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Trinitrotoluene, usually known as TNT, is a kind of chemical explosive with hazardous and toxic effects on the environment and human health. National and societal security concerns have dictated an increasing need for the analytical detection of TNT with rapidity, high sensitivity and low cost. This work demonstrates a novel method using L-cysteine-capped CdTe quantum dots (QDs) to assay TNT, based on the formation of a Meisenheimer complex between TNT and cysteine. The fluorescence (FL) of quantum dots quench because electrons of the QDs transfer to the TNT molecules via the formation of a Meisenheimer complex. TNT can be detected with a low detection limit of 1.1 nM. Studies on the selectivity of this method show that only TNT can generate an intense signal response. The synthesized QDs are excellent nanomaterials for TNT detection. In addition, TNT in soil samples is also analyzed by the proposed method.

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We report a novel method for biological thiols detection using ssDNA/silver nanoparticles system. The adsorbing ssDNA supplies silver nanoparticles high density charge to rescue nanoparticles from aggregation induced by salt. However, homocysteine (cysteine or glutathione) is conjugated more powerfully than ssDNA to AgNPs via Ag-S bond, which holds back ssDNA binding to AgNPs surface. When salt is added, AgNPs aggregation occurs and the corresponding color changes from yellow to brown after these biological thiols is introduced. A high sensitivity can be achieved using salt as an amplifier to assay thiols. In our study, a favorable linear correlation between the A(0)/A(x) ratio and homocysteine concentration was obtained in the range of 10 to 500 nM with a low detection limit of 10 nM, indicating that homocysteine could be analyzed at low concentration. A concentration as low as 300 nM homocysteine caused a visible color change. As well as, cysteine and glutathione can be detected at a detection limit of 50 nM and 100 nM, respectively. In addition, study on the selectivity of this method shows that only homocysteine, cysteine and glutathione can generate signal response.

Ethylene polymerization was performed with the TiO2 nanotube supported metallocene catalytic system. The effects of Al/Zr molar ratio and time in polymerization on the catalytic behavior of the catalysts and the morphologies of the polyethylene were investigated. The nanofibers, floccules and nanosheets of polyethylene were obtained by controlling the polymerization conditions. Because the nanotubes confined the direction of propagation of the polyethylene chains, nanofibers were attained by extrusion polymerization, while the amount of floccules increased with extended polymerization time and nanosheets were mainly produced at high Al/Zr molar ratios. The possible correlation between the polymerization conditions and polyethylene morphologies was elucidated. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011.