Showing papers by "Tao Li published in 2011"

Sonic Hedgehog Pathway Is Essential for Maintenance of Cancer Stem-Like Cells in Human Gastric Cancer

Abstract: Abnormal activation of the Sonic hedgehog (SHH) pathway has been described in a wide variety of human cancers and in cancer stem cells (CSCs), however, the role of SHH pathway in gastric CSCs has not been reported. In this study, we investigated the possibility that abnormal activation of the SHH pathway maintained the characteristics of gastric CSCs. First, we identified cancer stem-like cells (CSLCs) from human gastric cancer cell lines (HGC-27, MGC-803 and MKN-45) using tumorsphere culture. Compared with adherent cells, the floating tumorsphere cells had more self-renewing capacity and chemoresistance. The cells expressing CSCs markers (CD44, CD24 and CD133) were also significantly more in tumorsphere cells than in adherent cells. More importantly, in vivo xenograft studies showed that tumors could be generated with 2×104 tumorsphere cells, which was 100-fold less than those required for tumors seeding by adherent cells. Next, RT-PCR and Western blot showed that the expression levels of Ptch and Gli1 (SHH pathway target genes) were significantly higher in tumorsphere cells than in adherent cells. The results of quantitative real-time PCR were similar to those of RT-PCR and Western blot. Further analysis revealed that SHH pathway blocked by cyclopamine or 5E1 caused a higher reduction in self-renewing capacity of HGC-27 tumorsphere cells than that of adherent cells. We also found that SHH pathway blocking strongly enhanced the efficacy of chemotherapeutic drugs in HGC-27 tumorsphere cells in vitro and in vivo but had no significant effect in adherent cells. Finally, we isolated the tumorspheres from gastric cancer specimen, these cells also had chemoresistance and tumorigenic capacity, and SHH pathway maintained the gastric CSLCs characteristics of tumorsphere cells from primary tumor samples. In conclusion, our data suggested that SHH pathway was essential for maintenance of CSLCs in human gastric cancer.

M13 Bacteriophage-Polymer Nanoassemblies as Drug Delivery Vehicles

Abstract: Poly(caprolactone-b-2-vinylpyridine) (PCL-P2VP) coated with folate-conjugated M13 (FA-M13) provides a nanosized delivery system which is capable of encapsulating hydrophobic antitumor drugs such as doxorubicin (DOX). The DOX-loaded FA-M13-PCL-P2VP assemblies had an average diameter of approximately 200 nm and their structure was characterized using transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. The particles were stable at physiological pH but could be degraded at a lower pH. The release of DOX from the nanoassemblies under acidic conditions was shown to be significantly faster than that observed at physiological pH. In addition, the DOX-loaded FA-M13-PCL-P2VP particles showed a distinctly greater cellular uptake and cytotoxicity against folate-receptor-positive cancer cells than folate-receptor-negative cells, indicating that the receptor facilitates folate uptake via receptor-mediated endocytosis. Furthermore, the DOX-loaded particles also had a significantly higher tumor uptake and selectivity compared to free DOX. This study therefore offers a new way to fabricate nanosized drug delivery vehicles.

Superlattice of rodlike virus particles formed in aqueous solution through like-charge attraction.

Abstract: Rodlike tobacco mosaic virus (TMV) has been found to assemble into a 2D superlattice in aqueous solution with hexagonally packed structures in the presence of Ba2+ through like-charge attraction wh...

Unexpected short- and medium-range atomic structure of sputtered amorphous silicon upon thermal annealing

Abstract: We investigate the structure of magnetron-sputtered (MS) amorphous silicon (a-Si) prepared under standard deposition conditions and compare this to pure ion-implanted (II) a-Si. The structure of both films is characterized in their as-prepared and thermally annealed states. Significant differences are observed in short- and medium-range order following thermal annealing. Whereas II a-Si undergoes structural relaxation toward a continuous random network, MS a-Si exhibits little change. Cross-sectional transmission electron microscopy reveals the presence of nanopores in the MS film consistent with reduced mass-density. Therefore, the short- and medium-range order of annealed, MS a-Si is tentatively attributed to these pores.

High-sensing properties of magnetic plasmon resonances in double- and triple-rod structures

Abstract: We numerically investigated the magnetic plasmon resonances in double-rod and triple-rod structures (DRSs and TRSs, respectively) for sensing applications. According to the equivalent circuit model, one magnetic plasmon mode was induced in the DRS. Due to the hybridization effect, two magnetic plasmon modes were obtained in the TRS. Compared with the electric plasmon resonance in a single-rod structure (SRS), the electromagnetic fields near the DRS and TRS were much more localized in the dielectric surrounding the structures at the resonance wavelengths. This caused the magnetic plasmon resonance wavelengths to become very sensitive to refractive index changes in the environment medium. As a result, a large figure of merit that is much larger than the electric plasmon modes of SRS could be obtained in the magnetic plasmon modes of DRS and TRS. These magnetic plasmon mode properties enable the use of DRSs and TRSs as sensing elements with remarkable performance.

Synthesis and electron microscopic analysis of the self-assembly of polymer and ferritin core-shell structures.

Abstract: Self-assembly of poly(4-vinylpyridine) (P4VP) and ferritin produced a spherical core-shell structure, which was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In particular, for better understanding, the organization of such core-shell nanostructures, an optimal protocol for preparation of TEM thin sectioning of ferritin-P4VP composites, was developed. It entails fixing the ferritin-P4VP complex with 2.5% glutaraldehyde and infiltrating it with a mixture of acetone/resin while omitting the OsO(4) postfixation and ethanol dehydration steps of the conventional protocol. Using this method, a round-shaped thin section structure with unevenly distributed dark and white components was observed. The dark component from the thin section structure was determined to contain ferritin by energy-filtered TEM imaging and iron element mapping, whereas the white part was identified as P4VP by its energy dispersive X-ray spectroscopy (EDS) spectrum.

Production method of composite mould plate agent synthesized silicon-aluminum phosphate molecular sieve

Abstract: The invention relates to a preparation method of a silicon-aluminium phosphate molecular sieve synthesized by a composite template agent The structural formula of the molecular sieve is (02-30)R: (Si001-03 Al001-1 P001-09): (10-400)H2O, wherein R is a tetraethyl ammonium hydroxide/diethylamine composite template agent, and the composite template agent is x tetraethylammonium hydroxide+(1-x) diethylamine, wherein x is equal to between 0 and 1 Compared with the prior art, the composite template agent (tetraethyl ammonium hydroxide/diethylamine) has low synthesis cost for synthesizing the silicon-aluminium phosphate molecular sieve and is easy for industrial production, and when used as a catalyst in the preparation of low-carbon olefin from methanol, the template agent has slow reaction cocking rate and deactivation rate, and long activity time and service life, and has the advantages of high feed stock conversion, high selectivity for low-carbon alkene such as ethylene, propylene, and the like