We describe a multi-purpose platform for the three-dimensional cultivation of tissues. The device is composed of polymer chips featuring a microstructured area of 1-2 cm(2). The chip is constructed either as a grid of micro-containers measuring 120-300 x 300 x 300 microm (h x l x w), or as an array of round recesses (300 microm diameter, 300 microm deep). The micro-containers may be separately equipped with addressable 3D-micro-electrodes, which allow for electrical stimulation of excitable cells and on-site measurements of electrochemically accessible parameters. The system is applicable for the cultivation of high cell densities of up to 8 x 10(6) cells and, because of the rectangular grid layout, allows the automated microscopical analysis of cultivated cells. More than 1000 micro-containers enable the parallel analysis of different parameters under superfusion/perfusion conditions. Using different polymer chips in combination with various types of bioreactors we demonstrated the principal suitability of the chip-based bioreactor for tissue culture applications. Primary and established cell lines have been successfully cultivated and analysed for functional properties. When cells were cultured in non-perfused chips, over time a considerable degree of apoptosis could be observed indicating the need for an active perfusion. The system presented here has also been applied for the differentiation analysis of pluripotent embryonic stem cells and may be suitable for the analysis of the stem cell niche.

A biocompatible cell culture environment that enables continued existence of three dimensionally aggregated cells in a polycarbonate-based scaffold structure was developed. A micro structured polymeric scaffold allows perfusion of cells due to a microporous structure generated by ion track etching and micro thermoforming. Biocompatibility and sterilizability was approved for the whole system. As oxygenation and mass transport within a closed system is most relevant for 3-D cell culture, two approaches of pumping systems were tested. The human hepatocarcinoma cell line HepG2 was used to examine basic cytological parameters in response to the enviroment. Our data indicate that an actively perfused 3-D cell culture induces a more differentiated phenotype in HepG2 cells than the 2-D setup. Thus, our results provide further support to the theory that 3-D-cultivated cells display a non-proliferative behavior. In this respect, 3-D cultures resemble in vivo conditions more closely. Microreactors are widely applied for organic syntheses, but can also be used for screening applications in drug discovery and medical research. The bioreactor versions presented here were equipped with active fluidic components.

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1Applications of nanotechnology and microtechnology lead to a field which could be called nanosystems integration. The next step is the development of nanobiotechnological systems, which could reflect the hierarchical organization of biological systems that utilise scales and laws of nature on all metric scales. As one example of such systems we present the design and construction of a new class of micro bioreactors. It has been shown that 3D culture systems reveal the in vivo situation much better than the cultivation of 2D one cell type alone. For this purpose we have to construct and arrange fluidic devices and a cell-biological environment in such a way, that living cells can survive in a three-dimensional, organ-like structure, enabled by technical devices. Such organ-like cell structures may lead to new ways in medicinal chemistry for the determination of ADME/Tox (absorption-distribution-metabolism-excretion and toxicity) properties of potential drugs. One part of the construction principle is the integration of sensors, preferable novel AlGaN/GaN nanosensors. The latter nanosensors offer the possibility to estimate reactions of cells attached to the sensor surface non-destructively and label-free. These sensors are highly sensitive and biocompatible to cells. Furthermore, they are transparent to enable microscopic and other optical observations of the cells. In an advanced version the sensor is to be integrated to give a better insight into cellular processes of the cells that are cultivated in such micro bioreactors.Keywords: Nanobiotechnology / micro-nanointegration / nanosensors / AlGaN-sensors / microfluidics / assays / advanced cell culture / Die Aufgabe mikro-und nanochtechnologisch hergestellte Funktionselemente zu ganzen Systemen bzw. zu makroskopischen Systemen zu assemblieren, hat zu einem Gebiet geführt, dass man NanoSystemintegration oder auch Mikro-Nanointegration nennen kann. Im Bereich der Nanobiotechnologie führt diese Entwicklung zu Systemen, die die hierarchische Organisation der biologischen Systeme nachbildet, die auf allen geometrischen Skalen von der Nano-über die Mikro-bis zur Makroebene präsent ist bzw. die dort wirkenden Naturgesetze nutzbar macht. Als ein Beispiel stellen wir eine neue Klasse von Mikrobioreaktoren vor. Es konnte gezeigt werden, dass 3D Zellkultursysteme die in vivo Situation wesentlich besser darstellen als 2 dimensionale Zellkultursysteme. Für diesen Zweck müssen wir mikrofluidische Systeme und eine zellbiologische Umgebung so konstruieren, dass lebende Zellen in einer dreidimensionalen, organartigen Struktur, die durch technische Baugruppen gebildet wird, überleben können. Solche organ-ähnlichen Zellverbände können zu neuen Methoden in der medizinischen Wirkstoffforschung führen, um z. B. ADME/Tox Eigenschaften zu bestimmen. Ein Teil der Konstruktion bezieht sich auf die Integration von Sensoren, vorzugsweise von AlGaN-Nanosensoren. Die letzteren ermöglichen es adhärente Zellen nicht destruktiv bzw. labelfrei zu untersuchen. Diese Sensoren sind hoch sensitiv un...

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