Lubrication effects on droplet manipulation by electrowetting-on-dielectric (EWOD)

Electrowetting has a potential to realize stand-alone point-of-care (POC) devices. Here we report droplet-migration characteristics on oil-infused electrowetting-on-dielectric (EWOD) substrates. We prepare sparse micropillars to retain the oil layer in order to exploit the layer as a lubricating film. A physical model of the droplet velocity is developed, and effects of the lubrication, the oil viscosity, the droplet volume, and the thickness of solid and liquid dielectric layers are discussed. It is found that the droplet velocity is scaled as square of E, which differs from a relationship of cube of E for droplets sliding down on liquid-infused surfaces by gravity. Furthermore, our device achieves droplet velocity of 1 mm/s at the applied voltage of 15 V. The velocity is approximately tenfold as high as the same condition (applied voltage and oil viscosity) on porous-structure-based liquid-infused surfaces. The achieved high velocity is explained by a lubrication-flow effect.Comment: 16 pages, 10 figure

Concentrated protein body product derived from rice endosperm as an oral tolerogen for allergen-specific immunotherapy--a new mucosal vaccine formulation against Japanese cedar pollen allergy.

The endoplasmic reticulum-derived type-I protein body (PB-I) from rice endosperm cells is an ideal candidate formulation for the oral delivery of bioencapsulated peptides as tolerogens for allergen-specific immunotherapy. In the present study, PBs containing the deconstructed Japanese cedar pollen allergens Cryptomeria japonica 1 (Cry j 1) and Cry j 2 were concentrated by treatment with thermostable α-amylase at 90°C to remove the starch from milled rice powder, which resulted in a 12.5-fold reduction of dry weight compared to the starting material. The modified Cry j 1 and Cry j 2 antigens in this concentrated PB product were more resistant to enzymatic digestion than those in the milled seed powder despite the absence of intact cell wall and starch, and remained stable for at least 10 months at room temperature without detectable loss or degradation. The high resistance of these allergens could be attributed to changes in protein physicochemical properties induced by the high temperature concentration process, as suggested by the decreased solubility of the antigens and seed proteins in PBs in step-wise-extraction experiments. Confocal microscopy showed that the morphology of antigen-containing PB-Is was preserved in the concentrated PB product. The concentrated PB product induced specific immune tolerance against Cry j 1 and Cry j 2 in mice when orally administered, supporting its potential use as a novel oral tolerogen formulation

Comparison of resistance to digestive enzyme in rice seed powder and concentrated PB product.

<p>(a) Pepsin digestion of seed powder and concentrated PB product for 0, 1, 5, 15, 30, 60, and 120 min at 37°C. Samples consisted of 10 mg of seed powder or 1 mg of concentrated PB products. (b) Pepsin digestion of recombinant protein after extraction from transgenic rice seeds for 0, 0.5, 1, 3, 5, 15, 30, and 60 min.</p

Evaluation of shelf life of the concentrated PB product.

<p>Concentrated PB products were prepared from transgenic rice seeds and stored at room temperature for 10 month (Stocked PB). Ten month after, concentrated PB products were prepared again from the same transgenic rice seeds (Fresh PB). Total proteins were extracted from flesh and stocked concentrated PB products at the same time and subject to SDS-PAGE (CBB) and immunoblot (IB) analyses.</p

Component analysis of milled rice powder and concentrated PB product

<p>Component analysis of milled rice powder and concentrated PB product</p

Oral administration of rice seed powder and concentrated PB product.

<p>(a) The levels of serum allergen-specific IgE were examined by ELISA. (b) Allergen-specific splenic CD4⁺ T-cell proliferative responses were expressed as stimulation index. Data are expressed as the mean ± standard deviation (<i>n</i> = 3 mice per group). ** <i>P</i> < 0.01 and * <i>P</i> < 0.05 for the group of mice fed Tg-rice seed powder or Tg-PB product in comparison with the group of mice fed WT-rice seed powder or WT-PB product, respectively. WT-rice, wild type rice; Tg-rice, transgenic rice; WT-PB, wild-type concentrated PB; Tg-PB, transgenic concentrated PB.</p