Origin of the Instability of Octadecylamine Langmuir Monolayer at Low pH

It has been reported that an octadecylamine (ODA) Langmuir monolayer becomes unstable at low pH values with no measurable surface pressure at around pH 3.5, suggesting significant dissolution of the ODA molecule into the subphase solution (Albrecht, Colloids Surf. A 2006, 284-285, 166-174). However, by lowering the pH further, ODA molecules reoccupy the surface, and a full monolayer is recovered at pH 2.5. Using surface sum-frequency spectroscopy and pressure-area isotherms, it is found that the recovered monolayer at very low pH has a larger area per molecule with many gauche defects in the ODA molecules as compared to that at high pH values. This structural change suggests that the reappearance of the monolayer is due to the adsorbed Cl(-) counterions to the protonated amine groups, leading to partial charge neutralization. This proposition is confirmed by intentionally adding monovalent salts (i.e., NaCl, NaBr, or NaI) to the subphase to recover the monolayer at pH 3.5, in which the detailed structure of the monolayer is confirmed by sum frequency spectra and the adsorbed anions by X-ray reflectivity.

Heart rate recovery and chronotropic incompetence in patients with prehypertension

AIM

The study was aimed to evaluate the function of the autonomic nervous system by heart rate recovery (HRR) and chronotropic incompetence (CIc) in patients with prehypertension.

METHODS

Subjects were classified into three groups by JCN 7 REPORT: 1) hypertension in the case of systolic blood pressure of ≥140 mmHg or diastolic blood pressure of ≥90 mmHg; 2) prehypertension in the case of systolic blood pressure of 120~139 mmHg or diastolic blood pressure of 80~89 mmHg; and 3) normal in the case of systolic blood pressure of <120 mmHg and diastolic blood pressure of <80 mmHg. HRR and CIc in 147 subjects with prehypertension, 147 subjects with hypertension and 211 subjects with normal blood pressure were measured.

RESULTS

HRR was significantly lower in subjects with prehypertension than in subjects with normal blood pressure (37.27±11.93 vs. 34.17±11.03, P<0.05), but there was no significant difference between subjects with hypertension and subjects with prehypertension. With regard to the CIc, subjects with hypertension showed significantly higher frequency than both subjects with normal blood pressure and with prehypertension (P<0.05). The results of multiple regression analysis showed that the HRR was significantly influenced by such factors as age (P<0.001), waist size (P<0.001), HDL cholesterol (P<0.001), heart rate at rest (P<0.001), maximum heart rate (P=0.049) and maximum systolic blood pressure (P=0.007).

CONCLUSION

Subjects with prehypertension showed a lower HRR compared with those with normal blood pressure, which proves that the dysfunction of the autonomic nervous system also appears in patients with prehypertension, the previous stage of hypertension.

Charge-selective membrane protein patterning with proteoliposomes

A novel method to fabricate transmembrane protein (TP) embedded lipid bilayers has been developed, resulting in an immobilized, but biologically functioning TP embedded lipid layer precisely in the targeted patterns.

Characteristics of pleural effusions in systemic lupus erythematosus: differential diagnosis of lupus pleuritis

We investigated the clinical characteristics of pleural effusion in systemic lupus erythematosus (SLE). A prospective analysis of 17 SLE patients with pleural effusion (seven lupus pleuritis, eight transudative effusions and two parapneumonic effusions) was performed. Thirty non-SLE patients with pleural effusion were recruited as controls. A pleural fluid ANA titer ≥1:160 was found in 8/17 (47.1%) SLE patients and none of the 30 non-SLE patients (p = 0.0001). Pleural fluid to serum C3 ratios were significantly lower in SLE than in non-SLE (median (minimum-maximum) 0.29 (0.03-0.43) versus 0.52 (0.26-0.73), p = 0.0002). Among SLE patients, pleural fluid ANA titers ≥1:160 were more frequently found in patients with lupus pleuritis than in those with pleural effusion from causes other than lupus itself (85.7% versus 20.0%, p = 0.0152). Serum CRP levels were significantly increased in patients with lupus pleuritis compared with SLE patients with transudative pleural effusion (2.30 (0.30-5.66) versus 0.7 (0.12-1.47) mg/dl, p = 0.0062). In conclusion, pleural fluid ANA titer and serum CRP levels are significantly increased in lupus pleuritis.

The association of radiographic progression with serum R-spondin 1 (RSPO1) levels or Dickkopf-1 (DKK1)/RSPO1 ratios in rheumatoid arthritis patients: clinical evidence for reciprocal inhibition between DKK1 and RSPO1

OBJECTIVES

To investigate the clinical implications of serum levels of R-spondin 1 (RSPO1), a natural antagonist for Dickkopf-1 (DKK1), and of DKK1/RSPO1 ratios in rheumatoid arthritis (RA) patients.

METHOD

Serum DKK1 and RSPO1 levels were measured in 102 RA patients and 39 age- and gender-matched healthy controls. In addition, DKK1 and RSPO1 levels were determined prior to and 3 months after anti-tumour necrosis factor alpha (anti-TNF-α) therapy in 15 RA patients. Clinical and laboratory data and baseline radiographs of the hands and feet were obtained. Serial radiographs were evaluated in 83 RA patients. Radiographic joint damage was assessed by the modified Sharp/van der Heijde score (SHS).

RESULTS

Serum RSPO1 levels were significantly reduced whereas serum DKK1 levels and DKK1/RSPO1 ratios were significantly increased in RA patients compared with controls (all p < 0.0001). Anti-TNF-α treatment significantly suppressed DKK1/RSPO1 ratios (p < 0.01). In contrast to DKK1 or RSPO1 levels, the ratios were significantly associated with erosive disease, elevated acute phase reactants, Disease Activity Score in 28 joints (DAS28) > 3.2, and radiographic progression rate (all p < 0.05). Although the RA patients with radiographic progression exhibited significantly increased DKK1 and reduced RSPO1 levels (p < 0.05), only the DKK1/RSPO1 ratio (log-transformed) was found to be a significant predictor of subsequent radiographic progression [odds ratio (OR) 2.07, p < 0.01].

CONCLUSIONS

In this study, the presence of RSPO1 in the circulation was shown for the first time. Our results suggest that the serum DKK1/RSPO1 ratio represents a better predictor of structural progression than either DKK1 or RSPO1 levels alone in RA patients.

The fabrication of patterned gold nanoparticle arrays via selective ion irradiation and plasma treatment

A simple and facile method for the patterning of gold nanoparticles (GNPs) was described via selective ion irradiation and oxygen plasma etching. Thin Pluronic films containing HAuCI4 as the precursor of GNPs were selectively irradiated through a pattern mask with 200 keV proton ions to generate GNP-embedded Pluronic patterns. The Pluronic was then removed by an oxygen plasma etching process for the pattern formation of GNPs. Based on the results of the UV-Vis, FE-SEM, and EDX analyses, 50 μm negative-tone line patterns of the GNP-embedded Pluronic were successfully generated at a fluence of less than 1 x 10(16) ions/cm2. The changes in the morphology and elemental composition of the formed GNP-embedded Pluronic patterns with different time periods of oxygen plasma etching were investigated using an FE-SEM with an EDX. The experimental results demonstrated that the patterns of GNPs were effectively generated by the oxygen plasma etching of the formed GNP-embedded Pluronic patterns for 15 min. Furthermore, the XRD results revealed that GNPs in the patterns formed by ion irradiation were further grown during the subsequent oxygen plasma etching.

Actuation of digital micro drops by electrowetting on open microfluidic chips fabricated in photolithography

Basic manipulations of discrete liquid drops on opened microfluidic chips based on electrowetting on dielectrics were described. While most developed microfluidic chips are closed systems equipped with a top plate to cover mechanically and to contact electrically to drop samples, our chips are opened systems with a single plate without any electric contact to drops directly. The chips consist of a linear array of patterned electrodes at 1.8 mm pitch was fabricated on a glass plate coated with thin hydrophobic and dielectric layers by using various methods including photolithography, spin coating and ion sputtering. Several actuations such as lateral oscillation, colliding mergence and translational motion for 3-10 μL water drops have been demonstrated satisfactory. All these kinetic performances of opened chips were similar to those of closed chip systems, indicating superiority of a none-contact method for the transport of drops on opened microfluidic chips actuated by using electrowetting technique.

Active digital microfluidic paper chips with inkjet-printed patterned electrodes

Active, paper-based, microfluidic chips driven by electrowetting are fabricated and demonstrated for reagent transport and mixing. Instead of using the passive capillary force on the pulp to actuate a flow of a liquid, a group of digital drops are transported along programmed trajectories above the electrodes printed on low-cost paper, which should allow point-of-care production and diagnostic activities in the future.

Engineering hybrid polymer-protein super-aligned nanofibers via rotary jet spinning

Cellular microenvironments are important in coaxing cells to behave collectively as functional, structured tissues. Important cues in this microenvironment are the chemical, mechanical and spatial arrangement of the supporting matrix in the extracellular space. In engineered tissues, synthetic scaffolding provides many of these microenvironmental cues. Key requirements are that synthetic scaffolds should recapitulate the native three-dimensional (3D) hierarchical fibrillar structure, possess biomimetic surface properties and demonstrate mechanical integrity, and in some tissues, anisotropy. Electrospinning is a popular technique used to fabricate anisotropic nanofiber scaffolds. However, it suffers from relatively low production rates and poor control of fiber alignment without substantial modifications to the fiber collector mechanism. Additionally, many biomaterials are not amenable for fabrication via high-voltage electrospinning methods. Hence, we reasoned that we could utilize rotary jet spinning (RJS) to fabricate highly aligned hybrid protein-polymer with tunable chemical and physical properties. In this study, we engineered highly aligned nanofiber constructs with robust fiber alignment from blends of the proteins collagen and gelatin, and the polymer poly-ε-caprolactone via RJS and electrospinning. RJS-spun fibers retain greater protein content on the surface and are also fabricated at a higher production rate compared to those fabricated via electrospinning. We measured increased fiber diameter and viscosity, and decreasing fiber alignment as protein content increased in RJS hybrid fibers. RJS nanofiber constructs also demonstrate highly anisotropic mechanical properties mimicking several biological tissue types. We demonstrate the bio-functionality of RJS scaffold fibers by testing their ability to support cell growth and maturation with a variety of cell types. Our highly anisotropic RJS fibers are therefore able to support cellular alignment, maturation and self-organization. The hybrid nanofiber constructs fabricated by RJS therefore have the potential to be used as scaffold material for a wide variety of biological tissues and organs, as an alternative to electrospinning.

Patterning of gold nanoparticles on fluoropolymer films by using patterned surface grafting and layer-by-layer deposition techniques

The patterning of gold nanoparticles (GNPs) on the surface of a fluoropolymer substrate by using patterned surface grafting and layer-by-layer deposition techniques is described. The surface of a poly(tetrafluoroethylene-co-perfluorovinyl ether) (PFA) substrate was selectively implanted with 150 keV proton ions. Peroxide groups were successfully formed on the implanted PFA surface, and their concentration depended on the fluence. Acrylic acid was graft polymerized onto the implanted regions of the PFA substrate, resulting in well-defined patterns of poly(acrylic acid) (PAA) on the PFA substrate. The surface properties of the PAA-patterned PFA surface, such as chemical compositions, wettability, and morphology, were investigated. The surface analysis results revealed that PAA was definitely present on the implanted regions of the PFA surface, and the degree of grafting was dependent on three factors: fluence, grafting time, and monomer concentration. Furthermore, GNP patterns were generated on the prepared PAA-patterned PFA surface by layer-by-layer deposition of GNPs and poly(diallyldimethyl ammonium chloride). The multilayers of GNPs were deposited only onto the PAA-grafted regions separated by bare PFA regions, and the resulting GNP patterns exhibited good electrical conductivity.

Dynamics and mechanism of flame retardants in polymer matrixes: experiment and simulation

We investigate the dynamics and the mechanism of flame retardants in polycarbonate matrixes to explore for a way of designing efficient and environment-friendly flame retardants. The high phosphorus content of organic phosphates has been considered as a requirement for efficient flame retardants. We show, however, that one can enhance the efficiency of flame retardants even with a relatively low phosphorus content by tuning the dynamics and the intermolecular interactions of flame retardants. This would enable one to design bulkier flame retardants that should be less volatile and less harmful in indoor environments. UL94 flammability tests indicate that even though the phosphorus content of 2,4-di-tert-butylphenyl diphenyl phosphate (DDP) is much smaller with two bulky tertiary butyl groups than that of triphenyl phosphate (TPP), DDP should be as efficient of a flame retardant as TPP, which is a widely used flame retardant. On the other hand, the 2-tert-butylphenyl diphenyl phosphate (2-tBuDP), with a lower phosphorus content than TPP but with a greater phosphorus content than DDP, is less efficient as a flame retardant than both DDP and TPP. Dynamic secondary ion mass spectrometry and molecular dynamics simulations reveal that the diffusion of DDP is slower by an order of magnitude at low temperature than that of TPP but becomes comparable to that of TPP at the ignition temperature. This implies that DDP should be much less volatile than TPP at low temperature, which is confirmed by thermogravimetric analysis. We also find from Fourier transform infrared spectroscopy that Fries rearrangement and char formation are suppressed more by DDP than by TPP. The low volatility and the suppressed char formation of DDP suggest that the enhanced flame retardancy of DDP should be attributed to its slow diffusivity at room temperature and yet sufficiently high diffusivity at high temperature.

Micropatterning of cells on electron-irradiated poly(dimethylsiloxane) surface

In this study, a facile route to fabricate micropatterns of cells is presented on the basis of electron irradiation of poly(dimethylsiloxane) (PDMS). PDMS films were irradiated with electron beams through a pattern mask with micrometer-sized grids. After irradiation, the changes in the chemical composition, morphology, and wettability of the PDMS surface were investigated by using an X-ray photoelectron spectrometer, an atomic force microscope, and a contact anglometer. The results of the surface analysis revealed that the hydrophobic PDMS surface was changed into a hydrophilic one by the electron irradiation. Furthermore, on the basis of cell culturing on the selectively-irradiated PDMS, cells such as NIH3T3 and L929 were selectively adhered to and proliferated on the irradiated regions of the PDMS surface, resulting in the micropatterns of the cells on the PDMS surface.

Nanostructured metal/carbon hybrids for electrocatalysis by direct carbonization of inverse micelle multilayers

A synthetic strategy for the fabrication of graphitic carbon nanomaterials containing highly dispersed arrays of metal nanoparticles is reported. This synthetic strategy involves successive deposition of inverse micelle monolayers containing a metal precursor and reduction of the latter, followed by direct carbonization of the obtained multilayer structure of inverse micelles containing metal nanoparticles. Thus, a "direct-carbonization" concept, in which the block copolymer simultaneously serves as soft template and as carbon source, was combined with a multilayer buildup protocol. The inner architecture of the multilayer structures consisting of carbon and metal nanoparticles was studied by X-ray reflectivity, grazing incidence small-angle X-ray scattering, and cross-sectional transmission electron microscopy imaging. The hexagonal near ordering of the metal nanoparticles in the block copolymer micelle multilayers was by and large conserved after carbonization. The resulting carbon structures containing multilayers of highly dispersed metal nanoparticles exhibit superior electrocatalytic activity in formic acid and methanol oxidation, suggesting that they are promising electrode materials for fuel cells.