Latest ArticlesTwo primitive metal-organic frameworks (MOFs), NiL1 and NiL2, based on Ni8O6-cluster and ditopic pyrazolate linkers, L1 (with rigid alkyne arms) and L2 (with flexible alkyne chains), were prepared. The proton conductivities of these MOFs in pristine form and imidazole-encapsulated forms, Im@NiL1 and Im@NiL2, were measured and compared. Upon introduction of imidazole molecules, the proton conductivity could be increased by 3 to 5 orders of magnitude and reached as high as 1.72 × 10−2 S/cm (at 98% RH and 80 ℃). Also, whether imidazole molecules were introduced or not, Ni8O6-based MOFs with L2 in general gave better proton conductivity than those with L1 signifying that flexible side arms indeed assist proton conduction probably via establishment of efficient proton-conducting channels along with formation of highly ordered domains of water/imidazole molecules within the network cavities. Beyond the active Ni8O6-cluster, tuning flexibility of linker pendants serves as an alternative approach to regulate/modulate the proton conductivity of MOFs.
Concentration gradient and fluid shear stress (FSS) for cell microenvironment were investigated through microfluidic technology. The Darcy–Weisbach equation combined with computational fluid dynamics modeling was exploited to design the microfluidic chip, and the FSS distribution on the cell model with varying micro-channels (triangular, conical, and elliptical). The diffusion with the incompressible laminar flow model by solving the time-dependent diffusion–convection equation was applied to simulate the gradient profiles of concentration in the micro-channels. For the study of single cell in-depth, the FSS was investigated by the usage of polystyrene particles and the concentration diffusion distribution was studied by the usage of different colors of dyes. A successful agreement between model simulations and experimental data was obtained. Finally, based on the established method, the communication between individual cells was envisaged and modeled. The developed method provides valuable insights and allows to continuously improve the design of microfluidic devices for the study of single cell, the occurrence and development of tumors, and therapeutic applications.
Biomass-derived dynamic covalent thermoset has been considered as a promising solution to the high dependence on fossil resources and the difficulty in recyclability after curing of conventional bisphenol A epoxy resins. However, the design and preparation of a dynamic covalent biobased epoxy thermoset with both comparable thermal and mechanical performances to bisphenol A epoxy resins and reprocessibility remains a significant challenge. Herein, based on imine chemistry, a novel Schiff base-containing dynamic covalent epoxy thermoset was facilely fabricated from biobased protocatechualdehyde and synthetic siloxane diamine. Due to the more reactive epoxides in the epoxy monomer than in bisphenol A epoxy oligomer, the thermoset exhibited a high cross-linking density, resulting in high thermal stability and glass transition temperature. The rigid aromatic Schiff base moieties endowed the thermoset with excellent mechanical properties: Thanks to the plasticization of the flexible siloxane, the thermoset displayed high impact strength. Meanwhile, owing to the high segmental mobility, the fast exchange of imine bonds was guaranteed; and the thermoset was able to be recycled through reprocessing. Taking these features, this work provided great potential for designing and preparing sustainable substitutes for bisphenol A epoxy resins in the high-performance applications.
Osteonecrosis of the femoral head (ONFH) is a devastating musculoskeletal disease characterized by the impaired circulation of bone. The purpose of this study was to explore the underlying mechanisms of the protective effect of icariin on the glucocorticoid-induced injury of bone microvascular endothelial cells (BMECs). Normal BMECs were extracted from the femoral heads by enzymatic isolation and magnetic-activated cell sorting methods. Dexamethasone and icariin were used to intervene BMECs in microfluidic organ chips, and phalloidin staining was conducted to observe the cell morphology and viability. Then next-generation transcriptome sequencing and real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were performed to identify the differentially expressed genes (DEGs) in different groups. Through the microfluidic organ chip, it can be observed that after dexamethasone intervention, the filamentous structure in cell fibers disappeared and the cell morphology changed from spindle to round until death. Icariin could relieve these changes and showed a protective effect on glucocorticoid-damaged BMECs. In addition, 201 DEGs were detected between the icariin protection group and the dexamethasone group, which were significantly enriched in 17 signaling pathways. 8 of the top ten selected hub genes (IL6, PTGS2, VEGFA, etc.) were confirmed by qRT-PCR. Transcription factors (TFs)-gene network showed 63 connections between 18 TFs and 12 DEGs. For instance, GATA2 could regulate 5 DEGs. The associations between 92 miRNA and 12 DEGs were visualized in a miRNA-gene network. The hub miRNA, has-mir-335–5p was predicted to interact with 8 DEGs (PTGS2, VEGFA, etc.). Microfluidic organ chips could provide excellent morphological results for cell experiments, by which it could be observed that icariin showed a protective effect on the glucocorticoid-induced injury of BMECs. Beside, these DEGs, possible regulatory TF (GATA2, FOXC1, etc.) and miRNA (has-mir-335–5p) might be dysregulated in the initiation of ONFH and have prospective importance in ONFH diagnosis and therapy.
Bismuth-rich Bi5O7Br is a promising photocatalyst for pollutant removal owing to its stability and appropriate band structure in comparison with bismuth oxybromide. However, bulk-phase Bi5O7Br suffers from poor light absorption and high charge recombination rates resulting in poor activity. Elemental doping is a powerful strategy to enhance photocatalytic activity. In this study, we prepared a series of Br auto-doped ultrathin Bi5O7Br nanotubes and explored the effect of Br doping on photocatalytic NO removal. The optimal doping content was determined via a photocatalytic NO removal experiment, which revealed the optimal ratio of Bi and Br was approximately 3:1. In situ diffuse reflectance infrared Fourier transform spectroscopy (In situ DRIFT) and density functional theory (DFT) studies revealed that NO removal mechanism catalyzed by Br doped Bi5O7Br. Our work presents a new strategy for the enhancement of photocatalytic pollutant degradation by bismuth oxyhalide photocatalysts.
The temperature monitoring of treated cancer cells is critical in photothermal therapy. Current methods of detecting intracellular temperatures have low accuracy and poor spatial resolution, which limits their application to photothermal therapy. Herein, a strategy for targeted recognition and selective capture of MCF-7 breast cancer cells based on fluorescent polymer poly(N-isopropylacrylamide-benzoxadiazole-2-vinyl-4,4-dimethyl azlactone, PNMV) and modified gold nanobipyramids (AuNBPs-PNMV) was developed for temperature sensing during photothermal therapy. A mucin-1 protein aptamer (Apt) was applied to selectively target mucin-1 protein overexpressed on the surfaces of the MCF-7 cells, which can reduce interference by affinity interaction between the Apt and proteins. During photothermal therapy, the significant AuNBPs photothermal effect increases the fluorescence intensity of PNMV with temperature. Irradiation of MCF-7 cells cultured with AuNBPs-PNMV@Apt by an 808 nm laser increases the temperature of the system, while the cells can be inactivated because of the remarkable AuNBPs-PNMV@Apt photothermal effect. The results indicate that variation in the fluorescence of AuNBPs-PNMV@Apt can be applied as thermometers to monitor the intracellular effect of photothermal therapy.
Exosomes are now raising focus as a prospective biomarker for cancer diagnostics and prognosis owing to its unique bio-origin and composition. Exosomes take part in cellular communication and receptor mediation and transfer their cargos (e.g., proteins, mRNA and DNA). Quantitative analysis of tumor-related nucleic acid mutations can be a potential method to cancer diagnosis and prognosis in early stages. Here we present an integrated microfluidic system for exosome on-chip isolation and lung cancer RNA analysis through droplet digital PCR (ddPCR). Gradient dilution experiments show great linearity over a large concentration range with R2 = 0.9998. Utilizing the system, four cell lines and two mutation targets were parallelly detected for mutation analysis. The experiments demonstrated mutation heterogeneity and the results were agree with cell researches. These results proved our integrated microfluidic system as a promising means for early cancer diagnosis and prognosis in the era of liquid biopsy.
Peracetic acid (PAA)-based system is becoming an emerging advanced oxidation process (AOP) for effective removal of organic contaminants from water. Various approaches have been tested to activate PAA, while no previous researches reported the application of metal-organic frameworks (MOFs) materials for PAA activation. In this study, zeolitic imidazole framework (ZIF)-67, a representative MOFs, was facile synthesized via direct-mixing method at room temperature, and tested for PAA activation and sulfachloropyridazine (SCP) degradation. The as-synthesized ZIF-67 exhibited excellent performance for PAA activation and SCP degradation with 100% of SCP degraded within 3 min, owing to the specific MOFs structure and abundant Co2+ sites. The pseudo-first-order kinetic model was applied to fit the kinetic data, with rate constant k1 of ZIF-67 activated PAA system 34.2 and 156.5 times higher than those of conventional Co3O4 activated PAA and direct oxidation by PAA. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis indicated that CH3C(O)OO· played a major role in this PAA activation system. Then, the Fukui index based on density functional theory (DFT) calculation was used to predict the possible reaction sites of SCP for electrophilic attack by CH3C(O)OO·. In addition, the degradation pathway of SCP was proposed based on Fukui index values and intermediates detection, which mainly included the S-N bond cleavage and SO2 extrusion and followed by further oxidation, dechlorination, and hydroxylation. Therefore, ZIF-67 activated PAA is a novel strategy and holds strong potential for the removal of emerging organic contaminants (EOCs) from water.
The efficient remediation of heavy metal complexes in water has become a difficult and challenging task owing to their high stability and strong mobility. In this study, a novel strategy was employed for highly efficient removal of Cu-citrate by using intimately coupled photocatalysis and biodegradation (ICPB) system with non-woven cotton fabric as a carrier. Experimental results showed that the ICPB system caused 94% Cu removal, which was higher than those of single photocatalysis. After 5 cycles, Cu removal efficiency could still reach 78% within 5 h. The existence of 0–40 mg/L citrate had negligible influence, whereas the presence of 60–100 mg/L citrate exhibited a limited adverse effect on Cu removal (~70%). The decomplexation of Cu-citrate was realized via the function of free radicals and microorganisms. Two main processes, such as bio-adsorption of Cu2+ by microorganisms, deposition of Cu0 on the surface of material, played important role in Cu removal from aqueous solution. The dominant microorganisms in the system were Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Chlorophyta, Planctomycetes, and Verrucomicrobia. Furthermore, the performance of ICPB system was also validated through treatment of other heavy metal complexes. This study provided a feasible strategy for the decontamination of heavy metal complexes in wastewater.
We propose a concept for ligase detection by conversion of aggregation-based homogeneous analysis into surface-tethered electrochemical assay through streptavidin (SA)-biotin interaction. Sortase A (SrtA) served as the model analyte and two biotinylated peptides (bio-LPETGG and GGGK-bio) were used as the substrates. SrtA-catalyzed ligation of the peptide substrates led to the generation of bio-LPETGGGK-bio. The ligation product (bio-LPETGGGK-bio) induced the aggregation and color change of SA-modified gold nanoparticles (AuNPs) through the SA-biotin interactions, which could be assayed by the colorimetric method. Furthermore, we found that the bio-LPETGGGK-bio could trigger the assembly of tetrameric SA proteins with the formation of the (SA-bio-LPETGGGK-bio)n assemblies through the same interactions. The above results were further confirmed by atomic force microscopy and fluorescent imaging. The insulated assemblies were in-situ fabricated at the SA-modified gold electrode, thus hindering the electron transfer of [Fe(CN)6]3−/4− and leading to an increase in the electron-transfer resistance. The capability of the method for the detection of SrtA both in vitro and Staphylococcus aureus (S. aureus) has been demonstrated. SrtA with a concentration down to 1 pmol/L has been determined by the electrochemical analysis, which is lower than that achieved by the colorimetric assay (50 pmol/L). By integrating the advantages of homogeneous reaction and heterogeneous detection, the strategy serves as an ideal means for the fabrication of various sensing platforms by adopting biotin-labeled and sequence-specific peptide or nucleic acid substrates.
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