Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
Not a member yet
3266 research outputs found
Sort by
Metabolic-Activity-Based Assessment of Antimicrobial Effects by D2O-Labeled Single-Cell Raman Microspectroscopy
No full textTo combat the spread of antibiotic resistance, methods that quantitatively assess the metabolism-inhibiting effects of drugs in a rapid and culture-independent manner are urgently needed. Here using four oral bacteria as models, we show that heavy water (D2O)-based single-cell Raman micro- spectroscopy (D2O-Raman) can probe bacterial response to different drugs using the Raman shift at the C-D (carbon deuterium vibration) band in 2040 to 2300 cm(-1) as a universal biomarker for metabolic activity at single-bacterial-cell resolution. The "minimum inhibitory concentration based on metabolic activity" (MIC-MA), defined as the minimal dose under which the median Delta CD-ratio at 8 h of drug exposure is <= 0 and the standard deviation (SD) of the Delta C-D ratio among, individual cells is <= 0.005, was proposed to evaluate the metabolism-inhibiting efficacy of drugs. In addition, heterogeneity index of MIC-MA (MIC-MA-HI), defined as SD of C-D ratio, among individual cells, quantitatively assesses the among-cell heterogeneity of metabolic activity after drug regimens. When exposed to 1 X MIC of sodium fluoride (NaF), 1 X MIC of chlorhexidine (CHX), or 60 X MIC of ampicillin, the cariogenic oral pathogen Streptococcus mutans UA159 ceased propagation yet remained metabolically highly active. This underscores the advantage of MIC-MA over the growth-based MIC in being able to detect the "nongrowing but metabolically active" (NGMA) cells that underlie many latent or recurring infections. Moreover, antibiotic susceptible and resistant S. mutans strains can be readily discriminated at as early as 0.5 h. Thus, D2O-Raman can serve as a universal method for rapid and quantitative assessment of antimicrobial effects based on general metabolic activity at single-cell resolution
Hierarchical CoNi-Sulfide Nanosheet Arrays Derived from Layered Double Hydroxides toward Efficient Hydrazine Electrooxidation
No full textA hierarchical CoNi-sulfide nanosheet array is fabricated via an in situ reduction of CoNi-layered double hydroxide (LDH) nanosheets, then a vulcanization process. The material inherits the morphology of the LDH precursor, consisting of well-distributed CoNi-alloy@CoNi-sulfide nanoparticles with a core-shell structure, and demonstrates promising performance toward hydrazine electrooxidation
Bioinspired Coupling of Inorganic Layered Nanomaterials with Marine Polysaccharides for Efficient Aqueous Exfoliation and Smart Actuating Hybrids
No full textWS2 and marine alginate are perfectly coupled to ensure scalable production of exfoliated WS2 with unprecedented efficiency, further providing super mechanical properties and the photothermal effect to their composites. Combined with the water-intake and cation-binding capabilities of alginate, biomimetic soft devices are designed with stimuli-responsiveness and actuating properties, capable of serving as a photo-driven motor, a walking robot, and a gripper
RNAi-based targeted gene knockdown in the model oleaginous microalgae Nannochloropsis oceanica
No full textMicroalgae are promising feedstock for renewable fuels such as biodiesel, yet development of industrial oleaginous strains has been hindered by the paucity and inefficiency of reverse genetics tools. Here we established an efficient RNAi-based targeted gene-knockdown method for Nannochloropsis spp., which are emerging model organisms for industrial microalgal oil production. The method achieved a 40-80% success rate in Nannochloropsis oceanica strain IMET1. When transcript level of one carbonic anhydrase (CA) was inhibited by 6283% via RNAi, mutant cells exhibited photosynthetic oxygen evolution (POE) rates that were 68-100% higher than wild-type (WT) at pH 6.0, equivalent to WT at pH 8.2, yet 39-45% lower than WT at pH 9.0. Moreover, the mutant POE rates were negatively correlated with the increase of culture pH, an exact opposite of WT. Thus, a dynamic carbon concentration mechanism (CCM) that is highly sensitive to pH homeostasis was revealed, where the CA inhibition likely partially abrogated the mechanism that normally deactivates CCM under a high level of dissolved CO2. Extension of the method to another sequenced N. oceanica strain of CCMP 1779 demonstrated comparable performance. Finally, McrBC-PCR followed by bisulfite sequencing revealed that the gene knockdown is mediated by the CG, CHG and CHH types of DNA methylation at the coding region of the targeted gene. The efficiency, robustness and general applicability of this reverse genetics approach suggested the possibility of large-scale RNAi-based gene function screening in industrial microalgae
Porous graphdiyne applied for sodium ion storage
No full textSodium ion batteries have gained recognition as an intriguing candidate for next generation battery systems and large scale energy storage devices due to the natural abundance of sodium sources. In this study, we prepared bulk graphdiyne powder with a porous structure and explored its sodium storage properties. The assembled sodium ion batteries exhibited extraordinary electrochemical performance, including moderate specific capacity, long cycle life as well as excellent rate performance, which should be attributed to its unique three-dimensional porous structure, chemical stability and high electronic conductivity. We obtained a reversible capacity of 261 mA h g(-1) after 300 cycles at a current density of 50 mA g(-1). Even at a high current density of 100 mA g(-1), the as-prepared GDY electrodes delivered a moderate specific capacity of 211 mA h g(-1) after 1000 cycles, with an excellent capacity retention of 98.2%. The calculation results indicate that most intercalated Na cations stay in a large triangular hole in bulk material
Mutagenesis and redox partners analysis of the P450 fatty acid decarboxylase OleT(JE)
No full textThe cytochrome P450 enzyme OleT(JE) from Jeotgalicoccus sp. ATCC 8456 is capable of converting free long-chain fatty acids into alpha-alkenes via one-step oxidative decarboxylation in presence of H2O2 as cofactor or using redox partner systems. This enzyme has attracted much attention due to its intriguing but unclear catalytic mechanism and potential application in biofuel production. Here, we investigated the functionality of a select group of residues (Arg245, Cys365, His85, and Ile170) in the active site of OleTJE through extensive mutagenesis analysis. The key roles of these residues for catalytic activity and reaction type selectivity were identified. In addition, a range of heterologous redox partners were found to be able to efficiently support the decarboxylation activity of OleTJE. The best combination turned out to be SeFdx-6 (ferredoxin) from Synechococcus elongatus PCC 7942 and CgFdR-2 (ferredoxin reductase) from Corynebacterium glutamicum ATCC 13032, which gave the highest myristic acid conversion rate of 94.4%. Moreover, Michaelis-Menton kinetic parameters of OleTJE towards myristic acid were determined
Facile and Reliable in Situ Polymerization of Poly(Ethyl Cyanoacrylate)-Based Polymer Electrolytes toward Flexible Lithium Batteries
No full textPolycyanoacrylate is a very promising matrix for polymer electrolyte, which possesses advantages of strong binding and high electrochemical stability owing to the functional nitrile groups. Herein, a facile and reliable in situ polymerization strategy of poly(ethyl cyanoacrylate) (PECA) based gel polymer electrolytes (GPE) via a high efficient anionic polymerization was introduced consisting of PECA and 4 M LiClO4 in carbonate solvents. The in situ polymerized PECA gel polymer electrolyte achieved an excellent ionic conductivity (2.7 x 10(-3) S cm(-1)) at room temperature, and exhibited a considerable electrochemical stability window up to 4.8 V vs Li/Li+. The LiFePO4/PECA-GPE/Li and LiNi1.5Mn0.5O4/PECAGPE/Li batteries using this in-situ-polymerized GPE delivered stable charge/discharge profiles, considerable rate capability, and excellent cycling performance. These results demonstrated this reliable in situ polymerization process is a very promising strategy to prepare high performance polymer electrolytes for flexible thin-film batteries, micropower lithium batteries, and deformable lithium batteries for special purpose
Analysis of the Geometrical Evolution in On-the-Fly Surface-Hopping Nonadiabatic Dynamics with Machine Learning Dimensionality Reduction Approaches: Classical Multidimensional Scaling and Isometric Feature Mapping
No full textOn-the-fly trajectory-based nonadiabatic dynamics simulation has become an important approach to study ultrafast photochemical and photophysical processes in recent years. Because a large number of trajectories are generated from the dynamics simulation of polyatomic molecular systems with many degrees of freedom, the analysis of simulation results often suffers from the large amount of high-dimensional data. It is very challenging but meaningful to find dominating active coordinates from very complicated molecular motions. Dimensionality reduction techniques provide ideal tools to realize this purpose. We apply two dimensionality reduction approaches (classical multidimensional scaling and isometric feature mapping) to analyze the results of the on-the-fly surface-hopping nonadiabatic dynamics simulation. Two representative model systems, CH2NH2+ and the phytochromobilin chromophore model, are chosen to examine the performance of these dimensionality reduction approaches. The results show that these approaches are very promising, because they can extract the major molecular motion from complicated time-dependent molecular evolution without preknown knowledge
Fibrous carbon nanosheets from Kevlar nanofibrils: Compromising one and two dimensions of carbon nanomaterials for optimal capacitive performance
No full textWith cost advantages, low-dimensional carbon nanomaterials beyond graphene and carbon nanotube have aroused great interest in diverse fields. To optimize their electrochemical properties for energy storage, it is highly desired to exploit an efficient strategy to engineer their dimensionality and relevant physicochemical parameters. Kevlar was found to be able to serve as a universal precursor to produce 1-2D carbon nanomaterials of nanofibrils (diameter 20-60 nm) and nanosheets (thickness 2-5 nm). When combining thermal pyrolysis with mussel-inspired dopamine coating, an unprecedented type of carbon nanomaterials - fibrous carbon nanosheet (fiber diameter 14-16 nm and nanosheet thickness 30 -50 nm) was also produced with high surface area, N-doping and hierarchical porosity. They not only compromised the dimensionality of carbon nanofibrils and carbon nanosheets, but also showed high capacitance and rate capability, in contrast to low capacitance while high rate capability of carbon nanofibrils, as well as high capacitance while low rate capability of carbon nanosheets. With the capacitive properties comparable to graphene and carbon nanotube, they would offer an alternative supercapacitor electrode for low-cost energy storage. Their unique morphologies and super physical properties can also find functional applications in catalysis, batteries, fuel cells, environmental adsorption and electrochemical sensing. (C) 2017 Elsevier Ltd. All rights reserved
Activation of Actuating Hydrogels with WS2 Nanosheets for Biomimetic Cellular Structures and Steerable Prompt Deformation
No full textMacroscopic soft actuation is intrinsic to living organisms in nature, including slow deformation (e.g., contraction, bending, twisting, and curling) of plants motivated by microscopic swelling and shrinking of cells, and rapid motion of animals (e.g., deformation of jellyfish) motivated by cooperative nanoscale movement of motor proteins. These actuation behaviors, with an exceptional combination of tunable speed and programmable deformation direction, inspire us to design artificial soft actuators for broad applications in artificial muscles, nanofabrication, chemical valves, microlenses, soft robotics, etc. However, so far artificial soft actuators have been typically produced on the basis of poly(N-isopropylacrylamide) (PNiPAM), whose deformation is motived by volumetric shrinkage and swelling in analogue to plant cells, and exhibits sluggish actuation kinetics. In this study, alginate-exfoliated WS2 nanosheets were incorporated into ice-template-polymerized PNiPAM hydrogels with the cellular microstructures which mimic plant cells, yet the prompt steerable actuation of animals. Because of the nanosheet-reinforced pore walls formed in situ in freezing polymerization and reasonable hierarchical water channels, this cellular hybrid hydrogel achieves super deformation speed (on the order of magnitude of 10 degrees s), controllable deformation direction, and high near-infrared light responsiveness, offering an unprecedented platform of artificial muscles for various soft robotics and devices (e.g., rotator, microvalve, aquatic swimmer, and water-lifting filter)