Overexpression of Δ12-Fatty Acid Desaturase in the Oleaginous Yeast <Emphasis Type="Italic">Rhodosporidium toruloides</Emphasis> for Production of Linoleic Acid-Rich Lipids

Under nutrient-limited conditions, the red yeast Rhodosporidium toruloides can accumulate neutral lipids, of which the compositional fatty acids are mainly saturated and mono-unsaturated ones with 16 or 18 carbon atoms. To improve the linoleic acid content in the lipids, we enabled galactose-inducible expression of the gene encoding Δ12-fatty acid desaturase (FADS) from Mortierella alpina or Fusarium verticillioides by integration of the corresponding expression cassettes into the genome of R. toruloides haploid and diploid strains. The relative linoleic acid content increased up to fivefold and the final linoleic acid titer reached 1.3 g/L under flask culture conditions. Our results suggested that R. toruloides may be further explored as cell factory for production of high-valued lipids and other fatty acid derivatives as bio-based chemicals and fuels.     

Substance P conjugated to CdTe quantum dots triggers cytosolic calcium concentration oscillations and induces quantum dots internalization in the pancreatic carcinoma cell line AR4-2J

Highly fluorescent CdTe quantum dots (QDs) stabilized by 3-mercaptopropionic acid were prepared by an aqueous solution approach and used as a fluorescent label to link substance P (SP) in studying the interaction of SP with NK-1 receptor, which was expressed on the AR4-2J cell line. Nonspecific adsorptions of CdTe QDs on the AR4-2J cell membrane were observed, whereas the QD-SP conjugates successfully crossed the cell membrane and entered the cytosol. SP is a neurotransmitter, and neurotransmitter-induced calcium concentration oscillation is a common phenomenon in diverse cells especially of secretory type. Cytosolic calcium concentration responses were studied in the AR4-2J cell line during stimulation with SP and QD-SP conjugates. The oscillations triggered by SP and QD-SP conjugates were dose-dependent and very similar. Such QD-SP conjugates readily internalized into the cytosol as would be expected of an active NK-1 ligand. Therefore QD-SP conjugates could be used successfully to study ligand and NK-1 receptor interactions in live cells. Our research may provide a meaningful reference for congener research.     

Bi2S3 nanomaterials: morphology manipulation and related properties

The Bi(2)S(3) nanomaterials with various morphologies such as nanorods, nanowires, nanowire bundles, urchin-like microspheres and urchin-like microspheres with cavities have been successfully synthesized through a simple hydrothermal method. Experimental results indicate that sulfur sources play crucial roles in determining the morphologies of Bi(2)S(3) products. Moreover, formation mechanisms of different Bi(2)S(3) nanostructures are discussed based on understanding of the growth habit of Bi(2)S(3) crystal. Finally, we also studied the morphologies-dependent electrochemical and optical properties of the as-synthesized Bi(2)S(3) nanomaterials.     

High electro-catalytic graphite felt/MnO<Subscript>2</Subscript> composite electrodes for vanadium redox flow batteries

A mild and simple synthesis process for large-scale vanadium redox flow batteries (VRFBs) energy storage systems is desirable. A graphite felt/MnO₂ (GF-MNO) composite electrode with excellent electrocatalytic activity towards VO²⁺/VO₂⁺ redox couples in a VRFB was synthesized by a one-step hydrothermal process. The resulting GF-MNO electrodes possess improved electrochemical kinetic reversibility of the vanadium redox reactions compared to pristine GF electrodes, and the corresponding energy efficiency and discharge capacity at 150 mA cm^?2 are increased by 12.5% and 40%, respectively. The discharge capacity is maintained at 4.8 A h L^?1 at the ultrahigh current density of 250 mA cm^?2. Above all, 80% of the energy efficiency of the GFMNO composite electrodes is retained after 120 charge-discharge cycles at 150 mA cm^?2. Furthermore, these electrodes demonstrated that more evenly distributed catalytic active sites were obtained from the MnO₂ particles under acidic conditions. The proposed synthetic route is facile, and the raw materials are low cost and environmentally friendly. Therefore, these novel GFMNO electrodes hold great promise in large-scale vanadium redox flow battery energy storage systems.     

4‐(N,N‐Dimethylamino)pyridine‐Embedded Nanoporous Conjugated Polymer as a Highly Active Heterogeneous Organocatalyst

We report herein for the first time the incorporation of a versatile organocatalyst, 4‐(N,N‐dimethylamino)pyridine (DMAP), into the network of a nanoporous conjugated polymer (NCP) by the “bottom‐up” approach. The resulting DMAP‐NCP material possesses highly concentrated and homogeneously distributed DMAP catalytic sites (2.02 mmol g^?1). DMAP‐NCP also exhibits enhanced stability and permanent porosity due to the strong covalent linkage and the rigidity of the “bottom‐up” monomers. As a result, DMAP‐NCP shows excellent catalytic activity in the acylation of alcohols with yields of 92–99 %. The DMAP‐NCP catalyst could be easily recovered from the reaction mixture and reused in at least 14 consecutive cycles without measurable loss of activity. Moreover, the catalytic acylation reaction could be performed under neat and continuous‐flow conditions for at least 536 h of continuous work with the same catalyst activity.     

Mechanically Strong Janus Poly(N-isopropylacrylamide)/Graphene Oxide Hydrogels as Thermo-responsive Soft Robots

Simple preparation of stimuli-responsive hydrogels with good mechanical properties and mild stimuliresponsiveness is essential for their applications as smart soft robots.Mechanically strong Janus poly(Nisopropylacrylamide)/graphene oxide (PNIPAM/GO) nanocomposite hydrogels with stimuli-responsive bending behaviors are prepared through a simple one-step method by using molds made of a Teflon plate and a glass plate.Residual oxygen in the air bubbles on the Teflon plate surface affects the polymerization and hence the cross-linking density,leading to the different swelling/deswelling rates of the two sides of the gels.Therefore,the hydrogels exhibit bending/unbending behaviors upon heating/cooling in water.The incorporation of GO nanosheets dramatically enhances the mechanical properties of Janus hydrogels.Meanwhile,the photo-responsive property of the GO nanosheets also imparts the hydrogels with remotecontrollable deformation under IR irradiation.The application of the Janus PNIPAM/GO hydrogels as thermo-responsive grippers is demonstrated.     

The Hydrogen Evolution Reaction in Alkaline Solution: From Theory,Single Crystal Models,to Practical Electrocatalysts

The hydrogen evolution reaction (HER) is a fundamental process in electrocatalysis and plays an important role in energy conversion for the development of hydrogen‐based energy sources. However, the considerably slow rate of the HER in alkaline conditions has hindered advances in water splitting techniques for high‐purity hydrogen production. Differing from well documented acidic HER, the mechanistic aspects of alkaline HER are yet to be settled. A critical appraisal of alkaline HER electrocatalysis is presented, with a special emphasis on the connection between fundamental surface electrochemistry on single‐crystal models and the derived molecular design principle for real‐world electrocatalysts. By presenting some typical examples across theoretical calculations, surface characterization, and electrochemical experiments, we try to address some key ongoing debates to deliver a better understanding of alkaline HER at the atomic level.     

A Two‐Photon H2O2‐Activated CO Photoreleaser

Carbon monoxide (CO) is proposed as an active pharmaceutical agent with promising pharmaceutical prospects, as it has been involved in multifaceted modulation of diverse physiological and pathological processes. However, questions remain for therapeutic application of inhaled CO attributed to the inherent great affinity between CO and hemoglobin. Therefore, a robust platform with the function of CO transport and controllable release, depending on the local status of an organism, is of prominent significance for effectively avoiding the side effects of CO inhalation and optimizing the biological regulation function of CO. Utilizing the oxidative stress biomarker H₂O₂ as a trigger and combining with photo‐control, a two‐photon H₂O₂‐activated CO photoreleaser, FB, featuring highly sensitive and specific H₂O₂ sensing and photocontrollable CO release, was developed and the vasodilation effect of CO against angiotensin II was demonstrated.     

Synthesis and properties of novel stilbene-twelve alkyl quaternary ammonium salts as antibacterial optical whitening agents

Four novel stilbene-twelve alkyl quaternary ammonium salts 5a–d were synthesized. All synthesized compounds were characterized by FT-IR, ¹H-NMR and elemental analysis. Compounds 5a–d showed efficient whitening effect on cotton fiber and high fastness. Furthermore, compound 5c showed better stability to light than C186 in aqueous solution. The preliminary biological experiment demonstrated compounds 5a–d possessed significant antibacterial activities. Among them, compound 5d turned out to be the most active compound against Candida albicans with MIC₅₀ 4 μg/mL as well as E. coli with MIC₅₀ 16 μg/mL.     

Incorporation of carboxylation multiwalled carbon nanotubes into biodegradable poly(lactic-co-glycolic acid) for bone tissue engineering

Biodegradable poly(lactic-co-glycolic acid) (PLGA)/carboxyl-functionalized multi-walled carbon nanotube (c-MWCNT) nanocomposites were successfully prepared via solvent casting technique. Rat bone marrow-derived mesenchymal stem cells (MSCs) were employed to assess the biocompatibility of the nanocomposites in vitro. Scanning electron microscopy (SEM) observations revealed that c-MWCNTs gave a better dispersion than unmodified MWCNTs in the PLGA matrix. Surface properties were determined by means of static contact angle, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analysis. The presence of c-MWCNTs increased the mechanical properties of the nanocomposites. Seven-week period in vitro degradation test showed the addition of c-MWCNTs accelerated the hydrolytic degradation of PLGA. In addition, SEM proved that the cells could adhere to and spread on films via cytoplasmic processes. Compared with control groups, MSCs cultured onto PLGA/c-MWCNT nanocomposites exhibited better adhesion and viability and also displayed significantly higher production levels of alkaline phosphatase (ALP) over 21 days culture. These results demonstrated that c-MWCNTs modified PLGA films were beneficial for promoting cell growth and inducing MSCs to differentiate into osteoblasts. This work presented here had potential applications in the development of 3-D scaffolds for bone tissue engineering.