Latest ArticlesAmyloid beta-peptide 1–42 (Aβ1–42) is one of the biomarkers of Alzheimer's disease, and its selective capture and quantitative detection are important for diagnosis and treatment of Alzheimer's disease. Herein, copper(Ⅱ) ions-immobilized virus-like hollow covalent organic frameworks (V-HCOFs@Cu2+) were synthesized by a facile approach. The as-prepared V-HCOFs@Cu2+ showed unique morphology, ultra-high specific surface (2552 m2/g), uniform mesoporous structure (3.2 nm), superior chemical stability and abundant binding sites. Based on these excellent properties, the V-HCOFs@Cu2+ could be adopted as an ideal enrichment probe for highly efficient capture of Aβ1–42, exhibiting high adsorption capacity (320 mg/g), and fast adsorption equilibration time (3 min). In addition, an attractive approach of the V-HCOFs@Cu2+-based matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was developed for the rapid screening and quantitative analysis of Aβ1–42 in human serum by using C-peptide as an internal standard, which exhibited low limit of detection (LOD, 0.2 fmol/µL), and satisfactory recovery. This work provides an alternative solution for enrichment of biomarkers and also offers the potential applications of COFs in clinical analysis
Ni(0)-catalyzed regio- and diastereodivergent [4 + 2] annulation of biphenylenes with α, β unsaturated ketones is described. This solvent-controlled diastereodivergent reaction integrates C-C bond cleavage of biphenylene and C=C double bond insertion selectivity, offering a mild approach to all possible diastereoisomers of 9, 10-dihydrophenanthrene derivatives from the same starting materials.
Stimuli-responsive vesicles (SRVs) have been widely exploited as smart nanocarriers for biomedical applications. Herein, high-performance SO2-responsive nanovesicles were reported to exemplify a new mode of SRVs. Structurally, the sensory vesicles were based on amphiphilic hydrogen-bonded (HB) polymers which can be facilely fabricated via modular self-assembly. The HB polymers are designed to consist of a melamine-barbituric acid HB skeleton with pendant anthracene fluorophores and amphiphilic side chains. Upon stimulation with increasing amount of SO2, the vesicles in aqueous solution undergo an unusual morphology evolution including rapid fission into small ones, swelling and final collapse of the offspring vesicles. During this process, the intrinsic fluorescence response of the vesicles allows intuitive tracking of the hierarchical structural evolution of the self-assembled membranes and straightforward quantitation of the stimuli. This work exemplifies a rational design of auto-recording stimuli-responsive nanovesicles.
Treatment of antibiotics contaminated water remains a global environmental challenge. In this study, tetracycline (TC) was found to effectively sensitize pure TiO2 for visible light photocatalytic degradation via a ligand-to-metal charge transfer mechanism. The sensitization was attributed to the formation of TC-TiO2 complex and the overlap of the molecular orbitals of TC and the conduction band of TiO2. The intermediate degradation products of TC, however, did not sensitize TiO2, which was the reason for the low mineralization rate. Nevertheless, our results showed that the intermediate degradation products of TC had significantly reduced bactericidal effects and less induction of antibiotic-resistance genes (ARGs). This study showcases an effective treatment of antibiotics-containing wastewater using the most common photocatalyst TiO2 with reduced risk in the spread of ARGs.
A calix[4]arene ligand assisted direct β-C−H arylation of tertiary aliphatic aldehydes has been developed via a Pd-catalyzed C(sp3)−H functionalization process. This strategy exhibited good functional group compatibility and C−H bond site-selectivity. Mechanism studies have shown that both synergistic effect and cationic-π supramolecular interaction between calixarene cavity and transition-metal catalytic center may play an important role in this catalytic cycle. This complementary method would be used in organic and medical chemistry due to the importance of tertiary aliphatic aldehydes.
Diabetic wounds lead to a decrease in quality of life and an increase in mortality. Current treatment strategies include preventing bacterial adhesion while improving microcirculation. As a new type of wound dressing that imitates natural skin, hydrogel has gradually emerged with its excellent properties. However, existing hydrogels rarely achieve satisfactory results in promoting wound repair and antibacterial simultaneously. In this case, we prepared methacrylic anhydride chemically modified hyaluronic acid as a hydrogel matrix, added polyhexamethylene biguanide as an antibacterial component, and loaded sodium alginate/salidroside composite microspheres which could sustainably release salidroside and thus promote angiogenesis. Hybrid hydrogel (HAMA/PHMB-Ms) was synthesized via photocrosslinking, and its chemical structure, particle size distribution and microstructure were characterized. The satisfactory antibacterial properties of the HAMA/PHMB(15%)-Ms hydrogel were studied in vitro, and its antibacterial rates against E. coli and S. aureus were 97.85% and 98.56%, respectively. In addition, after demonstrating its good biocompatibility, we verified that the HAMA/PHMB-Ms hydrogel has increased granulation tissue formation, more collagen deposition, more subcutaneous capillary formation, and better wound healing than blank control, HAMA and HAMA/PHMB hydrogel on the back wound model of diabetic mice. The results confirmed that HAMA/PHMB-Ms hydrogel was a promising material for the treatment of the diabetic wounds.
A stimuli-responsive supramolecular polymer network has been constructed based on the host-guest interactions between the copolymer poly-P[5]A with pendent pillararene units and bis(sulfonium) diction guest G2. The formation mechanism of the supramolecular polymer network has been explored by the intensive study. With the addition of the competitive molecules and heating, the supramolecular polymer network could be dissociated and lead to clear changes in NMR spectroscopy and viscosity property.
Homogeneous gold catalysis has demonstrated the preponderant capability of realizing a broad range of synthetically versatile alkyne functionalization over the last two decades. Though catalytic asymmetric alkyne transformation has focused on the principle of using gold catalysts either associated with chiral phosphine ligand or combined with chiral counterion, a variety of breakthroughs have been reported with the application of gold-complex and chiral organocatalyst cooperative catalysis strategy, which could enable the challenging transformations that cannot be realized by mono-catalysis with excellent stereoselectivity. This review will cover two general protocols in this field, including relay catalysis and synergistic catalysis, with emphasis on the detailed cooperative catalysts models to illustrate the roles of the two catalysts and highlight the potential synthetic opportunities offered by asymmetric cooperative catalysis.
The need for temporal resolution and long-term stability in super-resolution fluorescence imaging has motivated research to improve the photostability of fluorescent probes. Due to the inevitable photobleaching of fluorophores, it is difficult to obtain long-term super-resolution imaging regardless of the self-healing strategy of introducing peroxide scavengers or the strategy of fluorophore structure modification to suppress TICT formation. The buffered fluorogenic probe uses the intact probes in the buffer pool to continuously replace the photobleached ones in the target, which greatly improves the photostability and enables stable dynamic super-resolution imaging for a long time. But the buffering capacity comes at the expense of reducing the number of fluorescent probes in targets, resulting in low staining fluorescence intensity. In this paper, we selected BODIPY 493, a lipid droplet probe with high fluorescence brightness, to explore the dynamic process of lipid droplet staining of this probe in cells. We found that BODIPY 493 only needs very low laser power for lipid droplet imaging due to the high molecular accumulation in lipid droplets and the high brightness, and the spatiotemporal resolution is greatly improved. More importantly, we found that BODIPY 493 also has a certain buffering capacity, which enables BODIPY 493 to be used for super-resolution imaging of lipid droplet dynamics. This work reminds researchers to coordinate the buffering capacity and brightness of fluorogenic probes.
Highly enantioselective Rh-catalyzed partial hydrogenation of unprotected simple 2-alkyl-5-aryl-disubstituted pyrroles has been successfully developed, generating a series of chiral 1-pyrroline derivatives generally with excellent results (95%–99% yields, 91%–96% ee). Moreover, 2,5-aryl-1H-pyrroles were hydrogenated well in high yields and good enantioselectivities. This efficient protocol features easily accessible substrates, wide substrate scope, well functional group compatibility, commercially available rhodium precursor and chiral ligand. It provides a versatile route to access chiral 1-pyrroline derivatives that are of great importance in organic synthesis and pharmaceutical chemistry.
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