Bioimprinting of polymers and sol-gel phases. Selective detection of yeasts with imprinted polymers

Coated quartz crystal microbalances were modified with a surface-imprinting process using whole yeast cells. These molded polymer and sol-gel surfaces show honeycomb-like structures as shown by atomic force microscopy. Reinclusion of cells allows a selective on-line monitoring of these microorganism concentrations in water over 5 orders of magnitude. The sensitivity to cells holds up in growth media up to 21 g/L. Even cell fragments can be detected in flowing conditions. The highly robust polymers on the sensor devices are suitable for biotechnological applications.

Double molecular imprinting--a new sensor concept for improving selectivity in the detection of polycyclic aromatic hydrocarbons (PAHs) in water

Highly selective and robust polymer coatings for the detection of polycyclic aromatic hydrocarbons (PAHs) in liquid media have been generated by use of an innovative method of molecular imprinting. By imprinting with two different templates, the selectivity of the polyurethanes used was increased by creating diffusion pathways and molecular cavities. Analyte inclusion was detected both by fluorescence and by use of mass-sensitive transducers. It is possible to optimize layers in respect of the extraction of two different analytes or to achieve extremely high selectivity for a distinct analyte. In this way coatings can be tuned to the lean chrysene, e.g., and it is enriched by a factor of approximately fifty compared with the more quadratic pyrene with the same number of aromatic rings. Measurements of PAHs in water were also performed with a quartz crystal microbalance, which shows that humic acids are not incorporated by the layers and thus do not influence the fluorescence properties of the layers.

Synthetic receptors as sensor coatings for molecules and living cells

Non-covalent molecularly imprinted polymers are applied as sensitive coatings to planar waveguides and mass-sensitive devices for the selective detection of various groups of analytes in the gaseous and aqueous phases. Cavity imprinting in the bulk of the sensor material as well as surface imprinting techniques are used to enrich analytes ranging from sub-nanometres to micrometres in analyte size. The coated devices provide sensitivity to e.g. polycyclic aromatic hydrocarbons, xanthine derivatives, complex coffee samples and whole microorganisms.

Quality control of automotive engine oils with mass-sensitive chemical sensors--QCMs and molecularly imprinted polymers

Molecularly imprinted polyurethanes were used as sensor materials for monitoring the degradation of automotive engine oils. Imprinting with characteristic oils permits the analysis of these complex mixtures without accurately knowing their composition. Mass-sensitive quartz crystal microbalances (QCMs) coated with such layers exhibit mass effects in addition to frequency shifts caused by viscosity, which can be compensated by an uncoated quartz or a non-imprint layer. Incorporation of degradation products into the imprinted coatings is a bulk phenomenon, which is proven by variation of the sensor layer height. Therefore, the resulting sensor effects are determined by the degradation products in the oil.

The Effect of Quinolyl Endgroups on Podand Fluctuations-1-DNMR and 2D-EXCSY-NMR of Co(II)-Complexes

Ligand fluctuations in complexes [Co(Kr5)]X2 (Kr 5 = 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane) with X = ClO4 -, CF3SO3 - can be detected by NMR spectroscopy above room temperature in inert solvents such as nitromethane. This unusually slow ligand movement is due to the strong coordination of the quinolyl end groups to the Co(II) ion as demonstrated through measurements with oligo-ethylene-glycols. In contrast to the 13C spectra, the 1H 2 D EXCSY NMR spectra reveal cross peaks which are due to a magnetisation exchange between the chemically non-equivalent protons in the -CH2- groups of the podand. This process is associated with a movement of the chain segments towards each other.