Organization of an Artificial Multicellular System with a Tunable DNA Patch on a Membrane Surface.

Coordinating multiple artificial cellular compartments into a well-organized artificial multicellular system (AMS) is of great interest in bottom-up synthetic biology. However, developing a facile strategy for fabricating an AMS with a controlled arrangement remains a challenge. Herein, utilizing in situ DNA hybridization chain reaction on the membrane surface, we developed a DNA patch-based strategy to direct the interconnection of vesicles. By tuning the DNA patch that generates heterotrophic adhesion for the attachment of vesicles, we could produce an AMS with higher-order structures straightforwardly and effectively. Furthermore, a hybrid AMS comprising live cells and vesicles was fabricated, and we found the hybrid AMS with higher-order structures arouses efficient molecular transportation from vesicles to living cells. In brief, our work provides a versatile strategy for modulating the self-assembly of AMSs, which could expand our capability to engineer synthetic biological systems and benefit synthetic cell research in programmable manipulation of intercellular communications.

Research on the Authenticity of Mutton Based on Machine Vision Technology.

To realize the real-time automatic identification of adulterated minced mutton, a convolutional neural network (CNN) image recognition model of adulterated minced mutton was constructed. Images of mutton, duck, pork and chicken meat pieces, as well as prepared mutton adulterated with different proportions of duck, pork and chicken meat samples, were acquired by the laboratory's self-built image acquisition system. Among all images were 960 images of different animal species and 1200 images of minced mutton adulterated with duck, pork and chicken. Additionally, 300 images of pure mutton and mutton adulterated with duck, pork and chicken were reacquired again for external validation. This study compared and analyzed the modeling effectiveness of six CNN models, AlexNet, GoogLeNet, ResNet-18, DarkNet-19, SqueezeNet and VGG-16, for different livestock and poultry meat pieces and adulterated mutton shape feature recognition. The results show that ResNet-18, GoogLeNet and DarkNet-19 models have the best learning effect and can identify different livestock and poultry meat pieces and adulterated minced mutton images more accurately, and the training accuracy of all three models reached more than 94%, among which the external validation accuracy of the optimal three models for adulterated minced mutton images reached more than 70%. Image learning based on a deep convolutional neural network (DCNN) model can identify different livestock meat pieces and adulterated mutton, providing technical support for the rapid and nondestructive identification of mutton authenticity.

Recent Advances in DNA-Based Cell Surface Engineering for Biological Applications.

Due to its excellent programmability and biocompatibility, DNA molecule has unique advantages in cell surface engineering. Recent progresses provide a reliable and feasible way to engineer cell surfaces with diverse DNA molecules and DNA nanostructures. The abundant form of DNA nanostructures has greatly expanded the toolbox of DNA-based cell surface engineering and gave rise to a variety of novel and fascinating applications. In this review, we summarize recent advances in DNA-based cell surface engineering and its biological applications. We first introduce some widely used methods of immobilizing DNA molecules on cell surfaces and their application features. Then we discuss the approaches of employing DNA nanostructures and dynamic DNA nanotechnology as elements for creating functional cell surfaces. Finally, we review the extensive biological applications of DNA-based cell surface engineering and discuss the challenges and prospects of DNA-based cell surface engineering.

MoS2 and Fe2O3 co-modify g-C3N4 to improve the performance of photocatalytic hydrogen production.

Photocatalytic hydrogen production as a technology to solve energy and environmental problems exhibits great prospect and the exploration of new photocatalytic materials is crucial. In this research, the ternary composite catalyst of MoS2/Fe2O3/g-C3N4 was successfully prepared by a hydrothermal method, and then a series of characterizations were conducted. The characterization results demonstrated that the composite catalyst had better photocatalytic performance and experiment results had confirmed that the MoS2/Fe2O3/g-C3N4 composite catalyst had a higher hydrogen production rate than the single-component catalyst g-C3N4, which was 7.82 mmol g-1 h-1, about 5 times higher than the catalyst g-C3N4 (1.56 mmol g-1 h-1). The improvement of its photocatalytic activity can be mainly attributed to its enhanced absorption of visible light and the increase of the specific surface area, which provided more reactive sites for the composite catalyst. The successful preparation of composite catalyst provided more channels for carrier migration and reduced the recombination of photogenerated electrons and holes. Meanwhile, the composite catalyst also showed higher stability and repeatability.

G-Quadruplex-Induced Liquid-Liquid Phase Separation in Biomimetic Protocells.

Biomolecular condensates comprised of specific proteins and nucleic acids are now recognized as one of the key organizing mechanisms in eukaryotic cells. However, the specific roles played by the nucleic acid secondary structure and sequence in biomolecular phase separation are still not clear. Here, utilizing giant membrane vesicles (GMVs) as a protocell model, we found that single-stranded DNA (ssDNA) with a parallel G-quadruplex structure could functionally cooperate with a G-quadruplex-binding protein to form speckle-like puncta inside the GMVs. The clustering behavior is dependent on the structural diversity of G-quadruplexes, and the reversible clustering behavior implicated a new pathway in dynamically regulating the formation of biomolecular condensates. This finding represents a potential link between G-quadruplex-binding proteins and the resulting G-quadruplex-mediated biomolecular phase separation, which would gain insight into a wide range of biological processes associated with nucleic acid-modulated phase separation inside living cells.

PROKR1 delivery by cell-derived vesicles restores the myogenic potential of Prokr1-deficient C2C12 myoblasts.

Cell-derived vesicles (CDVs) have been investigated as an alternative to exosomes. Here, we generated CDVs from Prokineticin receptor 1 (PROKR1) overexpressing HEK293T cells using micro-extrusion. More than 60 billion PROKR1-enriched CDV (PROKR1Tg CDVs) particles with canonical exosome properties were recovered from 107 cells. With 25 µg/mL of PROKR1Tg CDVs, we observed delivery of PROKR1, significant reduction of apoptosis, and myotube formation in C2C12Prokr1-/- myoblasts that have lost their myogenic potential but underwent apoptosis following myogenic commitment. Expression levels of early and late myogenic marker genes and glucose uptake capacity were restored to equivalent levels with wild-type control. Furthermore, PROKR1Tg CDVs were accumulated in soleus muscle comparable to the liver without significant differences. Therefore, CDVs obtained from genetically engineered cells appear to be an effective method of PROKR1 protein delivery and offer promise as an alternative therapy for muscular dystrophy.

Logic-Gated Cell-Derived Nanovesicles via DNA-Based Smart Recognition Module.

Engineering cell-derived nanovesicles with active-targeting ligands is an important strategy to enhance the targeting efficiency. However, the enhanced binding capability to targeting cells also leads to the binding with nontarget cells that share the same biomarkers. DNA-based logic gate is a kind of molecular system that responds to chemical inputs by generating output signals, and the relationship between the input and the output is based on a certain logic. Thus, the DNA-based logic gate could provide a new approach to improve the delivery efficiency of the nanovesicle. In this work, we developed a DNA logic-gated module that coupled two tumor cell-targeting factors (e.g., low pH and a tumor cell biomarker) in a Boolean manner. Immobilization of this module on the surface of the nanovesicle enables the nanovesicle to sense tumor cell-targeting factors and regard these cues as inputs AND logic gate. With the guide of DNA-based logic gate, gold carbon dots (GCDs) encapsulated within nanovesicles were delivered into target cells, and then the intracellular redox status variation was reflected by fluorescence change of GCDs. Overall, we developed DNA logic-gated nanovesicles that contract different targeting factors into a unique tag for target cells. This facile functionalization strategy can pave the way for constructing smart nanovesicles and would broaden their application in the field of precision medicine and personalized treatment.

Potential Control of Oxygen Non-Stoichiometry in Cerium Oxide and Phase Transition Away from Equilibrium.

Cerium oxide (ceria, CeO2) is a technologically important material for energy conversion applications. Its activities strongly depend on redox states and oxygen vacancy concentration. Understanding the functionality of chemical active species and behavior of oxygen vacancy during operation, especially in high-temperature solid-state electrochemical cells, is the key to advance future material design. Herein, the structure evolution of ceria is spatially resolved using bulk-sensitive operando X-ray diffraction and spectroscopy techniques. During water electrolysis, ceria undergoes reduction, and its oxygen non-stoichiometry shows a dependence on the electrochemical current. Cerium local bonding environments vary concurrently to accommodate oxygen vacancy formation, resulting in changes in Ce-O coordination number and Ce3+/Ce4+ redox couple. When reduced enough, a crystallographic phase transition occurs from α to an α' phase with more oxygen vacancies. Nevertheless, the transition behavior is intriguingly different from the one predicted in the standard phase diagram of ceria. This paper demonstrates a feasible means to control oxygen non-stoichiometry in ceria via electrochemical potential. It also sheds light on the mechanism of phase transitions induced by electrochemical potential. For electrochemical systems, effects from a large-scale electrical environment should be taken into consideration, besides effective oxygen partial pressure and temperature.

Correlation Between Fractional Exhaled Nitric Oxide Levels and Efficacy of Inhaled Corticosteroids in Children With Bronchial Asthma.

To investigate correlation between fractional exhaled nitric oxide (FeNO) levels and efficacy of inhaled corticosteroids in children with bronchial asthma. Between October 2013 and December 2014, 133 cases of children with bronchial asthma were randomly divided into the glucocorticoid group (n = 67; inhaled with Seretide/Pulmicort) and the nonglucocorticoid group (n = 66; inhaled with short-acting ß2 receptor agonist if needed); and alternatively 72 cases of healthy children were regarded as the control group. FeNO, forced expiratory volume in 1 second to predicted value, forced expiratory volume in 1 second/forced vital capacity, induced sputum eosinophils (EOS)%, and total serum immunoglobulin (Ig) E and serum EOS% were detected and childhood asthma control test (C-ACT) scale was investigated pretreatment and 3 and 6 months posttreatment, respectively. FeNO levels, induced sputum EOS%, total serum IgE, and serum EOS% were significantly lower, whereas forced expiratory volume in 1 second to predicted value, forced expiratory volume in 1 second/forced vital capacity, and C-ACT scores were obviously improved in the glucocorticoid group 6 months posttreatment compared with those of pretreatment (all P < 0.05). FeNO levels, induced sputum EOS%, and total serum IgE were significantly lower, whereas C-ACT scores were significantly higher in the glucocorticoid group compared with those of the nonglucocorticoid group (all P < 0.05). In the glucocorticoid group, induced sputum EOS% and total serum IgE showed significantly positive correlations with FeNO levels (r = 0.73, P < 0.01; r = 0.56, P < 0.01), whereas C-ACT scores were negatively correlated with FeNO levels (r = -0.67, P < 0.01). FeNO levels might be correlated with efficacy of inhaled corticosteroids in children with bronchial asthma.

Disulfiram thermosensitive in-situ gel based on solid dispersion for cataract.

To improve the corneal permeability and water-solubility of disulfiram (DSF), which is an ocular drug for cataract, P188 was selected as a matrix to prepare solid dispersion of DSF (DSFSD) by hot melt method. The DSFSD was characterized by DSC, XRD, and IR, and the results suggested that DSF was amorphous in DSFSD. The DSFSD was added to borate buffer solution (BBS) contained 20% poloxamer P407 and 1.2% poloxamer P188 to form in-situ gel. In vitro and in vivo experiments revealed that DSFSD combined with in-situ gel (DSFSD/in-situ gel) increased the residence time and the amount of DSF penetrated through the corneal. The pharmacodynamics studies exhibited DSFSD/in-situ gel delayed the development of selenium-induced cataract at some content. These results investigated that DSFSD/in-situ gel as a drug delivery system can improve DSF ocular permeability.

Octa-arginine modified lipid emulsions as a potential ocular delivery system for disulfiram: A study of the corneal permeation, transcorneal mechanism and anti-cataract effect.

The purpose of the study was to design a novel octa-arginine (R8) modified lipid emulsion (LE) system for the ocular delivery of the lipophilic drug disulfiram (DSF). The influence of the particle size of the lipid emulsions and the presence of R8 on corneal permeation was studied. DSF-loaded lipid emulsions with different particle sizes (DSF-LE1, DSF-LE2, DSF-LE3) and DSF-loaded lipid emulsions modified with R8 (DSF-LE1-R8 and DSF-LE2-R8) were prepared. The Zeta potential of the lipid emulsions was changed from negative to a positive value after modification of R8. The mucoadhesion of different preparations was investigated, and DSF-LE1-R8 was found to produce the strongest mucoadhesion. The in vitro corneal penetration study and in vivo ocular distribution study showed that the R8 modified lipid emulsion (DSF-LE1-R8) with a nano particle size, exhibited the highest permeability and the largest amount of DDC distributed in ocular issues. Coumarin-6 labelled LE1-R8 displayed more homogeneous fluorescence with the deeper penetration into the cornea compared with other preparations at various times. Confocal laser scanning microscopy showed that, in addition to paracellular routes, LE-R8 could also transport across the corneal epithelium by transcellular routes as a result of increased uptake due to the R8 modification. Furthermore, the anti-cataract effect was evaluated and it was found that DSF-LE1-R8 exhibited a marked anti-cataract effect. Therefore, the lipid emulsions with nano-sized particles and modification of R8 were proposed as a potential ocular delivery system to improve the corneal penetration and ocular delivery of DSF.

[Simultaneous determination of four flavone C-glycosides in Phyllostachys edulis leaves by high-performance liquid chromatography with ultraviolet spectrometry].

High-performance liquid chromatography with ultraviolet spectrometer (HPLC-UV) was used to simultaneously detect the four flavone C-glycosides, i. e. orientin, isoorientin, vitexin and isovitexin. Analytes were separated with Waters XTerra MS C18 column (250 mm x 4.6 mm, 5 µm) using acetonitrile and 0.5% (φ) formic acid as mobile phase. The flow rate was set at 1.0 mL · min(-1) with the column temperature at 30 °C, and the detection wavelength was 360 nm. The calibration curve was linear over the concentration range of 0.1-10.0 mg · L(-1) for the mixed standard solution. Analytes were separated in 22 minutes, and the relative standard deviation values were all above 0.999. LOD values of standards were found to be between 0.03 and 0.07 mg · L(-1), and LOQ values were in the range of 0.04-0.08 mg · L(-1). After comparing the spectra (240-400 nm) of four flavone C-glycosides in mixed standards and the final product purified by macroporous resin, respectively, the curve shape and characteristic ultraviolet absorption wavelength of each flavone C-glycoside including orientin, isoorientin, vitexin and isovitexin were fitted well. The bamboo leaves sample was extracted by ethanol under reflux, and then partitioned with water and petroleum ether. The aqueous phase was added onto macroporous resin (AB-8), and the fraction of ethanol-water (40%, φ) was concentrated. It was found that the contents of orientin, isoorientin, vitexin and isovitexin relative to the fraction of ethanol- water were 13.73, 49.68, 7.85 and 30.70 mg · g(-1), respectively. In addition, the average recovery of the four flavone C-glycosides ranged from 34.90% to 87.64% with RSD values from 0.41% to 10.83%. The results showed that bamboo leaves sample had good stability and repeatability. The new method was used to analyze the four flavone C-glycosides quickly and provide quality control for commercial products.

Mechanistic studies of water electrolysis and hydrogen electro-oxidation on high temperature ceria-based solid oxide electrochemical cells.

Through the use of ambient pressure X-ray photoelectron spectroscopy (APXPS) and a single-sided solid oxide electrochemical cell (SOC), we have studied the mechanism of electrocatalytic splitting of water (H2O + 2e(-) → H2 + O(2-)) and electro-oxidation of hydrogen (H2 + O(2-) → H2O + 2e(-)) at ∼700 °C in 0.5 Torr of H2/H2O on ceria (CeO2-x) electrodes. The experiments reveal a transient build-up of surface intermediates (OH(-) and Ce(3+)) and show the separation of charge at the gas-solid interface exclusively in the electrochemically active region of the SOC. During water electrolysis on ceria, the increase in surface potentials of the adsorbed OH(-) and incorporated O(2-) differ by 0.25 eV in the active regions. For hydrogen electro-oxidation on ceria, the surface concentrations of OH(-) and O(2-) shift significantly from their equilibrium values. These data suggest that the same charge transfer step (H2O + Ce(3+) <-> Ce(4+) + OH(-) + H(•)) is rate limiting in both the forward (water electrolysis) and reverse (H2 electro-oxidation) reactions. This separation of potentials reflects an induced surface dipole layer on the ceria surface and represents the effective electrochemical double layer at a gas-solid interface. The in situ XPS data and DFT calculations show that the chemical origin of the OH(-)/O(2-) potential separation resides in the reduced polarization of the Ce-OH bond due to the increase of Ce(3+) on the electrode surface. These results provide a graphical illustration of the electrochemically driven surface charge transfer processes under relevant and nonultrahigh vacuum conditions.

A hybrid zeolitic imidazolate framework membrane by mixed-linker synthesis for efficient CO2 capture.

A ZIF-9-67 hybrid membrane on α-Al(2)O(3) support was prepared using mixed-linker synthesis. The gas permeation and selectivity data demonstrate that this membrane may have potential applications for efficient CO(2) capture from several industrial mixtures.

Measuring fundamental properties in operating solid oxide electrochemical cells by using in situ X-ray photoelectron spectroscopy.

Photoelectron spectroscopic measurements have the potential to provide detailed mechanistic insight by resolving chemical states, electrochemically active regions and local potentials or potential losses in operating solid oxide electrochemical cells (SOCs), such as fuel cells. However, high-vacuum requirements have limited X-ray photoelectron spectroscopy (XPS) analysis of electrochemical cells to ex situ investigations. Using a combination of ambient-pressure XPS and CeO(2-x)/YSZ/Pt single-chamber cells, we carry out in situ spectroscopy to probe oxidation states of all exposed surfaces in operational SOCs at 750 °C in 1 mbar reactant gases H(2) and H(2)O. Kinetic energy shifts of core-level photoelectron spectra provide a direct measure of the local surface potentials and a basis for calculating local overpotentials across exposed interfaces. The mixed ionic/electronic conducting CeO(2-x) electrodes undergo Ce(3+)/Ce(4+) oxidation-reduction changes with applied bias. The simultaneous measurements of local surface Ce oxidation states and electric potentials reveal the active ceria regions during H(2) electro-oxidation and H(2)O electrolysis. The active regions extend ~150 µm from the current collectors and are not limited by the three-phase-boundary interfaces associated with other SOC materials. The persistence of the Ce(3+)/Ce(4+) shifts in the ~150 µm active region suggests that the surface reaction kinetics and lateral electron transport on the thin ceria electrodes are co-limiting processes.

Heterogeneous films of ordered CeO(2)/Ni concentric nanostructures for fuel cell applications.

Heterogeneous films of ordered CeO(2)/Ni concentric nanostructures have been fabricated through template-assisted electrodeposition. The free-standing films of Ni metal (8 mum thickness) contain ordered arrays of ceria tubes (200 nm OD, 100 nm ID). Ni/CeO(2) coaxial nanotubes were also obtained by tuning experimental conditions. The interfacial contact area within the 3-dimensional oxide nanotube/nickel matrix is approximately 100 times greater than 2-dimensional thin films of nickel and ceria of the same area. The use of the film as an anode electrocatalyst/current collector is demonstrated in a solid oxide fuel cell.

Quantized magnetoresistance in atomic-size contacts.

When the dimensions of a metallic conductor are reduced so that they become comparable to the de Broglie wavelengths of the conduction electrons, the absence of scattering results in ballistic electron transport and the conductance becomes quantized. In ferromagnetic metals, the spin angular momentum of the electrons results in spin-dependent conductance quantization and various unusual magnetoresistive phenomena. Theorists have predicted a related phenomenon known as ballistic anisotropic magnetoresistance (BAMR). Here we report the first experimental evidence for BAMR by observing a stepwise variation in the ballistic conductance of cobalt nanocontacts as the direction of an applied magnetic field is varied. Our results show that BAMR can be positive and negative, and exhibits symmetric and asymmetric angular dependences, consistent with theoretical predictions.