Non-Equilibrium Large-Scale Membrane Transformations Driven by MinDE Biochemical Reaction Cycles.

The MinDE proteins from E. coli have received great attention as a paradigmatic biological pattern-forming system. Recently, it has surfaced that these proteins do not only generate oscillating concentration gradients driven by ATP hydrolysis, but that they can reversibly deform giant vesicles. In order to explore the potential of Min proteins to actually perform mechanical work, we introduce a new model membrane system, flat vesicle stacks on top of a supported lipid bilayer. MinDE oscillations can repeatedly deform these flat vesicles into tubules and promote progressive membrane spreading through membrane adhesion. Dependent on membrane and buffer compositions, Min oscillations further induce robust bud formation. Altogether, we demonstrate that under specific conditions, MinDE self-organization can result in work performed on biomimetic systems and achieve a straightforward mechanochemical coupling between the MinDE biochemical reaction cycle and membrane transformation.

Dynamic Detection of Active Enzyme Instructed Supramolecular Assemblies In Situ via Super-Resolution Microscopy.

Inspired by the self-assembly phenomena in nature, the instructed self-assembly of exogenous small molecules in a biological environment has become a prevalent process to control cell fate. Despite mounting examples of versatile bioactivities, the underlying mechanism remains less understood, which is in large hindered by the difficulties in the identification of those dynamic assemblies in situ. Here, with direct stochastic optical reconstruction microscopy, we are able to elucidate the dynamic morphology transformation of the enzyme-instructed supramolecular assemblies in situ inside cancer cells with a resolution below 50 nm. It indicates that the assembling molecules endure drastically different pathways between cell lines with different phosphatase activities and distribution. In HeLa cells, the direct formation of intracellular supramolecular nanofibers showed slight cytotoxicity, which was due to the possible cellular secretory pathway to excrete those exogenous molecules assemblies. In contrast, in Saos-2 cells with active phosphatase on the cell surface, assemblies with granular morphology first formed on the cell membranes, followed by a transformation into nanofibers and accumulation in cells, which induced Saos-2 cell death eventually. Overall, we provided a convenient method to reveal the in situ dynamic nanomorphology transformation of the supramolecular assemblies in a biological environment, in order to decipher their diverse biological activities.

Spontaneous Membrane Generation and Extension in a Dipeptide Single Crystal and Phospholipid Mixed System.

Self-reproduction is one of the most important characteristics of lipid vesicles for origin of life research. Most vesicle self-reproduction systems are based on fatty acid vesicles and spontaneous phospholipid vesicle production is difficult owing to the relatively high stability of these vesicles. Now, spontaneous phospholipid vesicle generation and extension in a dipeptide/phospholipid system is demonstrated. Dissolution of the dipeptide crystal provides both the driving force and phospholipid constituents for vesicle generation and extension. This study provides a new system to enhance the understanding of vesicle self-reproduction mechanisms.

Physical, antibacterial and antioxidant properties of chitosan films containing hardleaf oatchestnut starch and Litsea cubeba oil.

More and more attention was attached to food safety, it is necessary to endow food packaging films with good antibacterial and antioxidant properties Edible films based on chitosan (CH), hardleaf oatchestnut starch (HOS) and Litsea cubeba oil (LEO) were prepared by solution casting. The properties and structures of the blend film with different proportion (xCH/yHOS) were evaluated. The CH-HOS films were firstly prepared by blending CH solution with HOS paste. The tensile strength (TS) and DPPH radical scavenging ability of CH-HOS films increased from 27.33 MPa to 33.54 MPa and 20.67% to 52.34%, respectively, and water vapor permeability (WVP) decreased from 1.531 × 10-11 g m-1 pa-1 s-1 to 1.491 × 10-11 g m-1 pa-1 s-1, with the HOS content increased from the ratio of 1:0 to 1:1. Then, the LEO was added to 1CH-1HOS films. Tensile strength (TS), water vapor permeability, moisture absorption and total soluble matter (TSM) of the 1CH-1HOS film were remarkably decreased with 16%LEO. Meanwhile, the static contact angle and antimicrobial activity of 1CH-1HOS-16LEO film increased significantly. Hence, this blend film system has great potential for food packaging in the future.

Self-Assembled Double-Bundle DNA Tetrahedron for Efficient Antisense Delivery.

DNA nanostructures are promising biomaterials capable of arranging multiple functional components with nanometer precision. Here, a double-bundle DNA tetrahedron is rationally designed to integrate with antisense oligonucleotides silencing proto-oncogene c-raf and nuclear targeting peptides. The functionalized DNA tetrahedron can be internalized by A549 cells and assists the delivery of antisense oligonucleotides toward the nucleus to increase the chance to downregulate target mRNA in nucleus and cytoplasm. Antisense strands released from the tetrahedron in response to the intracellular reducing environment can inhibit cell proliferation at a low concentration without transfection reagent. Finally, efficient knockdown of c-raf gene is observed, which verified our design. This designer DNA-based nanocarrier system will open a new avenue for efficient delivery of nucleic acid drugs.

Directed Self-Assembly of Dipeptide Single Crystal in a Capillary.

Controlled growth of one-dimensional nanostructures is playing a key role in creating types of materials for functional devices. Here, we report procedures for controlled assembly of the dipeptide diphenylalanine (FF) into aligned and ultralong single crystals in a capillary. With the evaporation of solvent, nucleation of the crystal occurred in the confined region, and the crystal grew continuously with a supply of molecules from the concentration gradient system inside the capillary. Based on the "Knudsen regime", an ultralong aligned individual FF single crystal possessing an active optical waveguide property at macroscopic length scale could be obtained. Moreover, capillary is also an effective microdevice to investigate the disassembly process of the FF single crystals. This strategy has potentials to broaden the range of applications of aligned organic nanomaterials.

Disassembly of Dipeptide Single Crystals Can Transform the Lipid Membrane into a Network.

Coupling between cytoskeleton and membranes is critical to cell movement as well as organelle formation. Here, we demonstrate that self-assembled single crystals of a dipeptide, diphenylalanine (FF), can interact with liposomes to form cytoskeleton-like structures. Under a physiological condition, disassembly of FF crystals deforms and translocates supported lipid membrane. The system exhibits similar dynamic characteristics to the endoplasmic reticulum (ER) network in cells. This bottom-up system thus indicates that external matter can participate in the deformation of liposomes, and disassembly of the nanostructures enables a system with distinct dynamic behaviors.

Observation of intracellular interactions between DNA origami and lysosomes by the fluorescence localization method.

We obtained the fluorescence localization images of tube DNA origami nanostructures in NIH 3T3 cells for the first time. The fluorescence localization images of tube DNA origami nanostructures and TIRF images of lysosomes were combined and they revealed the detailed interactions between the two structures. Quantitative analysis illustrated that the tube origami can be captured as well as degraded by lysosomes with time.

Direct Observation of the Distribution of Gelatin in Calcium Carbonate Crystals by Super-Resolution Fluorescence Microscopy.

Biological organic-inorganic hybrid materials often achieve excellent properties and provide inspiration for the design of advanced materials. The organic phase plays a key role in determining the properties of biogenic materials, and the spatial arrangement of organic and inorganic phases provides direct evidence for interaction between the two phases. Super-resolution fluorescence microscopy was used to visualize the gelatin distribution in two different crystalline polymorphs of calcium carbonate (vaterite and calcite) and to investigate the process by which gelatin is excluded from the crystals. The results demonstrated that gelatin is distributed through vaterite microspheres in the form of nanoparticles, whereas it tends to accumulate on the edges of the calcite rhombohedra.

Effect of glucosamine and chitooligomer on the toxicity of arsenite against Escherichia coli.

Escherichia coli was selected as the sample to study the toxicity of arsenite in the presence of saccharides. The effect of glucosamine, N-acetylglucosamine, glucose, lactose, sucrose, glucosamine and cyclodextrin on the toxicity of arsenite against E. coli was investigated by microcalorimetry. The glucosamine and the tested chitooligomer decreased the toxicity of arsenite on cells of E. coli, and the effect of glucosamine was stronger than that of the chitooligomer. These results suggest that the glucosamine and chitooligomer may be employed as the assistant antidote for arsenite.

[Clinical study of terminating biochemical pregnancy and early clinical pregnancy with mifepristone and misoprostol].

OBJECTIVE: To explore the efficacy and safety of terminating biochemical pregnancy (the stage in which intrauterine or ectopic pregnancy cannot be confirmed) with mifepristone and misoprostol. METHODS: Mifepristone (150 mg) combined with misoprostol (600 microg) 3 days later were given to 500 biochemical pregnancies (G(1)), 500 early clinical pregnancies (G(2)) and 500 clinical pregnancies (G(3)) which were classified according to amenorrhea days, serum human chorionic gonadotropin-beta subunit (beta-hCG) and vaginal B-ultrasonic examinations. All were observed for 6 hours after taking misoprostol and returned for assessment per week. RESULTS: Expulsion of conceptus was G(1) 123 (24.6%, 123/500), G(2) 438 (87.6%, 438/500) and G(3) 467 (93.4%, 467/500). Failure rate was G(1) 6 (1.2%, 6/500), G(2) 24 (4.8%, 24/500) and G(3) 79 (15.8%, 79/500) for ongoing pregnancies, hospitalizations for suspected ectopic pregnancies and surgical intervention for heavy or long-time bleeding. Bleeding cases during the administration of mifepristone were G(1) 272 (54.4%, 272/500), G(2) 141 (28.2%, 141/500) and G(3) 87 (17.4%, 87/500); the mean bleeding days were G(1) (5.8 +/- 1.5), G(2) (9.0 +/- 2.9) and G(3) (14.3 +/- 5.9) days. Other side effects including abdominal pain, nausea, vomiting and diarrhea were low and light in each group, increasing with advancing gestational age. Menses recovery was 486 (97.2%, 486/500), 452 (90.4%, 452/500) and 433 (86.6%, 433/500) for each group on scheduled time. Satisfaction was 499 (99.8%, 499/500), 485 (97.0%, 485/500) and 369 (73.8%, 369/500) respectively. CONCLUSION: Mifepristone and misoprostol in combination is as safe, and effective for termination of biochemical pregnancies as ordinary medical abortion. It does not need to wait till ectopic pregnancy is excluded.