RESUMO
On Cu(100) surface, Auger electron spectroscopy (AES), Low Energy Electron Diffraction (LEED) and Scanning Tunnelling Microscopy (STM) were used to study (i) at room temperature (RT) the first steps of silicon growth and, (ii) at higher temperature, the dissolution process of silicon in Cu(100). The growth kinetics of Silicon onto Cu(100) at RT monitored by AES shows a quasi perfect layer-by-layer behaviour. After deposition at RT of about 5 silicon monolayers (ML), isochronal dissolution kinetics (rate of annealing of 1.5 degrees C/min) is recorded in a temperatures range [50-400 degrees C]. The slowdown observed in the kinetics dissolution for temperatures between 150 and 340 degrees C, reveals formation of an intermetallic superficial phase thermally stable in this range of temperature. LEED pattern and STM images show large domains of a rectangular (5 x 3) superstructure.
RESUMO
Amine functionalization of polystyrene microwells for covalent binding of DNA is described. Polystyrene support was first carboxylated by permanganate oxidation in diluted sulfuric acid. These functions were activated with water-soluble carbodiimide and grafted with N-methyl-1,3-propane diamine to introduce a free secondary amino group on the support. The samples were characterized by X-ray photoelectron spectroscopy and radiochemical assay. The conditions for covalent linkage of secondary amine on polystyrene microwells were optimized. Functionalized supports were used for covalent binding of a DNA capture probe for the detection of human cytomegalovirus in a sandwich hybridization assay. Sensitivity of the assay compared very well with a commercially available surface, Covalink-NH, microwell plate obtained by electromagnetic irradiation.
