Final Report: Development of microreactors for biopharmaceutical applications / Open capillary wave micro-reactor for biopharmaceutical screening applications

The objective of the project was to develop a parallelized droplet-based microbioreactor (MBR) with a high sensor implementation for cell-based assays and biopharmaceutical applications. A capillary wave microbioreactor (cwMBR, reaction volume 7 μL) in monolithic design was developed, fabricated and comprehensively characterized using femtosecond laser direct writing and chemical etching techniques in fused silica. A suitable mixing technique based on vertical oscillation was designed for the small volume of liquid. The induced vertical oscillation leads to an oscillation of the liquid surface corresponding to the frequency and deflection. On this basis, the resonant frequency of the liquid was identified as the decisive factor for the mixing performance. By applying this vertical oscillation method, excellent mixing times < 2 s and exceptionally high volumetric mass transfer coefficients of 340 h-1 were achieved. Furthermore, the influence of different oscillation settings and the resulting effects on the cell growth of Escherichia coli with different vibration settings were investigated. In further work, the cwMBR array was extended to a platform consisting of nine cwMBRs with an automated liquid dosing system and equipped with extensive online sensor technology (including liquid control, resonance monitoring, pH value, dissolved oxygen and glucose concentration, optical density and impedance). As application examples, phagogram lysis kinetics and live/dead analyses of mammalian cell cultures were performed in the cwMBR platform. Phagograms are sensitivity tests of bacteria to bacteriophages, which are essential for the implementation of phage therapies to combat multi-resistant bacteria. In order to increase throughput, reduce laboratory workload and increase reproducibility, the automation of the developed cwMBR platform for phagograms in phage therapy was advanced. The applicability of the platform was demonstrated using the example of recording lysis kinetics in phagograms with E. coli and automated phage addition. The results show a clear lysis of the bacteria by the phages and thus confirm the applicability of automated phagogram generation in the highly parallelizable cwMBR platform. An automated, parallelized screening tool based on a fully sensor-equipped cwMBR platform is now available. Only minor changes to the platform are required to perform fully automated high-throughput phagograms in the future. These include: - the expansion of the nanodispenser unit for additional phage suspensions and a device for flexible switching between different phage solutions, water for liquid level control, detergents or disinfectants to avoid cross-contamination, and - the significant increase in parallelization in a second dimension in order to further increase the number of parallel experiments for additional bioprocess engineering applications.