Sloped-Gate Voltage Method for Improving Measurement of Poly-Si Nanowire FET in Aqueous Environment

Nanowire field-effect transistors are suited to study the activity of biomolecules in bionanotechnology. The changes of biomolecules process are efficiently affected the charge at the nanowire surface; thus, the electrical characterization of NW-FET is changed. Although NW-FET is a well-known device in bioapplications, however, the intrinsic electrical characterization of NW-FET effect on real electrical measurement is not well studied. We present herein a novel measurement method to avoid errors in electrical characteristic of nanowire field-effect transistors. A physical model is developed to explore the effect of the leakage current, which is influenced by the charging effect of an equivalent capacitor in a NW-FET. We also present a sloped-gate voltage method to reduce the effect of equivalent capacitor in air, liquid, and phosphate buffered solution. The application of the sloped-gate voltage method significantly increases the stability of electrical characterization measurements. This method can also be easily applied to biosensing experiments

Specific Unbinding Forces Between Mutated Human P‑Selectin Glycoprotein Ligand‑1 and Viral Protein‑1 Measured Using Force Spectroscopy

Protein tyrosine sulfation (PTS) is a key modulator of extracellular protein–protein interaction (PPI), which regulates principal biological processes. For example, the capsid protein VP1 of enterovirus 71 (EV71) specifically interacts with sulfated P-selectin glycoprotein ligand-1 (PSGL-1) to facilitate virus invasion. Currently available methods cannot be used to directly observe PTS-induced PPI. In this study, atomic force microscopy was used to measure the interaction between sulfated or mutated PSGL-1 and VP1. We found that the binding strength increased by 6.7-fold following PTS treatment on PSGL-1 with a specific antisulfotyrosine antibody. Similar results were obtained when the antisulfotyrosine antibody was replaced with the VP1 protein of EV71; however, the interaction forces of VP1 were only approximately one-third of those of the antisulfotyrosine antibody. We also found that PTS on the tyrosine-51 residue of glutathione S-transferases fusion-PSGL-1 was mainly responsible for the PTS-induced PPI. Our results contribute to the fundamental understanding of PPI regulated through PTS

The relationships among the diameter of microfibers, width of observation channel and flow rate of continuous phase.

<p>The relationships among the diameter of microfibers, width of observation channel and flow rate of continuous phase.</p

Microfluidic chip.

<p>Expanded view (A) and a photo (B) of the microfluidic chip: 1, inlets of center channels; 2 and 3, inlets of side channels; 4, cross junction; 5, outlet; 6, observation channel; 7, bottom layer disk; 8, screw orifices; 9, the scale bar = 11 cm. (C) is the geometry of the microfluidic channels.</p

Microfiber images.

<p>Microscopic images (A∼B, stained with Rhodamine B) and scanning electron microscopy images (C∼E) of microfibers.</p

Microfiber formation.

<p>The diagram of the microfluidic system and photographs of observation positions. 1, 2 wt % CaCl₂ solution; 2, deionized water; 3, alginate solution; 4, sunflower seed oil; 5, observation channel; 6, microfibers. The formation of microfibers: A, photograph of the microfiber in the observation channel; B, Photograph of the second cross junction; C, photograph of the first cross junction.</p

Cell culture of microfibers.

<p>Proliferation of GBM cells in microfibers. A. GBM cells; B. microfiber without cells; C. GBM in microfibers at the 1st day; D. GBM in microfibers at the 7th day. Arrows indicate GBM cells.</p

Characteristics of the microfibers.

<p>(A) The hysteresis curve of the microfibers containing MIO nanoparticles. (B) Release profiles of diclofenac from MIO-loaded microfibers without magnetic stimulation as the control (▵), with 2 minutes stimulation at the 10th, 30th and 60th minute (▴), with a 10-minute stimulation after the 20th minutes (•) and with a continuous stimulation from the beginning (○).</p

High-Throughput Screening of Sulfated Proteins by Using a Genome-Wide Proteome Microarray and Protein Tyrosine Sulfation System

Protein tyrosine sulfation (PTS) is a widespread posttranslational modification that induces intercellular and extracellular responses by regulating protein–protein interactions and enzymatic activity. Although PTS affects numerous physiological and pathological processes, only a small fraction of the total predicted sulfated proteins has been identified to date. Here, we localized the potential sulfation sites of Escherichia coli proteins on a proteome microarray by using a 3′-phosphoadenosine 5′-phosphosulfate (PAPS) synthase-coupled tyrosylprotein sulfotransferase (TPST) catalysis system that involves in situ PAPS generation and TPST catalysis. Among the 4256 E. coli K12 proteins, 875 sulfated proteins were identified using antisulfotyrosine primary and Cy3-labeled antimouse secondary antibodies. Our findings add considerably to the list of potential proteins subjected to tyrosine sulfation. Similar procedures can be applied to identify sulfated proteins in yeast and human proteome microarrays, and we expect such approaches to contribute substantially to the understanding of important human diseases