Novel dimeric cholesteryl derivatives and their smart thixotropic gels.

Three novel LS(2)-type dimeric-cholesteryl derivatives (1-3), where S is a steroidal residue and L stands for a linker connecting the two S residues and contains three benzene rings and two amide and two carbamate groups, were designed and prepared. The compounds can gel a wide variety of organic solvents via three different ways, including mixing at room temperature, a heating-cooling cycle, and ultrasound treatment. SEM measurements revealed that the structures and the concentrations of the gelators, the nature of the solvent, and the preparation method employed have a great effect on the morphologies of the gel networks.

Enzyme-controlled self-assembly and transformation of nanostructures in a tetramethylbenzidine/horseradish peroxidase/H2O2 system.

Enzyme-assisted bottom-up nanofabrication has attracted considerable attention because it provides an ideal strategy for fabricating and tailoring well-defined nanostructures with desired properties under physiological reaction conditions. Here, we report self-assembly and transformation of nanostructures controlled by enzymatic kinetics in a system consisting of horseradish peroxidase (HRP), hydrogen peroxide (H(2)O(2)), and 3,3',5,5'-tetramethylbenzidine (TMB). In this system, several TMB derivatives, produced in the presence of the enzyme HRP at different concentrations, assemble into nanoscale structures in a variety of morphologies and colors.

New dimeric cholesteryl-based A(LS)2 gelators with remarkable gelling abilities: organogel formation at room temperature.

Three new dimeric cholesterol-based compounds of A(LS)(2) type, where A stands for aromatic component, S steroid moiety, and L a linker connecting the two units, have been designed and prepared. Gelation test in 30 solvents demonstrated that the compounds can gel some of the solvents and form 37 gels, of which 16 form spontaneously at room temperature (~25 °C). These gels possess smart thixotropic properties as revealed by rheological studies.

Multilayer assembly of nanowire arrays for dye-sensitized solar cells.

Vertically ordered nanostructures synthesized directly on transparent conducting oxide have shown great promise for overcoming the limitations of current dye-sensitized solar cells (DSCs) based on random networks of nanoparticles. However, the synthesis of such structures with a high internal surface area has been challenging. Here we demonstrate a convenient approach that involves alternate cycles of nanowire growth and self-assembled monolayer coating processes for synthesizing multilayer assemblies of ZnO nanowire arrays and using the assemblies for fabrication of DSCs.

Biosensing using nanoelectromechanical systems.

Nanoelectromechanical systems (NEMS) correlate analyte-binding events with the mechanical motions of devices in nanometer scales, which in turn are converted into detectable electrical or optical signals. Biosensors based on NEMS have the potential to achieve ultimate sensitivity down to the single-molecule level, provide rapid and real-time detection signals, be operated with extremely low power consumption, and be mass produced with low cost and high reproducibility. This chapter reviews fundamental concepts in NEMS fabrication, actuation and detection, and device characterization, with examples of using NEMS for sensing DNA, proteins, viruses, and bacteria.

Gaussian fluctuations in tethered DNA chains.

In a recent work [Gao et al., Appl. Phys.

Transparent superhydrophobic and highly oleophobic coatings.

We report a facile process for fabrication of transparent superhydrophobic and highly oleophobic surfaces through assembly of silica nanoparticles and sacrificial polystyrene nanoparticles. The silica and polystyrene nanoparticles are first deposited by a layer-by-layer assembly technique. The polystyrene nanoparticles are then removed by calcination, which leaves a porous network of silica nanoparticles.

Oligo(FcDC-co-CholDEA) with ferrocene in the main chain and cholesterol as a pendant group-preparation and unusual properties.

With ever-increasing need for thin, flexible, and functional materials in electrochemical systems, various techniques have been explored for creating materials used in fuel cells, batteries, electrochromic devices, solar cells, and sensors. In the present study, a novel ferrocene (Fc) and cholesterol (Chol)-containing oligomer, oligo(FcDC-co-CholDEA), was specially designed and prepared by putting Fc in the main chain and Chol as a side group. MALDI-TOF MS and freezing point depression measurements revealed that in average each oligomer contains three Fc units and three Chol units.

[Study on optical energy transmission in biotic tissues by Monte Carlo method].

Biotic tissues are a kind of highly scattering random media; studies on laser light propagation in biotic tissues play an important role in bio-medical diagnostics and therapeutics. The propagation and distribution of infinitely narrow photon beam in tissues are simulated by Monte Carlo method in this paper. Also presented are the energy distribution with regard to depths, light distribution in tissues, reflection and transmittance on the upper and lower surface.

Mutation screening based on the mechanical properties of DNA molecules tethered to a solid surface.

We report a rapid gene mutation screening method by making use of the mechanical properties of single-strand DNA (ssDNA) tethered to a solid surface. With proper temperature control, ssDNA in solution undergoes intrabase pairing and forms a specific complex 3D structure. By tethering such ssDNA strands to a solid surface, a DNA film can be formed.

Anti-icing superhydrophobic coatings.

We use nanoparticle-polymer composites to demonstrate the anti-icing capability of superhydrophobic surfaces and report direct experimental evidence that such surfaces are able to prevent ice formation upon impact of supercooled water both in laboratory conditions and in natural environments. We find that the anti-icing capability of these composites depends not only on their superhydrophobicity but also on the size of the particles exposed on the surface. The critical particle sizes that determine the superhydrophobicity and the anti-icing property are in two different length scales.

Water-in-oil gel emulsions from a cholesterol derivative: structure and unusual properties.

As the first example of cholesterol derivatives, butane-1,4-dicarboxamide of di-cholesteryl L-alaninate has been shown to form water-in-oil type gel emulsions. The oils can be n-alkanes (7 < or = n < or = 10) and commercial fuels. Importantly, the preparation of the gel emulsions is a simple agitation process at room temperature, heating, cooling, addition of a co-solvent, or other additional procedures is not necessary.

Th17 and natural Treg cell population dynamics in systemic lupus erythematosus.

Objective: To investigate the relative abundance and activities of Th17 cells and natural Treg cells in systemic lupus erythematosus (SLE).

Methods: Blood samples were collected from 50 adult patients with SLE. Samples were processed to detect Th17 cells and natural Treg cells by flow cytometry, and related gene expression was assessed by real-time reverse transcription-polymerase chain reaction.

Effects of average childhood dairy intake on adolescent bone health.

Objective: To evaluate the effects of usual childhood dairy intake on adolescent bone health.

Study Design: Dietary data collected in the Framingham Children's Study over 12 years were used to evaluate usual dairy consumption and adolescent bone health. Each child's average Food Pyramid servings were estimated from yearly sets of 3-day diet records.

Horseradish peroxidase-functionalized gold nanoparticle label for amplified immunoanalysis based on gold nanoparticles/carbon nanotubes hybrids modified biosensor.

This paper describes the combination of electrochemical immunosensor using gold nanoparticles (GNPs)/carbon nanotubes (CNTs) hybrids platform with horseradish peroxidase (HRP)-functionalized gold nanoparticle label for the sensitive detection of human IgG (HIgG) as a model protein. The GNPs/CNTs nanohybrids covered on the glass carbon electrode (GCE) constructed an effective antibody immobilization matrix and made the immobilized biomolecules hold high stability and bioactivity. Enhanced sensitivity was obtained by using bioconjugates featuring HRP labels and secondary antibodies (Ab(2)) linked to GNPs at high HRP/Ab(2) molar ratio.

Super water- and oil-repellent surfaces on intrinsically hydrophilic and oleophilic porous silicon films.

We demonstrate that porous Si films fabricated by a convenient gold-assisted electroless etching process, which possess a hierarchical porous structure consisting of micrometer-sized asperities superimposed onto a network of nanometer-sized pores, are able to induce a superhydrophobic phenomenon on an intrinsically hydrophilic hydrogen-terminated Si surface and a superoleophobic phenomenon on an intrinsically oleophilic self-assembled monolayer-coated Si surface. Through comparison with porous Si films consisting of vertically aligned straight pores, which are hydrophilic and oleophilic, we show that an overhang structure resulting from the hierarchical porous structure is essential to preventing water and oil from penetrating the texture of the films and inducing the observed macroscopic superhydrophobic and superoleophobic phenomena.

Label-free colorimetric detection of gelatinases on nanoporous silicon photonic films.

We report the development of a sensor platform for detection of gelatinases based on porous silicon photonic films. The sensor is made by spin-coating gelatin, a substrate protein to gelatinases, onto the porous silicon, which forms a thin, uniform, and smooth gel layer where samples can be directly spotted. The digestion products of gelatin by the active gelatinase present in the sample are able to enter the pores and induce color changes that can be detected by the naked eye.

Design and fabrication of micro-textures for inducing a superhydrophobic behavior on hydrophilic materials.

Artificial superhydrophobic surfaces are typically fabricated by tuning the surface roughness of intrinsically hydrophobic surfaces. We report here the design and fabrication of micro-textures for inducing a superhydrophobic behavior on hydrogen-terminated Si surfaces with an intrinsic water contact angle of approximately 74 degrees . The micro-textures consist of overhang structures with well-defined geometries fabricated by microfabrication technologies, which provide positions to support the liquid and prevent the liquid from entering into the indents between the micro-textures.

Elastin-calmodulin scaffold for protein microarray fabrication.

In this work, we report a new method to reversibly immobilize proteins to a surface in a functionally active orientation directly from cell lysate by employing a fusion protein consisting of a thermal-responsive elastin (ELP) domain as the surface anchor and a calcium-responsive calmodulin (CalM) domain for protein capturing. Incorporation of an M13 tag into recombinant proteins enables not only easy surface immobilization but also direct purification from cell lysates. The feasibility of concept was demonstrated using the M13-tagged yellow fluorescent protein (M13-YFP).

Low dairy intake in early childhood predicts excess body fat gain.

Objective: To estimate the effect of dairy intake in early childhood on the acquisition of body fat throughout childhood.

Research Methods And Procedures: Ninety-nine of the original 106 families enrolled in the Framingham Children's Study with a child age to 6 years at baseline were followed into adolescence through yearly clinic visits and periodic data collection throughout each year. Dairy intake for these analyses was derived from a mean of 15 days of diet records per subject collected before age 6.

Fabrication of antibody arrays using thermally responsive elastin fusion proteins.

A general method has been developed to immobilize antibodies onto an array surface by employing fusion proteins consisting of an elastin domain with tunable hydrophobic properties and an antibody-binding domain with high binding affinity and specificity for antibodies. Antibodies conjugated with the elastin fusion proteins can be directly printed on a self-assembled monolayer-modified glass slide in a functionally active orientation with a spatially defined pattern. An antibody array sensor for detection of tumor markers was fabricated to demonstrate the utility of the method.