Kinetically Controlled Site-Specific Self-assembly of Hairy Colloids.

The solvophobicity-driven directional self-assembly of polymer-coated gold nanorods is a well-established phenomenon. Yet, the kinetics of this process, the origin of site-selectivity in the self-assembly, and the interplay of (attractive) solvophobic brush interactions and (repulsive) electrostatic forces are not fully understood. Herein, we use a combination of time-resolved (vis/NIR) extinction spectroscopy and finite-difference time-domain (FDTD) simulations to determine conversion profiles for the assembly of gold nanorods with polystyrene shells of distinct thicknesses into their (tip-to-tip) self-assembled structures. In particular, we demonstrate that the assembly process is highly protracted compared with diffusion-controlled rates, and we find that the assembly rate varies for different thickness values of the polymer shell. Our findings were rationalized using coarse-grained molecular dynamics simulations, which also corroborated the tip-to-tip preference in the self-assembly process, albeit with a uniform polymer coating. Utilizing the knowledge of quantified conversion rates for distinct colloidal species, we designed coassembling systems with different brush thicknesses, featuring "narcissistic" self-sorting behavior. This provides new perspectives for high-level supracolloidal self-assembly.

Theoretical analysis of the elastic free energy contributions to polymer brushes in poor solvent: A refined mean-field theory.

We consider polymer brushes in poor solvent that are grafted onto planar substrates and onto the internal and external surfaces of a cylinder using molecular dynamics simulation, self-consistent field (SCF), and mean-field theory. We derive a unified expression for the mean field free energy for the three geometrical classes. While for low grafting densities, the effect of chain elasticity can be neglected in poor solvent conditions, it becomes relevant at higher grafting densities and, in particular, for concave geometries. Based on the analysis of the end monomer distribution, we introduce an analytical term that describes the elasticity as a function of grafting density. The accuracy of the model is validated with molecular dynamics simulations as well as SCF computations and shown to yield precise values for the layer thickness over a wide range of system parameters. We further apply this model to analyze the gating behavior of switchable brushes inside nanochannels.

A nanofluidic system based on cylindrical polymer brushes: how to control the size of nanodroplets.

In molecular dynamics simulations we investigate the self-organized formation of droplets from a continuous flow of incoming nanoparticles. This transformation is facilitated by a cylindrical channel that is decorated with a polymer brush in a marginally poor solvent. We analyze droplet formation and propagation by means of simple scaling arguments which are tested in the simulations. Polymer brushes in marginally poor solvents serve as a pressure feedback system, exhibit a collapse transition under the moderate pressure of the incident flow, without the need for additional external stimuli, and finally close spontaneously after droplet passage. Our results qualitatively demonstrate the control of polymer brushes over continuous fluids and droplet formation, and its effectiveness as a means of fluid control can be used to design nanofluidic rectification devices that operate reliably under moderate pressure.

ß-arrestin 2 is essential for fluoxetine-mediated promotion of hippocampal neurogenesis in a mouse model of depression.

Over the last decade, the roles of ß-arrestins in the treatment of neuropsychological diseases have become increasingly appreciated. Fluoxetine is the first selective serotonin reuptake inhibitor developed and is approved for the clinical treatment of depression. Emerging evidence suggests that fluoxetine can directly combine with the 5-HT receptor, which is a member of the G protein-coupled receptor (GPCR) family, in addition to suppressing the serotonin transporter. In this study, we prepared a chronic mild stress (CMS)-induced depression model with ß-arrestin2-/- mice and cultured adult neural stem cells (ANSCs) to investigate the involvement of the 5-HT receptor-ß-arrestin axis in the pathogenesis of depression and in the therapeutic effect of fluoxetine. We found that ß-arrestin2 deletion abolished the fluoxetine-mediated improvement in depression-like behaviors and monoamine neurotransmitter levels, although ß-arrestin2 knockout did not aggravate CMS-induced changes in mouse behaviors and neurotransmitters. Notably, the ß-arrestin2-/- mice had a shortened dendritic length and reduced dendritic spine density, as well as decreased neural precursor cells, compared to the WT mice under both basal and CMS conditions. We further found that ß-arrestin2 knockout decreased the number of proliferating cells in the hippocampal dentate gyrus and suppressed the proliferative capability of ANSCs in vitro. Moreover, ß-arrestin2 knockout aggravated the impairment of cell proliferation induced by corticosterone and further blocked the fluoxetine-mediated promotion of mouse hippocampal neurogenesis. Mechanistically, we found that the 5-HT2BR-ß-arrestin2-PI3K/Akt axis is essential to maintain the modulation of hippocampal neurogenesis in depressed mice. Our study may provide a promising target for the development of new antidepressant drugs.

FTIR study of hydrogen bonds in coal under drop weight impact testing.

There are many hydrogen bonds in coal, which affect the chemical structure and properties of coal. FTIR has been applied to the characterization study of the hydrogen bonds of Dongpang coals, which were under drop weight impact. There exists five kinds of hydrogen bonds in the coal: free OH groups, OH...π, OH...OH, cyclic OH tetramers and OH...N. Absorption strength of intermolecular hydrogen bonds markedly declined after impact. Free OH groups mechanical-power chemical reacted in drop weight impact testing. The infrared spectrum were curve-resolved into their component bands. The absorption strength of various hydrogen bonds decreased with the increase of impact energy, but the trend was slowing. By statistical relationship between then, we find then complying with power function relationship. By comparing the exponents of fitted equations, we concluded that failure sensitivity sequence of hydrogen bonds to the impact: free OH groups > cyclic OH tetramers > OH...N > OH...π > OH...OH.

[CIinical study on treatment of Leber hereditary optic neuropathy].

OBJECTIVE: To investigate the effect of Wuzi Yanzong Decoction (WYD) in treating Leber hereditary optic neuropathy (LHON). METHODS: Thirty patients of LHON up to the requirement were assigned to two groups, the treated group administered with WYD plus coenzyme Q10, and the control group with coenzyme Q10 alone, all for 3 months. Patients' visual acuity, visual field, vision evoked potential (VEP) and their Chinese medicine syndrome were observed before and after treatment. RESULTS: After treatment, all the above-mentioned indexes were improved to some extents in the treated group, but showed no evident change in the control group excepting visual acuity, comparison between groups showed the differences were significant in all items. CONCLUSION: WYD shows certain clinical therapeutic effect for treatment of LHON.

[A novel microbeads-based chemiluminescence immunoassay for detecting human thyrotropin].

AIM: To establish a low cost and sensitive microbeads-based chemiluminescence immunoassay (CLEIA) for detecting human thyrotropin. METHODS: Thyrotropin in sera was captured by an alkaline phosphase-labeled mAb against TSH beta subunit and a FITC-labeled mAb against TSH alpha subunit. Captured thyrotropin was then isolated with immuno-magnetic beads conjugated with anti-FITC antibody and then quantified by chemiluminescence using adamanatane amine as luminescent substrate. RESULTS: The sensitivity of this assay is 0.004 mIU/L. The intra-assay CV and the inter-assay CV of the assay were 7.45% and 10.45%, respectively. The recovery rate was 91.4% -102.4%. The examination result of the assay correlates well with that of ACS-180 system. CONCLUSION: The CLELA for detecting TSH is low-cost, sensitive, specific and stable, and therefore may have a promising prospect in clinical application.