Steric vs. electrostatic effects in the nucleophilic addition to a hindered cyclohexanone

The relative importance of steric vs. electrostatic effects in the nucleophilic addition to (4R,6S)-4-(tert-butyldimethylsiloxy)-2,2,6-trimethylcyclohexanone (1), a well-known chiral building block, is investigated.     

Characterization of rhenium-silicon thin films

Rhenium-silicon thin films have been characterized as promising compounds of thermoelectric applications by means of analytical transmission electron microscopy and X-ray diffraction referring to composition, morphology, short-range order and phase formation. Beyond the discussion of the results some methodical aspects and problems are presented.     

Bio-selective surfaces by chemically amplified constructive microlithography

In this work a simple and rapid method for the creation of bio-selective surfaces is described. Specifically, electrochemical printing of an alkyl self-assembled monolayer, also known as “constructive microlithography”, was integrated with N-hydroxysuccinimide chemical group amplification to create patterns consisting of polyethyleneglycol (PEG) and octadecyltrichlorosilane (OTS) micrometer-size features. X-ray photoelectron spectroscopy (XPS) analysis was carried out near the C 1s ionization edge to characterize the patterns for the chemical groups formed in the near-surface region during the electrochemical oxidation and after functionalization. PEG patterns were then exposed to fluorescently labeled bovine serum albumin (BSA) to test their efficacy in reducing non-specific adsorption within defined areas. It was shown by fluorescence microscopy that the PEG functionalized portions of the patterns were effective in reducing the adsorption of bovine serum albumin. Finally, cell adhesion experiments were carried out on PEG patterns pre-treated with fibronectin to promote epithelial cell adhesion to non-PEGylated regions. Cell adhesion was assessed using EGFP-expressing epithelial cells and found to be highly selective for the fibronectin coated regions while maintaining healthy cell growth with gene expression.