Frederik Klauser

The surface properties of nanocrystalline diamond and nanoparticulate diamond powder and their suitability as cell growth support surfaces

Nanocrystalline diamond (NCD) films and nanoparticulate diamond powder (DP) are the two main representatives of diamond at the nanoscale. This study was designed to investigate the suitability of these biomaterials as cell growth supports and to determine surface characteristic properties best suited to cell attachment and proliferation. Surface topography, chemical termination and wetting properties of NCD- and DP-coated borosilicate glass substrates were correlated to attachment, proliferation and differentially regulated gene expression of human renal epithelial cells (HK-2 cell line) cultured on these surfaces. Hydrogen-terminated NCD (NCD-H) surfaces were shown to inhibit cell attachment, which indicates that the lack of functional polar groups prevents adherent cells from settling on a surface, whether nanostructured or not. In contrast to NCD-H, oxygen-terminated NCD (NCD-O) as well as DP surfaces demonstrated improved cell attachment, as compared to borosilicate glass, which is a commonly used material for cell growth supports. NCD-O not only revealed an increased cell attachment, but also a markedly increased proliferation rate. Finally, none of the investigated surface modifications appeared to cause adverse cellular reactions or markedly alter cellular phenotype.

Surface-assisted laser desorption/ionization-mass spectrometry using TiO2-coated steel targets for the analysis of small molecules

Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI–MS) measurements in the low-molecular-mass region, ranging from 0 to 1000 Daltons are very often difficult to perform because of signal interferences originating from matrix ions. In order to overcome this problem, a stainless steel target was coated with a homogeneous titanium dioxide layer. The layer obtained was further investigated for its ability to desorb small molecules, e.g., amino acids, sugars, poly(ethylene glycol) (PEG) 200, or extracts from Cynara scolymus leaves. The stability of the layer was determined by repeated measurements on the same target location, which was monitored by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) before and after surface-assisted laser desorption/ionization (SALDI) analysis. In addition, this titanium dioxide layer was compared with an already published method with titanium dioxide nanopowder as inorganic matrix. As a result of this work, the titanium dioxide layer produced minimal background interference, enabling simple interpretation of the detected mass spectra. Furthermore, the TiO2 coating provides a target that can be reused many times for SALDI–MS measurements.

Crystal structure of cis-diamminebis(nitrito-κN)platinum(II)

The PtII atoms are coordinated in a square-planar fashion. Extensive N—H⋯O bonding between neighbouring molecules results in an hydrogen-bonded framework which has the hxl topology.