Latest ArticlesBoth nitrogen-doping feature and pore structure are critical factors for developing nitrogen-doped carbons based catalysts with a high performance toward oxygen reduction reaction (ORR). Herein, a simple one-step CVD of acetylene and acetonitrile vapor method using silanized SBA-15 as a template has been developed to synthesize an ordered porous carbon (OPC) with dual nitrogen-doped interfaces. The optimized sample as prepared with the CVD of 4 h at 750 ℃ contains two types of ordered mesopores that one type is the ordered cylindrical pores inheriting from the pores of SBA-15 and has a pore width of 4.0~5.0 nm, the other type is the ordered quasi-hexagonal pores with a width of 3.0~4.0 nm produced by etching the pore walls of SBA-15. These two types of pores whose pore walls are built by the nitrogen doped carbon layers resulted by the CVD and thus it actually makes the dual nitrogen-doped interfaced OPC (DN-OPC). Meanwhile, DN-OPC contains a few of micropores and a large SSA of 1430 m2/g. This dual-ordered pores and dual nitrogen-doped interfaces cannot only facilitate mass transport but also utilize the active sites of DN-OPC for ORR. Therefore, as metal-free ORR catalyst, DN-OPC exhibits a good activity close to commercial Pt/C catalyst, and an excellent durability and methanol tolerance.
3D highly ordered silver nanoparticles (AgNPs) coated silica photonic crystal beads (Ag/SPCBs) were prepared and exploited as a novel surface enhanced Raman scattering (SERS) substrate. The monodisperse and size-controlled SPCBs were prepared via self-assembly of silica nanoparticles process using a simple microfluidic device. Then the Ag/SPCBs were easily obtained by in situ growth of AgNPs onto the NH2-modified SPCBs. Field emitting scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX) were used to characterize the Ag/SPCBs. The effect of silica nanoparticle size and AgNO3 concentration on the SERS performance of the resultant Ag/SPCBs substrate were discussed in detail. The results indicate that the Ag/SPCBs have highest SERS signals when silica nanoparticle size is 250 nm and AgNO3 concentration is 0.8 mg/mL. Using malachite green (MG) as model analyte, the Ag/SPCBs substrate displayed a high sensitivity and a wide linear range for MG. The well-designed Ag/SPCBs show high uniformity and excellent reproducibility, and can be used as an effective SERS substrate for sensitive assay application.
Fe3O4 is considered as a promising electrode material for lithium-ion batteries (LIBs) due to its low cost and high theoretical capacity (928 mAh/g). Nevertheless, the huge volume expansion and poor conductivity seriously hamper its practical applications. In this study, we use a facile hydrothermal reaction together with a post heat treatment to construct the three-dimensional heterostructured composite (Fe3O4/rGO) inwhich reduced graphene oxide sheets wraped the Fe3O4 submicron cubes as the conductive network. The electric conduction and electrode kinetics of lithium ion insertion/ extraction reaction of the composite is enhanced due to the assist of conductive rGO, and thus the Li-storage performance is obviously improved. The composite exhibits a reversible charge capacity of 772.1 mAh/g at the current density of 0.1 A/g, and the capacity retention reaches 70.3% after 400 cycles at 0.5 A/g, demonstrating obviously higher specific capacity and rate capability over the Fe3O4 submicron cubes without rGO, and much superior cycling stability to the parent Fe2O3 submicron cubes without rGO. On the other hand, as a synergic conductive carbon support, the flexible rGO plays an important role in buffering the large volume change during the repeated discharge/charge cycling.
The designed synthesis of chiral covalent organic frameworks (COFs) featuring intriguing properties is fairly scant and remains a daunting synthetic challenge. Here we develop a de novo synthesis of an enantiomeric pair of 2D hydroxyl-functionalized hydrazone-linked chiral COFs, (S)- and (R)-HthBta-OH COFs, using enantiopure 2, 5-bis(2-hydroxypropoxy)terephthalohydrazide (Hth) as monomers. The formation process of hydroxyl-functionalized chiral COFs was monitored using rigorous time-dependent PXRD, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) studies. Remarkably, VCD spectra indicated a unique chiral signal inversion from the positive Cotton effect of (S)-Hth monomer to the negative Cotton effect of (S)-HthBta-OH COF, which has never been reported in chiral COFs. Moreover, two unprecedented carboxyl-functionalized chiral COFs, (S)- and (R)-HthBta-COOH, were constructed by a post-synthetic modification of the corresponding hydroxyl chiral COFs with succinic anhydride. Notably, carboxyl-functionalized COFs retained homochirality and crystallinity without linker racemization and structural collapse after the chemical modification due to the chemically robust nature of pristine hydrazone-linked chiral COFs.
Carbon nitride (CN) photocatalysts have attracted much attention due to their excellent photocatalytic properties. And hydrothermal fluorination is a common method to improve the photocatalytic effect of CN photocatalyst. Here, the influence of the band gap was first revealed of fluorination and hydroxylation of CN photocatalyst based on the first theoretical principle. Here, the effect of fluorination and hydroxylation on the CN band gap was discussed for the first time using the first theoretical principle. With F atoms and OH doping, the band gap of CN was significantly improved, conduction band and valence band moved up. Then, F—CN photocatalyst with F atoms and OH was successfully synthesized by a hydrothermal fluorinated method. Next, the reasons why F—CN photocatalyst was more effective than that of traditional CN photocatalyst were fully discussed. From the photocatalytic effect of photocatalyst (12, 593.2 μmol g-1 h-1 to the morphology (super-small nanosheets), structure (homojunctions), composition (metal-free), specific surface area (54.1 m2/g), visible light absorption response (AQE is 10.9% at 420 nm) and photo-induced carrier life (14.13 ns). Therefore, this work has a great guiding effect on the development of CN photocatalyst.
Five novel biscembranoids, ximaolides H–L (1–5), along with four known related compounds (6–9) were isolated from the Hainan soft coral Sarcophyton tortuosum. The structures of the new compounds were determined by extensive spectroscopic analysis, quantum chemical calculations, and/or by comparing their CD spectra with those of the known compounds. Compounds 1 and 2 are the first examples of biscembranoids bearing a 1,35-bridged lactone moiety, 4 is the first biscembranoid comprising an uncommon oxetane ring, and 5 represents the first 36-peroxyl biscembranoid. Ximaolides I (2), K (4) and F (9) exhibited interesting anti-inflammatory activity by the inhibition of LPS-induced TNF-α protein release in RAW264.7 macrophages.
Corneal neovascularization (CNV) can induce severe visual impairment and even blindness. Current treatments have limited efficacy and some undesirable side effects. Phototherapy (PT) is a modern medical technique in CNV treatment and worth further improvement. Nanotechnology has various advantages and nanoparticle-mediated drug delivery also contributes to CNV elimination. Phototherapy combined with functional nanoparticles featuring photoacoustic imaging contrast properties can accomplish accurate and safe inhibition of CNV, thus is promising in clinical application.
Despite the promising prospect of small interfering RNA (siRNA) for the treatment of diverse diseases, it remains challenging to develop novel delivery materials to desired tissues and cells. In this study, a novel iron oxyhydroxide (FeOOH) nanoparticle (NP) whose surface was modified with branched polyether-imide (PEI) was developed to deliver siRNA into the cancer cells. It was demonstrated that PEI-FeOOH (PFeOOH) efficiently complexed siRNA, mediated effective cellular uptake and endosomal escape, thereby triggering robust gene silencing in vitro. In addition, PFeOOH/siRNA formulation loading with anti-RRM2 siRNA effectively inhibited the growth of tumor tissues, and exhibited excellent safety profiles in vivo. Therefore, this study conceptually provided a FeOOH-based nucleic acid delivery vesicle which can potentially use to achieve diagnosis and therapy simultaneously.
Atherosclerosis is a persistent inflammatory state, while vascular endothelial fibrosis is one of the primary causes of atherosclerosis development. Although ligustilide (Lig) was shown to exert obvious antiatherogenic effects in previous studies, its precise mechanism has not been deeply discussed. In this paper, we designed a Lig-derived photoaffinity labelling (PAL) probe to identify potential therapeutic targets of Lig via chemical proteomics approach. Mothers against decapentaplegic homologue 3 (SMAD3), a signal transmitter of transforming growth factor-β (TGF-β) which promotes the development of vascular fibrosis, was identified as a potential target of Lig. Lig suppressed the phosphorylation and nuclear translocation of SMAD3 by blocking the interaction between SMAD3 and TGF-β receptor 1, thereby inhibiting the collagen synthesis process. Hence, developing a novel SMAD3 inhibitor may present a promising therapeutic option for preventing vascular fibrosis.
Aptamer is an oligonucleotide chain with specific binding ability to protein and other targets, which is widely used in many fields. Because of its ability to screen the premise of unknown targets, it can be used to discover some novel tumor markers, i.e., membrane proteins that are specifically highly expressed on the surface of tumor cells. Tumor markers can be used in many fields such as early diagnosis and treatment, and a new type of tumor marker proved to be effective can significantly improve the therapeutic effect of such tumors. However, further characterization of newly acquired membrane proteins is essential for their clinical use as tumor markers. This review first briefly introduced the process of obtaining novel tumor markers from nucleic acid aptamers. Next, the commonly used protein characterization methods could be used as a technical means to identify membrane protein targets corresponding to tumor cell aptamers, to clarify the principles, advantages and disadvantages of various means, and to analyze the most suitable situations for various experimental methods. Finally, the outlook was made and the characterization methods that should be used in such experiments were summarized.
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