Biomedical subjects

Ilona Kretzschmar

Publications and source records attributed to Ilona Kretzschmar.

3 recordsLinked to original sources

PubMed2006

Surface-anisotropic polystyrene spheres by electroless deposition.

Surfaces of sulfate-terminated polystyrene microspheres are anisotropically modified with silver nanoparticles covering 20-50% of the sphere surface using electroless deposition. A PDMS templating method is employed. Silver nanoparticles are found to deposit uniformly onto the exposed sphere surfaces. The deposition is diffusion-controlled and the nanoparticles adhere strongly to the polystyrene particles despite extensive exposure to ultrasonication. Silver content is confirmed by EDAX analysis. The final silver coverage is controlled via the PDMS pre-curing conditions.

Journal Article↗

PubMed2006

Electropolymerization on microelectrodes: functionalization technique for selective protein and DNA conjugation.

A critical shortcoming of current surface functionalization schemes is their inability to selectively coat patterned substrates at micrometer and nanometer scales. This limitation prevents localized deposition of macromolecules at high densities, thereby restricting the versatility of the surface. A new approach for functionalizing lithographically patterned substrates that eliminates the need for alignment and, thus, is scalable to any dimension is reported. We show, for the first time, that electropolymerization of derivatized phenols can functionalize patterned surfaces with amine, aldehyde, and carboxylic acid groups and demonstrate that these derivatized groups can covalently bind molecular targets, including proteins and DNA. With this approach, electrically conducting and semiconducting materials in any lithographically realizable geometry can be selectively functionalized, allowing for the sequential deposition of a myriad of chemical or biochemical species of interest at high density to a surface with minimal cross-contamination.

Benzaldehydes↗

PubMed1999

On the Structural Dichotomy of Cationic, Anionic, and Neutral FeS(2).

Structural and thermochemical aspects of the FeS(2)(+) cation are examined by different mass spectrometric methods and ab initio calculations using density functional theory. Accurate threshold measurements provide thermochemical data for FeS(+), FeS(2)(+), and FeCS(+), i.e., D(0)(Fe(+)-S) = 3.06 +/- 0.06 eV, D(0)(SFe(+)-S) = 3.59 +/- 0.12 eV, D(0)(Fe(+)-S(2)) = 2.31 +/- 0.12 eV, and D(0)(Fe(+)-CS) = 2.40 +/- 0.12 eV. Fortunate circumstances allow a refinement of the data for FeS(+) by means of ion/molecule equilibria, and the resulting D(0)(Fe(+)-S) = 3.08 +/- 0.04 eV is among the most precisely known binding energies of transition-metal compounds. The present results agree with previous experimental findings and also corroborate the computed data for FeS(+) and FeS(2)(+). Ab initio calculations predict a sextet ground state ((6)A(1)) for FeS(2)(+) with a cyclic structure. The presence of S-S and Fe-S bonds accounts for the fact that not only reactions involving the disulfur unit but also sulfur-atom transfer can occur. In contrast, the FeS(2)(-) anion is an acyclic iron disulfide. In the gas phase, neutral FeS(2) may adopt either acyclic or cyclic structures, which are rather close in energy according to the calculations.

Journal Article↗