An electrostatic self-assembly approach was employed to prepare Fe3O4/graphene oxide nanocomposites, and their application in the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons ...from environmental samples was investigated. With the highly hydrophilic graphene oxide sheets and positively charged surface of the Fe3O4 nanoparticles, the nanocomposites were synthesized through electrostatic interaction in aqueous solution. Simultaneously, the different loading amounts of Fe3O4 onto the graphene oxide were easily controlled by changing the proportion of the initial precursors. The identity of the hybrid materials was confirmed using transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and a vibrating sample magnetometer. Five polycyclic aromatic hydrocarbons were selected as model analytes to validate the extraction performance of the Fe3O4/GO nanocomposite as a MSPE sorbent. The excellent adsorption property was attributed to the dominant roles of π–π stacking interaction and hydrophobic interaction. After optimizing the conditions, the results indicated that the recoveries of these compounds were in the range of 76.8–103.2%, with relative standard deviations ranging between 1.7% and 11.7%; the limits of detection were in the range of 0.09–0.19ngmL−1.
► Prepare Fe3O4/graphene oxide nanocomposites through electrostatic self-assembly. ► The different loading amounts of Fe3O4 on graphene oxide was easily controlled. ► Fe3O4/GO nanocomposites showed excellent performance for the extraction of PAHs.
Microtissues with specific structures and integrated vessels play a key role in maintaining organ functions. To recapitulate the in vivo environment for tissue engineering and organ-on-a-chip ...purposes, it is essential to develop perfusable biomimetic microscaffolds. We developed facile all-aqueous microfluidic approaches for producing perfusable hydrogel microtubes with diverse biomimetic sizes and shapes. Here, we provide a detailed protocol describing the construction of the microtube spinning platforms, the assembly of microfluidic devices, and the fabrication and characterization of various perfusable hydrogel microtubes. The hydrogel microtubes can be continuously generated from microfluidic devices due to the crosslinking of alginate by calcium in the coaxial flows and collecting bath. Owing to the mild all-aqueous spinning process, cells can be loaded into the alginate prepolymer for microtube spinning, which enables the direct production of cell-laden hydrogel microtubes. By manipulating the fluid dynamics at the microscale, the composable microfluidic devices and platforms can be used for the facile generation of six types of biomimetic perfusable microtubes. The microfluidic platforms and devices can be set up within 3 h from commonly available and inexpensive materials. After 10-20 min required to adjust the platform and fluids, perfusable hydrogel microtubes can be generated continuously. We describe how to characterize the microtubes using scanning electron or confocal microscopy. As an example application, we describe how the microtubes can be used for the preparation of a vascular lumen and how to perform barrier permeability tests of the vascular lumen.
•HPLC stationary phases bonded with graphene oxide and graphene were prepared.•Graphene was firstly applied as stationary-phase component for HPLC.•Effective HPLC separations were achieved on GO@SiO2 ...and G@SiO2 columns.•A mixed-mode retention mechanism of the novel stationary phases was proposed.•Analytes of similar hydrophobicity were separated easily on GO@SiO2 column.
Graphene oxide (GO) bonded stationary phase for high performance liquid chromatography (HPLC) was fabricated by coating GO sheets onto aminosilica microspheres via covalent coupling. Graphene (G) functionalized HPLC stationary phase was then prepared through hydrazine reduction of GO bonded silica (GO@SiO2) composite, which was the first example of using graphene as stationary-phase component for HPLC. Effective separations of the tested neutral and polar compounds on both GO@SiO2 and graphene bonded silica (G@SiO2) columns were achieved under the optimal experimental conditions. Compared with commercial C18 column, the different chromatographic performances of GO and graphene bonded columns were ascribed to their unique retention mechanisms. The polyaromatic scaffold of GO and graphene gives π–π stacking property and hydrophobic effect, and other retention mechanisms, such as π–π electron-donor–acceptor (EDA) interaction for the separation of nitroaromatic compounds and hydrogen bonding for hydroxyl and amino compounds, may also be taken into consideration. Experimental results indicated that the mixed-mode retention mechanism can facilitate the separation of analytes with similar hydrophobicity, which is a unique property compared with C18 column. Additionally, G@SiO2 showed higher affinity to aromatic analytes in contrast with GO@SiO2 and its retention mechanism was not consistent with the typical reversed phase behavior. The separation of aromatic compounds on G@SiO2 column relies primarily on the π–π stacking interaction and then the hydrophobicity, while the two interactions have equal shares on GO@SiO2 column.
Oxidative stress is associated with many acute and chronic inflammatory diseases. Development of nanomaterial-based enzyme mimetics for reactive oxygen species (ROS) scavenging is challenging, but ...holds great promise for the treatment of inflammatory diseases. Herein, we report the highly ordered manganese dioxide encapsulated selenium-melanin (Se@Me@MnO
2
) nanozyme with high efficiency for intracellular antioxidation and anti-inflammation. The Se@Me@MnO
2
nanozyme is sequentially fabricated through the radical polymerization and the
in-situ
oxidation-reduction.
In vitro
experimental results demonstrated that the Se@Me@MnO
2
nanozyme exhibits multiple enzyme activities to scavenge ROS, including catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). Mechanism researches illustrated that the Se core possesses GPx-like catalytic activity, the Me and the MnO
2
possess both the SOD-like and the CAT-like activities. What’s more, due to the stable unpaired electrons existing in the nanozyme, the Se, Me and MnO
2
provide synergistic and fast electron transfer effect to achieve the quickly scavenging of hydrogen peroxide, hydroxyl radical, and superoxide anion. Further
in vivo
experimental results showed that this biocompatible nanozyme exhibits cytoprotective effects by resisting ROS-mediated damage, thereby alleviating the inflammation. This multienzyme mimetics is believed to be an excellent ROS scavenger and have a good potential in clinical therapy for ROS-related diseases.
Selective separation of heme proteins and peptides from complicated biological samples before comprehensive identification and characterization of intact biomolecules which are low stoichiometry is ...indispensable for ongoing proteomics. Here, three magnetic mesoporous rare-earth silicate (rare-earth = Er, Tm, Yb) microspheres prepared by facile solvothermal method were used as novel adsorbents for the selective isolation of bovine hemoglobin (BHb), and magnetic mesoporous ytterbium silicate showed apparent adsorption efficiency in isolating BHb with a adsorption capacity of 304.4 mg/g after the comparison. The retained BHb could be eluted by using Na2CO3 as stripping reagent. Meanwhile, Circular dichroism spectra illustrated that the microspheres posed no effect on the secondary structure of BHb. The resultant magnetic particles were characterized by transmission electron microscope, scanning electron microscope, x-ray powder diffraction, vibrating sample magnetometer, Fourier transform infrared spectroscopy, N2 adsorption−desorption isotherm and zeta potential. The as-prepared magnetic microspheres showed high specificity for the separation of BHb from bovine plasma as corroborated by SDS-PAGE and MALDI-TOF MS analysis, which would be expected to possess potential application in isolation of other heme proteins in complex biological samples.
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•Magnetic rare-earth silicate (rare-earth = Er, Tm, Yb) microspheres were synthetized.•Magnetic ytterbium silicate showed better BHb enrichment effect after comparison.•The novel method was successfully applied to isolate BHb from bovine serum.
Deoxynivalenol (DON) is the most frequently detected mycotoxin in cereal grains and processed food or feed. Two transcription factors, Tri6 and Tri10, are essential for DON biosynthesis in Fusarium ...graminearum. In this study we conduct stranded RNA-seq analysis with tri6 and tri10 mutants and show that Tri10 acts as a master regulator controlling the expression of sense and antisense transcripts of TRI6 and over 450 genes with diverse functions. TRI6 is more specific for regulating TRI genes although it negatively regulates TRI10. Two other TRI genes, including TRI5 that encodes a key enzyme for DON biosynthesis, also have antisense transcripts. Both Tri6 and Tri10 are essential for TRI5 expression and for suppression of antisense-TRI5. Furthermore, we identify a long non-coding RNA (named RNA5P) that is transcribed from the TRI5 promoter region and is also regulated by Tri6 and Tri10. Deletion of RNA5P by replacing the promoter region of TRI5 with that of TRI12 increases TRI5 expression and DON biosynthesis, indicating that RNA5P suppresses TRI5 expression. However, ectopic constitutive overexpression of RNA5P has no effect on DON biosynthesis and TRI5 expression. Nevertheless, elevated expression of RNA5P in situ reduces TRI5 expression and DON production. Our results indicate that TRI10 and TRI6 regulate each other's expression, and both are important for suppressing the expression of RNA5P, a long non-coding RNA with cis-acting inhibitory effects on TRI5 expression and DON biosynthesis in F. graminearum.
Molecularly imprinted polymers (MIPs) were applied for selective enrichment of proteins in MALDI-TOF MS analysis for the first time. MIPs were achieved simply via immobilization of template lysozyme ...(Lyz) on core-shell magnetic nanoparticles and self-polymerization of dopamine (DA).
Graphene has great potentials for the use in sample preparation due to its ultra high specific surface area, superior chemical stability, and excellent thermal stability. In our work, a novel ...graphene‐based SPE disk was developed for separation and preconcentration of trace polycyclic aromatic hydrocarbons from environmental water samples. Based on the strong π–π stacking interaction between the analytes and graphene, the analytes extracted by graphene were eluted by cyclohexane and then determined by GC‐MS. Under the optimized conditions, high flow rate (30 mL/min) and sensitivity (0.84–13 ng/L) were achieved. The proposed method was successfully applied to the analysis of real environmental water samples with recoveries ranging from 72.8 to 106.2%. Furthermore, the property of anticlogging and reusability was also improved. This work reveals great potentials of graphene‐based SPE disk in environmental analytical.
Cross-modal image-text retrieval is a fundamental task in bridging vision and language. It faces two main challenges that are typically not well addressed in previous works. 1) Generalizability: ...Existing methods often assume a strong semantic correlation between each text-image pair, which are thus difficult to generalize to real-world scenarios where the weak correlation dominates. 2) Efficiency: Many latest works adopt the single-tower architecture with heavy detectors, which are inefficient during the inference stage because the costly computation needs to be repeated for each text-image pair. In this work, to overcome these two challenges, we propose a two-tower cross-modal contrastive learning (CMCL) framework. Specifically, we first devise a two-tower architecture, which enables a unified feature space for the text and image modalities to be directly compared with each other, alleviating the heavy computation during inference. We further introduce a simple yet effective module named multi-grid split (MGS) to learn fine-grained image features without using detectors. Last but not the least, we deploy a cross-modal contrastive loss on the global image/text features to learn their weak correlation and thus achieve high generalizability. To validate that our CMCL can be readily generalized to real-world scenarios, we construct a large multi-source image-text dataset called weak semantic correlation dataset (WSCD). Extensive experiments show that our CMCL outperforms the state-of-the-arts while being much more efficient.
A novel and uncomplicated synthesis method of Cu
2+
-chelating with carboxyl groups that directly-modified NiFe
2
O
4
magnetic microspheres (NiFe
2
O
4
-PAA-Cu
2+
) was fabricated for selective ...enrichment and separation of bovine hemoglobin (BHb). First, a carboxyl group directly-modified on NiFe
2
O
4
magnetic microspheres was gained through a facile one-pot solvothermal method. Second, Cu
2+
from CuSO
4
was brought into use to react with carboxyl groups under mechanical stirring at room temperature. The resulting magnetic microspheres were characterized by distinct instruments that included transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM) and scanning electron microscope (SEM) to examine the size, morphology, composition and magnetization characterization. The results indicated that the NiFe
2
O
4
-PAA-Cu
2+
microspheres exhibited good saturation magnetization (36.686 emu g
−1
), which can facilitate magnetic separation under the help of an outside magnetic field. Also, good dispersion and high adsorption ability to BHb (783.53mg g
−1
) can be applied to selective enrichment for bovine hemoglobin and used for selective sorption of BHb protein in bovine blood samples.
