Latest ArticlesWaste polyolefin plastics, accounting for 50% of all plastic waste, represent a tremendously unexploited carbon source. Efficiently upcycling polyolefin waste into value-added carbon materials for waste water treatment avoiding using noble metals is challenging but economically and environmentally sustainable. In this work, MAX-Ti3AlC2 supported Fe selectively catalyzes polyolefin into few-layered graphene in 5 min under microwave treatment. Graphene and MAX supported Fe (Fe@MLC) can completely (99.9%) degrade chloramphenicol (CAP) within 60 min, retain robust after 10 cycles and work efficiently at a wide pH range (3.87–13.03), avoiding the usage of noble metal. Moreover, the electrochemical active surface area (ECSA) of Fe@MLC is 2.7 times higher than that of commercial Pt/C. This work provides a cheap and efficient catalyst that promotes deconstruction of plastic wastes and indirectly degrades antibiotics thereby realizes the treatment of waste water with waste plastic.
In the physiological environment, nanoparticles (NPs) interact with proteins to form a protein-rich layer on the surface which is called "protein corona". Understanding and analyzing the formation process of protein corona and protein corona-nanoparticles is of great significance for biological related nano research. Many separation techniques have been used to analyze the composition of protein corona, but in situ analysis of protein corona is still absent. With the development of detection technology, sum frequency generation (SFG) is an effective instrument to analyze the surface protein structure and dynamic changes of protein corona in situ. In this work the molecular mechanism and surface structure effect of the interaction between nanoparticles with surface protein corona (S-NPP) and phospholipid membrane were studied. When S-NPP interacts with phospholipid membrane, the bond affinity network formed by the binding water can stabilize S-NPP around the lipid bilayer. In this process, S-NPP can be found wrapped in the hydration shell. This ultimately leads to a more moderate interaction between particles and phospholipid membrane.
The electric field-induced irreversible domain wall motion results in a ferroelectric (FE) hysteresis. In antiferroelectrics (AFEs), the irreversible phase transition is the main reason for the hysteresis effects, which plays an important role in energy storage performance. Compared to the well-demonstrated FE hysteresis, the structural mechanism of the hysteresis in AFE is not well understood. In this work, the underlying correlation between structure and the hysteresis effect is unveiled in Pb(Zr, Sn, Ti)O3 AFE system by using in-situ electrical biasing synchrotron X-ray diffraction. It is found that the AFE with a canting dipole configuration, which shows a continuous polarization rotation under the electric field, tends to have a small hysteresis effect. It presents a negligible phase transition, a small axis ratio, and electric field-induced lattice changing, small domain switching. All these features together lead to a slim hysteresis loop and a high energy storage efficiency. These results offer a deep insight into the structure-hysteresis relationship of AFEs and are helpful for the design of energy storage material.
MOF-based core-shell structures with high surface area, abundant active sites, and broad absorption bands are viable alternatives to traditional single-component photocatalysts. In this report, we describe the design and construction of delicate Ag nanowires@NH2-UiO-66 with a core-shell structure for use as photocatalysts in imine synthesis under light. The optimized composites exhibited 80% imine production, which was higher than both MOF and Ag NWs. The significant improvement in photocatalytic activity under light may be attributed to the plasmonic effect of silver nanowires and their core-shell structure, which promotes the separation of electron-hole pairs. Moreover, the photocatalytic activity of the core-shell nanostructure may provide valuable insight into the design and construction of MOF-based composite photocatalysts for oxidative coupling of amines.
Melanoma is one of the most malignant skin tumors, whose high invasion is generally associated with BRAF gene mutation. Although new chemotherapeutic drugs, such as vemurafenib, have been developed to inhibit the growth of melanoma, these drugs are usually administered intravenously or orally, resulting in toxic side effects on major tissues and organs. Tetrahedral framework nucleic acids (tFNAs) are a novel type of DNA nanostructures with excellent biocompatibility and versatility which have been proven to penetrate through skin barrier with ease. In this study, we prepared tFNAs with vemurafenib and connected DNA aptamer AS1411 at the apex of tFNAs (AS1411-tFNAs/vemurafenib). On one hand, AS1411-tFNAs/vemurafenib could kill melanoma cells by blocking the mutated BRAF gene in vitro. Compared with free vemurafenib, AS1411-tFNAs/vemurafenib had no obvious toxicity to normal cells. On the other hand, AS1411-tFNAs could transfer vemurafenib to cross through the skin barrier and permeate into tumor tissues. In vivo, transdermal delivery of AS1411-tFNAs/vemurafenib could inhibit the growth of human A375 melanoma, whose inhibiting effect was stronger than intravenous administration of vemurafenib. These results demonstrated the application prospects of tFNAs combined with chemotherapeutic drugs in skin tumors.
The blue-light-excitable phosphors play a crucial role in the high-performance white LEDs. Here, we report on two new Cu(Ⅰ) coordination network materials as yellow-emitting phosphors prepared by suitably expanded π-conjugated triazole ligands. Upon blue-light irradiation, these complexes exhibit efficient solid-state emission and enhanced photostability. Through incorporating the yellow phosphor and a commercial blue-green powder (BaSi2N2O2:Eu2+) with a blue LED chip, the phosphor-converted LED devices display remarkable white emission properties. The experimental results demonstrate that the Cu(Ⅰ) coordination network materials function as promising blue-light excitable phosphors with great application potential for full-spectrum white LEDs.
Developing accurate and sensitive DNA methyltransferase (MTase) analysis methods is essential for early clinical diagnosis and development of antimicrobial drug targets. In this work, by coupling WO3−x dots-encapsulated metal-organic frameworks (MOFs) as co-reactants and terminal deoxynucleotidyl transferase (TdT)-mediated template-free branched polymerization, a dual signal-amplified electrochemiluminescent (ECL) biosensor was constructed to detect DNA adenine methylation (Dam) MTase. The employment of WO3−x dots-encapsulated MOFs (i.e., NH2-UIO66@WO3−x) was not only beneficial for biomolecule conjugation because of the abundant amino groups but also led to a 7-fold enhanced ECL response due to the increased loading of WO3−x. Moreover, TdT-mediated template-free branched polymerization promoted the capture of ECL emitters on the electrode surface, achieving 20-fold enhanced signal amplification. The presented ECL biosensor demonstrated a low detection limit of 2.4 × 10−4 U/mL, and displayed high reliability for the detection of Dam MTase in both spiked human serum and E. coli cell samples, and for the screening of potential inhibitors. This study opens a new avenue for designing a dual signal amplification-based ECL bioassay for Dam MTase and screening inhibitors in the fields of clinical diagnosis and drug development.
Unspecific peroxygenases (UPOs, EC 1.11.2.1) is a kind of thioheme enzyme capable of catalyzing various oxidations of inert C–H bonds using H2O2 as an oxygen donor without cofactors. However, the enhancement of the H2O2 tolerance of UPOs is always challenging. In this study, the A161C mutant of rDcaUPO, which originates from Daldinia caldariorum, was found to be highly H2O2-resistant. Compared with the wild type, the mutant rDcaUPO-A161C showed a 10-h prolonged half-life and a 64% improved enzyme activity when incubated in 10 mmol/L H2O2. The crystal structure analysis at 1.47 Å showed that rDcaUPO-A161C exhibited 10 α-helixes (cyan) and a series of ordered rings, forming a single asymmetric spherical structure. The two conserved domains near heme formed an active site with the catalytic PCP and EHD regions (Glu86, His87, Asp88 residues). The H2O2 tolerance of rDcaUPO-A161C was preliminarily explored by comparing its structure with the wild type. Notably, rDcaUPO-A161C showed significantly higher catalytic efficiency than the wild type for the production of hydroxyl fatty acids. This study is anticipated to provide an insight into the structure-function relationship and expand potential applications of UPOs.
Spermatogenesis, maturation, capacitation and fertilization are precisely regulated by glycosylation. However, the relationship between altered glycosylation patterns and the onset and development of reproductive disorders is unclear, mainly limited by the lack of in situ imaging techniques for spermatozoa glycosylation. We developed an efficient and highly specific spermatozoa glycan imaging technique based on the robust chemoselective labeling of sialic acid (Sia) and N-acetyl-d-galactosamine (Gal/GalNAc). We further proposed a "tandem glycan chemoselective labeling" strategy to achieve simultaneous imaging of two types of glycans on spermatozoa. We applied the developed method to the spermatozoa from oligozoospermic patients and diabetic mice and found that these spermatozoa showed higher levels of Sia and Gal/GalNAc expression than the normal groups. Moreover, spermatozoa from diabetic mice showed a severe decrease in number, viability, and forward motility, suggesting that in vivo glucose metabolism disorders may lead to an elevated level of spermatozoa glycosylation and have a correlation with the development of oligoasthenotspermia. Our work provides a research tool to reveal the relationship between glycosylation modification and spermatozoa quality, and a promising clue for the development of glycan-based reproductive markers.
Oxaliplatin (Oxa) is the first-line chemotherapeutic drug for the treatment of colorectal cancer (CRC). However, long-term Oxa chemotherapy can induce inflammation and increase the levels of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2), which can promote tumor metastasis. Moreover, high glutathione (GSH) levels in CRC cells significantly reduce Oxa sensitivity and seriously restrict the clinical application of Oxa. Herein, an Oxa(Ⅳ) prodrug with anti-inflammatory properties (desmethyl naproxe, DN) and GSH-depleting cyclodextrin pseudo-polyrotaxane carriers were prepared and further self-assembled into micellar nanoparticles (designated DNPt@PPRI). The relesae of DN from DNPt@PPRI can reduce the level of PGE2 to inhibit inflammation and tumor metastasis by decreasing COX-2 protein, and also synergize with Oxa to inhibit tumor. More importantly, GSH depletion can reduce the detoxification of Oxa and further enhance chemotherapy-induced apoptosis. DNPt@PPRI have a good GSH depletion ability to enhance the sensitivity of Oxa, indicating a potential in the synergistic chemotherapy and chemo-sensitization of colorectal cancer.
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