PubMed Health⌕ Search

Biomedical subjects

Xiaohai Yang

Publications and source records attributed to Xiaohai Yang.

7 recordsLinked to original sources
PubMed2006

Quantitative intracellular molecular profiling using a one-dimensional flow system.

We report on the development of one-dimensional microfluidic bead arrays for rapid and quantitative molecular profiling of human cancer cells. This new bioanalytical platform integrates the rapid binding kinetics of suspension bead carriers, the multiplexing and encoding capabilities of gene/protein chips, and the liquid handling advantages of microfluidic devices. Using antibody-conjugated beads in a two-site "sandwich" format, we demonstrate that the proteomic contents of as few as 56 human lung epithelial cancer cells can be determined with high sensitivity and specificity. The results indicate that each cell contains approximately 6 x 10(5) copies of the tumor suppressor protein P53. We have further examined the expression changes of P53, c-Myc, and beta-Actin as a function of anticancer drug treatment and have validated these changes by using Western blotting. This ability to quantitatively analyze normal and diseased cells raises new possibilities in studying cancer heterogeneity and circulating tumor cells.

Animals↗
PubMed2006

Electrical switching of DNA monolayers investigated by surface plasmon resonance.

The switching of DNA monolayers between a "lying" and a "standing" state initiated by applying electric field, and the subsequent DNA hybridization at different states were investigated in a contactless, label-free mode by surface plasmon resonance (SPR) technique. The results showed that the strength of the electric field and surface coverage could influence the switching of DNA monolayers. In addition, it was found that DNA hybridization efficiency could be enhanced or decreased when DNA probes stood straight up or lay flat on the gold surface, depending on the potential of the gold substrate. The enhancement of DNA hybridization efficiency reached the maximum when surface coverage reached 5.87 x 10(12) molecules/cm(2) and the potential of gold substrate was more negative than -0.7 V (versus ITO-coated glass). The research may be helpful for the construction of sensitive biosensors, biochips, and nanoscale electronic devices.

Base Sequence↗
PubMed2006

Enhanced surface plasmon resonance with the modified catalytic growth of Au nanoparticles.

The catalytic growth of Au nanoparticles (AuNPs) has been employed in several analytical methods for improving the detection sensitivity, or integrated with the enzyme reactions for the quantitative detection of the respective substrates. However, the catalytic growth of Au nanoparticles do not work in some situations, such as surface plasmon resonance (SPR), electrochemistry, where metal matrices were used, because metal matrices used in these techniques, e.g. Au, are susceptible to metal deposition, which increased the background seriously. In this work, a SiO(2) layer was vapor-deposited on the gold film. The inhibition of metal deposition by this SiO(2) layer was investigated by SPR sensor. The results showed that the SiO(2) layer could avoid the deposition of metal on Au film. With the low background achieved by SiO(2)-coated Au films, sensitive detection of DNA hybridization using the catalytic growth of Au nanoparticles enhanced SPR was demonstrated. The work described here maybe helpful for the development of sensitive bioanalytical methods.

Catalysis↗
PubMed2002

A selective optode membrane for histidine based on fluorescence enhancement of meso-meso-linked porphyrin dimer.

A plasticized polymer film, poly(vinyl chloride) (PVC) incorporated with a specific porphyrin dimer, is shown to exhibit significant and analytical usefulness for optical response toward histidine. The porphyrin dimer containing a free-base porphyrin and a covalently linked metalloporphyrin is shown to be weakly fluorescent as a result of the photoinduced intramolecular electron transfer from the inner free-base porphyrin in singlet excited state to a low-spin cobalt(II). The fluorescence enhancement of the membrane by histidine is based on favorable extraction of histidine into the bulk organic membrane and complexation with the inner metallopophyrin moiety and inhibiting the electron transfer process. With the optode membrane described, histidine in a sample solution from 0.0045 to 1.53 mM can be determined. The calibration curve of the optode membrane for histidine shows a good correlation with the mathematically derived formalism and, thus, confirms the theoretically expected behavior. The sensor presented exhibits high selectivity toward histidine over several amino acids and common inorganic anions. The optical selectivity coefficients obtained for histidine over other biologically relevant amino acids and anions are shown to meet the selectivity requirements for the monitoring concentration levels of histidine in biological samples. The selective characteristic of the sensor has been discussed in the view of the coordination chemistry of metalloporphyrin.

Algorithms↗
PubMedDate not supplied

Photostable luminescent nanoparticles as biological label for cell recognition of system lupus erythematosus patients.

In this article, we report a method for cell recognition of system lupus erythematosus (SLE) patients that uses photostable luminescent nanoparticles as biological labels. The luminescent silica nanoparticles are prepared with a water-in-oil microemulsion (W/O) technique. The silica network is produced by the controlled hydrolysis of tetraethylorthosilicate (TEOS) in water nanodroplets with the initiation of ammonia (NH3.H2O). A luminescent compound, tris(2,2'-bipyridyl)dichlororuthenium(II)hexahydrate [Ru(II)(bpy)3]2+, is doped inside as a luminescent signaling element, and the most appropriate dye concentration for the preparation of the nanoparticles with a size of 28 +/- 4 nm has been determined. The luminescent silica nanoparticles are covalently immobilized with goat anti-human immunoglobulin G (IgG), which can recognize SmIgG+ B lymphocytes. We have used antibody-labeled nanoparticles to recognize target SmIgG+ B lymphocytes isolated from the circulating blood of SLE patients. It has been observed that a bioassay based on fluorescent nanoparticles can identify target cells selectively and efficiently. And fluorescent nanoparticle labels also exhibit high photostability. The experiment results have shown that this cell recognition method was an effective one as further proof of the diagnosis of SLE.

2,2'-Dipyridyl↗