chemistry. Among various recognition methods, fluorescence spectrometry has attracted much attention of researchers thanks to its high sensitivity and easy operation. Compared with traditional fluorescent probes, chiral molecules with aggregation-induced emission (AIE) have drawn increasing interests due to their huge potential in high-efficiency chemo/biosensors and solid emitters. Chiral AIE luminogens (AIEgens) can not only discriminate two enantiomers with excellent enantioselectivity, but also show general applicability for many chiral analytes, such as chiral acids, amino acids, amines, alcohols. In this review, we mainly summarized the recent development of chiral probes with AIE properties, including chiral tetraphenylethylene (TPE) derivatives, α-cyanostilbene derivatives, Schiff base derivatives and other AIEgens. Their synthetic routes, recognition capabilities and possible working mechanisms were well discussed. It is envisioned that the present review can give some significant guidance for design and synthesis of chiral AIEgens with good enantioselectivity and inspire more readers to join the research of chiral AIE.
Due to its difficulty and complexity, the cleavage and subsequent functionalization of the C(sp3)-C(sp3) single bond has received less attention than the CC bond formation reactions that have been extensively studied. Herein, by utilizing Cu/g-C3N4 nanometric semiconductor as a recyclable photocatalyst, an aerobic oxidative CC bond cleavage of aldehydes was developed with the promotion of amines under visible light irradiation. Based on the reaction, phenylacetaldehyde was selected as a highly efficient formylation reagent for amines. Under blue light irradiation, good to excellent yields of formamides were achieved for various amines in 1 atm oxygen atmosphere at room temperature. This methodology offers a practical, neutral and gentle alternative to the preparation of formamides.
Designing single-atom nanozymes with densely exposed metal atom active sites and enhancing catalytic activity to detect pollutants remain a serious challenge. Herein, we reported a single-atom nanozyme with layered stacked Fe/Cu dual active sites (Fe/Cu-NC SAzyme) synthesized via hydrothermal and high-temperature pyrolysis using folic acid as a template. Compared with Fe-NC and Cu-NC SAzyme, Fe/Cu-NC SAzyme has higher peroxidase-like activity, which indicates that the doping of synthesized Fe/Cu bimetals can improve the catalytic activity and that the atomic loading of Fe and Cu in Fe/Cu-NC is 5.5 wt% and 2.27 wt%, respectively. When S2− is added to the Fe/Cu-NC catalytic system, a high-sensitivity and high-selectivity S2− colorimetric sensing platform can be established, with a wide linear range (0.09–6 µmol/L) and a low detection limit (30 nmol/L), which can be used to detect S2− in environmental water samples. What's more, the Fe/Cu-NC SAzyme can activate peroxymonosulfate (PMS) to degrade 99.9% of rhodamine B (RhB) within 10 min with a degradation kinetics of 0.5943 min−1. This work details attractive applications in Fe/Cu-NC SAzyme colorimetric sensing and dye degradation.
The lantern-shaped cage Pd2L4 and tweezer-like PdL2 can be synthesized from the trans- and cis-isomer of an azobenzene-containing ligand, respectively, which were characterized by 1H, 13C, 1H-1H COSY, DOSY NMR spectroscopies, high-resolution ESI-MS and density function theory (DFT) calculations. The interconversion of Pd2L4 and PdL2 can be achieved via the cis-trans isomerization of the azobenzene unit on the ligand upon alternative irradiation of light 365 nm or 420 nm.
Levofloxacin (LVFX) as a representative drug of quinolone antibiotics is widely used in clinical, and its residues enriched in water bodies and sideline products seriously damage human health. It is imperative to develop a real-time/on-site sensing method for monitoring residual antibiotics. Here, we report a portable sensing platform by utilizing a composite fluorescent nanoprobe constructed by the cerium ions (Ce3+) coordination functionalized CdTe quantum dots (QDs) for the visual and quantitative detection of LVFX residues. This fluorescent probe provides a distinct color variation from red to green, which shows a good linear relationship to LVFX residues concentrations in the range of 0-6.0 µmol/L with a sensitive limit of detection (LOD) of 16.3 nmol/L. The smartphone platform with Color Analyzer App installed, which could accomplish quantified detection of LVFX in water, milk, and raw pork with a LOD of 27.9 nmol/L. The facile sensing method we proposed realizes rapid visualization of antibiotics residual in the environment and provides a practical application pathway in food safety and human health.
Realizing both a high emission efficiency and luminescence dissymmetry factor (glum) in circularly polarized solution processable organic light-emitting diodes (CP-OLEDs) remains a significant challenge. In this contribution, two chiral phosphorescent liquid crystals based on cyclometalated platinum complexes are prepared, in which the chiral s-2-methyl-1-butyl group is introduced into the cyclometalating ligand and the mesogenic fragment is attached to the periphery of the ancillary ligand. The platinum complexes exhibit both smectic and chiral nematic phases as evidenced by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray diffraction. Remarkably, a high photoluminescent quantum efficiency of over 78% and clear circularly polarized luminescent signal with gPL of about 10–2 are observed for the complexes. Further, solution-processed CP-OLEDs show maximum external quantum efficiencies (EQE) of over 15% and strong circularly polarized electroluminescent signals with a gEL ≈ 10–2. This research demonstrates that both liquid crystallinity and the number of chiral centers play key roles in improving the chiroptical property, paving the way for a new approach for the design of high-efficiency CPL emitters.
Extracellular vesicles (EVs) are cell-derived nanosized vesicles widely recognized for their critical roles in various pathophysiological processes. Molecular analysis of EVs is currently being considered an emerging tool for diseases diagnosis. However, the small size and heterogeneity of EVs has staggered the EVs research for diseases diagnosis. DNA nanotechnology enables self-assembly of versatile DNA nanostructures and has shown enormous potential in assisting EVs biosensing. In this review, we briefly introduce the recent advances in DNA nanotechnology approaches for EVs detection. The approaches were categorized based on the dimension of DNA nanostructures. We provide critical evaluation of these approaches, and summarize the pros and cons of specific methods. Further, we discuss the challenges and future perspectives in this field.