Nanotiterplates for combinatorial chemistry

Micro fluid segment technique for screening and development studies on Danio rerio embryos

The applicability of micro fluid segments for studying the behaviour of multicellular systems, in particular embryonic development, has been investigated. It was found that eggs from the zebrafish Danio rerio can be introduced into micro fluid segments without serious damage by using perfluoromethyldecalin (PP9) as the carrier liquid and Teflon (PTFE) as the tube material. The development processes of fish embryos were observed over a time period of 80 hours, until hatching time. After five days, the fish larvae were brought out of the micro fluid segments and transferred into breeding reservoirs. Effects of the membrane-damaging anionic surfactant sodium dodecyl sulfate (SDS) alone and SDS with the addition of CuCl(2) (copper(II) chloride) were investigated. By analyzing different end points, we found inhibiting and also supporting effects on the development of the embryos. Low SDS concentrations with and without copper(II) ions were supportive, while higher SDS concentrations led to negative impacts on the development of the embryos. The results showed that automated micro screening processes with complex biological systems can be performed using microfluidic systems and are applicable for future toxicological and drug screening studies.

Chip devices for miniaturized biotechnology

Chip devices were introduced in chemistry and molecular biology to improve the read-out of information from molecular systems by efficient analytical procedures and to organize automated experiments. Biochips and chip reactor systems are of interest for cellular processes, too, and can be regarded as components in interfaces for the information exchange between living nature and digital electronic systems. In this minireview, different types of chip reactors for biotechnological applications like nanotiterplates, chip thermocyclers and devices for segmented flow operations are discussed. Finally, an outlook is given on the application of chip reactor systems, which are promising tools for automated experiments with highly parallelized screening procedures, for artificial microcompartmentation, cell analogue systems, micro-ecological studies, investigations on modulated morphogenesis, and for a bioanalogue molecular nanotechnology.

Segmented flow generation by chip reactors for highly parallelized cell cultivation

Micro system technology offers convenient tools for the production of handling devices for small liquid volumes which can be used in cell cultivation. Here, a modular system for the rapid generation of cell suspension aliquots is presented. The system is used to produce and analyze high numbers of well-separated culture volumes. Selected clones may be retrieved from the system. Therefore, the principle of segmented flow is applied. Portions of aqueous culture medium containing one cell or very small cell ensembles are separated from each other by a nonmiscible liquid like dodecane, tetradecane or mineral oil. In addition, the alkane separates the culture droplets from the innerside of the walls of chip channels and capillaries. This way, compatibility problems between cell wall surfaces and the chemical character of walls are excluded. The separated culture droplets are guided by micro flow transportation in different channel and chamber topologies. The whole system has the character of a serially operating cell processing system. The aliquot generation can be sped up to frequencies of about 30 Hz in each microchannel. That means, that about 10(5) individual cultural volumes can be produced per hour or about 2 million per day. The survival and the growth of microorganisms has been shown for model organisms as well as for organisms from a natural sample (soil).