A continuous flow microreactor was used for the synthesis of gold nanoparticles (5 to 50 nm) directly from a gold salt (HAuCl(4)) and a reducing agent (ascorbic acid). Experimental parameters were optimized to obtain narrow size distributions, which were at average two times narrower than those obtained in a conventional synthesis. Additionally, two approaches, i.e., elevation of pH during reaction and hydrophobization of internal reactor surfaces were tested to suppress reactor fouling.

Flow-through chip thermocyclers can be used in miniaturized rapid polymerase chain reaction (PCR) despite their high surface to volume ratio of samples. We demonstrated that a thermocycler made of silicon and glass chips and containing thin film transducers for heating and temperature control can be adapted to the amplification of various DNA templates of different sources and properties. Therefore, the concept of serial flow in a liquid/liquid two-phase system was combined with a surface management of inner side walls of the microchannel and an adaptation of PCR mixture composition. In addition, the process temperatures and the flow rates were optimized. Thus, a synthetic template originating from investigations on nucleic acid evolution with 106 base pairs [cooperative amplification of templates by cross hybridization (CATCH)], a house keeping gene with 379 base pairs [glutaraldehyde 3-phosphate dehydrogenase (GAPDH)] and a zinc finger protein relevant in human pathogenesis with 700 base pairs [Myc-interacting zinc finger protein-1, knock-out (Miz1-KO)] were amplified successfully. In all three cases the selectivity of priming and amplification could be shown by gel electrophoresis. The typical amplification time was 1 min per temperature cycle. So, the typical residence time of a sample volume inside the 25 cycle device amounts to less then half an hour. The energy consumption of the PCR chip for a 35 min PCR process amounts to less than 0.012 kW h.

The high speed production of fluid segments for the highly parallelized cultivation of monoclonal cell populations was carried out by the use of microchip segmentor modules. Aqueous fluid segments, embedded in a non-miscible carrier liquid, were produced with frequencies up to 30 s(-1) and showed a high homogeneity in size. This corresponds with the production of about 2.5 million samples per day. The segment volumes can be adapted between about 4 nl and 100 nl. The typical segment size for cultivation experiments is in the range between 40 nl and 80 nl. Nutrient medium can be applied instead of pure water. It is possible to aliquot a cell suspension in such a way that most of the aqueous fluid segments contain only one cell. In model experiments with four microbial species chip-produced aliquots of 60 nl, each containing one or a few cells, were incubated in Teflon capillary tubes. Rapid growth of the microcultures was observed. Cell densities were found to be as high as in conventional shake flask cultures.

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Surface-enhanced Raman scattering (SERS) is a promising platform for particle-based sensor signaling, and droplet-based microfluidic systems are particularly advantageous for control of the size and composition of micro- and nanoparticles. For controlled sensing application, a high homogeneity of the sensor particles is a key requirement, and the particles with functional properties demand for the preparation in a minimum number of synthesis steps. Frequently used coflow and flow focusing arrangements, however, produce the microparticles of only larger size. To address such concern for downscaling of particle size, which is crucial for strong sensing outcome, we have used a peculiar micro cross-flow arrangement here for generating the polymer microparticles of broad size range between 30 and 600 μm along with in situ embedded silver nanoparticles. Embedded silver acts as nuclei for additional silver enforcement via silver-catalyzed silver deposition in order to realize the composite microparticles for SERS sensing. The homogeneous size and spatial distribution of silver nanoparticles inside the matrix and enforcement over the surface together with controlled pore size provides a high and homogeneous loading of polymer composite sensor. Moreover, different parameters such as analytes concentration and particles size have been studied here for SERS sensing application of biochemical molecules (amino acids and vitamins). Overall, the platform for size-tuned droplets generation, synthesis of composite microparticles, mechanism for synchronized photopolymerization-photoreduction, tuned silver enforcement, and the impacts of different analytes on differently composed microparticles are systematically investigated in this paper.

Potential biomedical applications such as controlled delivery with sustained drug release profile demand for multifunctional polymeric particles of precise chemical composition and with welldefined physicochemical properties. The real challenge is to obtain the reproducible and homogeneous nanoparticles in a minimum number of preparation steps. Here, single-step nanoarchitectures of soft surface layered copolymer nanoparticles with a regular tuning in the size via micro flow-through assisted synthesis are reported. Interfacial copolymerization induces the controlled compartmentalization where a hydrophobic core adopts spherical shape in order to minimize the surface energy and simultaneously shelter in the hydrophilic shelllike surface layer. Surface layer can swell in the aqueous medium and allow controlled entrapping of functional hydrophobic nanoparticles in the hydrophilic interior via electrostatic interaction which can be particularly interesting for combined fluorescence activity. Furthermore, the nanoarchitecture of size and concentration controlled polymer-metal nanoassembly particles can be implemented as an ideal surface-enhanced Raman scattering substrate for detection of the trace amounts of various analytes.

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.