Gregor Schlingloff

Microlenses as Amplification for CCD-Based Detection Devices for Screening Applications in Biology, Biochemistry, and Chemistry.

We describe the use of microlenses as amplification for CCD-based detection devices. The possible amplification of a signal in areaction chamber of a nanoplate is estimated with a first-order approximation. This value was proved with a commercially available microlens and with a specially constructed microlens array made of glass hemispheres. Possible applications of this approach to amplification are given.

Mimicking the biological world: Methods for the 3D structuring of artificial cellular environments

Combining modern methods in microsystem technology with the latest advancements in the life sciences, namely those in tissue engineering and advanced cell culturing, is promoting the development of a promising toolbox for modeling biological systems. The core problem to solve using this toolbox is the design of 3D artificial cellular environments, both in fluidic systems and on solid substrates. The construction of 3D biological fluidic environments involves the use of microfluidic devices where fluid direction and behavior can be tightly regulated in a geometrically constrained environment for advanced cell cultivation. This is used in modern cultivation devices, such as bioreactors and multicompartment systems, including systems with integrated multielectrode arrays in both 2D and 3D. The construction of 3D cell cultures on substrates involves various fabrication techniques that use different polymers and biopolymers processed by micromachining, chemical pattern guided cell cultivation, photopolymerization, and organ printing methods. These methods together have the potential to create an artificial system with the complete hierarchical, geometrical, and functional organization found in an actual biological system. In this review, we describe representative developments in this research area and the fusion of formerly unrelated disciplines that are generating new beneficial applications in life sciences.

Microbioreactor design for 3-D cell cultivation to create a pharmacological screening system

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.

Single bead parallel synthesis and screening

Microstructured silicon wafers were employed as miniaturizedsolid-phase reaction vessels as well as miniaturized microtiter plates. Employing piezoelectric drop-on-demand liquidjets, a combinatorial library of 256 Peptides was synthesizedon single beads. The synthesis protocol was associated to thelocation in the silicon nano-well arrangement. Products werephotolytically cleaved in the same well that was used forsynthesis and subsequently interrogated for thrombin inhibitionin a homogeneous competition assay. The assay procedure wasbased on drop-on-demand liquid delivery and laser inducedfluorescence imaging. The novel format proved useful for theintegration of both synthesis and screening into one platform,a prerequisite for an iterative, evolutionary approach towardsdrug discovery.

Robotic alliance of miniaturized synthesis and screening: A case study for the identification of histone deacetylase inhibitors

Modern drug development in preclinical pharmaceutics is based on two fundamental processes: library synthesis and screening. Usually, synthesis and screening are separated processes that need a compound storage facility as an interface. Unfortunately, compound storage is a complex process and can lead to compound degradation. For this reason, the chemical identities of found screening hits have to be reanalyzed after the biological screening to be confident. Here, we present a robotic facility that combines solid‐phase one‐bead one‐compound synthesis and screening in a unified workflow using miniaturized formats for on‐demand library synthesis. The technical proof of concept was achieved by an exemplary run that combines the solid‐phase synthesis of a hydroxamate library and the subsequent biological screening for different histone deacetylase activities using a homogeneous fluorescence assay. Compound storage and related processing steps were thus omitted in this way. Technical concepts for all necessary steps and their robotic solutions for the integration of both synthesis and screening processes in one overall workflow are shown in detail. As a result, different enzyme selective histone deacetylase inhibitors were identified using the integrated workflow.

Biochemical Synthesis in Microstructured Silicon Wafer

In biotechnics microsystems have been introduced primarily for analytical purpose in the past few years. Recently miniaturised microtiterplates, so called nanotiterplates, as efficient tools in screening have been discussed. In a case study we demonstrate the application of cell-free translation or transcription/translation and nucleic acid amplification in such nanotiterplates. The results show the potential range of applications of nanotiterplates for biotechnology even for biochemical systems, which have not been discussed as miniaturisable in screening.