Enhanced Detection of Protein in Urine by Droplet Evaporation on a Superhydrophobic Plastic

Protein in urine can be detected using a simple colorimetric output by evaporating droplets on a superhydrophobic (SH) surface. Evaporation on a SH surface allows fluid to dramatically concentrate; the weak surface adhesion allows the droplet of fluid to constantly decrease its footprint area and contact diameter. On a SH surface, pure water completely evaporates. Molecules in solution, however, are confined to a footprint that is 8.5 times smaller than the original and are greatly concentrated. By concentrating molecules, a 160 times improved detection sensitivity is achieved compared to controls. With the low‐cost fabrication method and simple technique, highly sensitive detection can be achieved in a low‐cost platform. Utility is demonstrated by detecting protein in urine in the pre‐eclampsia range (150–300 μgmL⁻¹) for pregnant women.     

Globotriaosyl ceramide (Gb3) expression in human tumour cells: intracellular trafficking defines a new retrograde transport pathway from the cell surface to the nucleus, which correlates with sensitivity to verotoxin

The verotoxin receptor globotriaosyl ceramide (Gb3) is overexpressed in an ovarian tumour resistant to chemotherapy. An overlay of frozen tumour sections shows extensive staining of the tumour cells with verotoxin B subunit. In addition, blood vessels within the tumour mass are stained. The sensitivity of ovarian tumour cells in vitro to verotoxin can be modulated by culturing the cells in sodium butyrate to obtain an approximately 5000-fold increase in susceptibility. This increased susceptibility is correlated with the intracellular targeting of verotoxin as monitored by using FITC-VT B subunit, in that prior to sodium butyrate treatment the toxin is internalized to a juxtanuclear (likely) Golgi location whereas, following butyrate treatment the intracellular toxin is distributed around the nucleus, consistent with endoplasmic reticulum and nuclear envelope location. This perinuclear location is similar to that found for drug-resistant variants of ovarian tumour cell lines. These results suggest that intracellular targeting of verotoxin to the perinuclear area results in increased cytotoxicity. Potentially such targeting may also occur in other human tumours.     

Supramolecular assembled nanostructure containing cubic silsesquioxane in aqueous solution

Micellization and aggregation behavior of amphiphilic cubic silsesquioxane-poly(ethylene oxide) (CSSQ-PEO) in aqueous solution was studied by Dynamic and Static Light Scattering (DLS and SLS), and Transmission Electron Microscopy (TEM). The effects of CSSQ-PEO concentration and temperature on particle size were also investigated. Above the critical aggregation concentration (CAC), a combination of unassociated single micelle and micellar aggregates is observed up to a certain level of CSSQ-PEO concentration as determined by DLS and TEM studies. The size of unassociated single micelles are found to be independent of CSSQ-PEO concentration while that of the micellar aggregates become larger at higher concentration due to the aggregation growth. Both studies revealed that a small CSSQ core is surrounded by PEO corona and found self-assembled nanostructure of CSSQ-PEO in aqueous solution. The molecular weight of micellar aggregates (Mw,agg), radius of gyration (Rg), and apparent aggregation number (Nagg) were evaluated by SLS measurement. The decrease in the particle size (described by hydrodynamic diameter: Dh) upon increasing temperature was observed because of the diminishing hydrophilicity of PEO. Surprisingly, Rg is also decreased at higher temperature assuming the dissociation of micellar aggregates by repulsive forces due to the crowding effect. The encapsulation property of CSSQ-PEO to model drug has also been studied. Our preliminary results from DLS and TEM studies showed the formation of CSSQ-PEO nanospheres containing drug in aqueous solution. The size of the drug loaded CSSQ-PEO nanospheres are found to be larger (250-300 nm) than that of the core-corona CSSQ-PEO micellar aggregates (approximatly 180 nm) in dilute aqueous solution.     

Micromechanical resonator with ultra-high quality factor

A 6.3 MHz Lame-mode square resonator with fully differential drive and sense electronics, exhibiting quality factor (Q) values over 1 million in ambient pressures as high as 200 Pa is reported. A maximum Q value of 1.6 million was experimentally measured for the resonator designed for this study. It was also experimentally observed that the Q value for the designed bulk mode resonator was relatively independent for pressures below 200 Pa, suggesting that the Q is pressure limited for pressure higher than 200 Pa.     

Shrink-film configurable multiscale wrinkles for functional alignment of human embryonic stem cells and their cardiac derivatives

A biomimetic substrate for cell-culture is fabricated by plasma treatment of a prestressed thermoplastic shrink film to create tunable multiscaled alignment "wrinkles". Using this substrate, the functional alignment of human embryonic stem cell derived cardiomyocytes is demonstrated.     

Photocurable epoxy/cubic silsesquioxane hybrid materials for polythiourethane: Failure mechanism of adhesion under weathering

A new inorganic–organic hybrid coating containing epoxy‐functionalized cubic silsesquioxane (CSSQ) has been developed, which can be polymerized cationically by UV radiation. This solvent‐free solution can be used as hybrid coating for polythiourethane (PTU) substrate. The surface properties of the coating film were determined by adhesion and scratch resistance. The excellent adhesion of coating films on the substrate was observed at the initial stage before weathering, but deteriorated after exposure to the sunshine. The low viscosity of hybrid coating solution (～ 15 mPa s) leads to fast curing and the formation of hybrid coating film during the photopolymerization reaction. The adhesion failure was evaluated by atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS) analyses. AFM images showed that the surface is smooth at the initial stage, but a texture surface was developed after weathering. The shrinkage of the hybrid film due to the increase in crosslinking density by postpolymerization would affect the surface roughness after weathering. XPS analysis indicated that the adhesion failure occurred by photodegradation of the PTU substrate during weathering. The weathering resistance was significantly improved by adding UV absorbers, which protected the polymer substrate from the photodegradation. The advantages of the hybrid coating include fast cure speed, solvent‐free formulation, and improved surface properties of the coating film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Investigation of thermomechanical properties and matrix–filler interaction on polyimide/graphene oxide composites

We report, the preparation of nanocomposites having polyimide (PI) as matrix and graphene oxide (GO) as filler, analyses of matrix–filler interactions, and enhancements in thermomechanical properties of PI/GO as compared with pristine PI. The matrix–filler interactions were analyzed by ¹H NMR, X‐ray photoelectron spectroscopy, and density functional theory calculations. The data suggested stronger matrix–filler interactions in PI/GO as compared with PI/G composites. The stronger matrix–filler interactions and homogeneous dispersion of fillers lead to a significant enhancement in mechanical properties in PI/GO nanocomposites. Thus, with just 1 wt% GO content, the modulus of PI/GO composite increased by ～106% as compared with pristine PI. Finally, thermal expansion coefficients of the nanocomposites are also investigated. A plausible hypothesis has been proposed in the text to explain the observed matrix–filler interactions and the subsequent property enhancements in nanocomposites. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Conformal Stretch Sensors for High Resolution Motion Sensing and Control

While motion sensors such as accelerometers are commonplace now, highly sensitive conformal sensors that can quantify fine motion with high resolution remain to be realized. Current strain sensors exhibit a trade‐off between dynamic range and strain sensitivity; these sensors therefore are not suitable for applications that require both large strain and excellent signal resolution, such as gesture control for virtual and augmented reality or feedback or prosthetics. Shape‐memory polymers coupled with thin films on stretchable elastomeric support substrates have recently emerged as fabrication platforms that improve strain sensor characteristics. Herein, skin‐mountable strain sensors are introduced, with large dynamic ranges (over 350%), higher gauge factor (GF) with linear responses to strain (from 0–150%), smaller footprint sizes, and less hysteresis compared to other sensors. It is demonstrated that these sensors are able to resolve down to 5° resolution of the proximal interphalangeal joint, which would enable gesture control for gaming and other motion sensing and control applications. Because these sensors have a small form factor and are low‐cost and disposable, such technology can find various electronic applications.     

Ultra-high-density phase-change storage using AlNiGd metallic glass thin film as recording layer

A nonchalcogenide inorganic blu-ray super-resolution near-field optical disk was successfully developed using an Al-based metallic glass as the recording layer. Data were recorded based on the large reflectivity change obtained during transformation from the amorphous state to the crystalline state upon laser irradiation. The optical and thermal properties of the Al₉₀Ni₃Gd₇ metallic glass thin film were studied. The crystallization and melting temperatures were higher and more thermally stable than that of conventionally used Ge₂Sb₂Te₅ chalcogenide phase-change recording material. Al₉₀Ni₃Gd₇ metallic glass also demonstrated fast phase-change response to blue laser. Dynamic recording performance of this new structure showed good carrier-to-noise ratio and readout stability.