Highly integrated chip for continuous chemical synthesis, purification and inline biosensoric monitoring of biological activity on stem cell-derived 3D cardiomyocyte cultures.

Miniaturization and development of lab-on-a-chip (LOC) devices are a fast-evolving research field. While single processes e.g. pharmacological compound testing on cells and organoids, diagnostic applications, chemical synthesis or on-chip analytics are widely developed and in use, the integration of multi-step processes such as chemical synthesis, product separation and purification in combination with biological activity monitoring of synthesis products in compact LOC devices is poorly realized. Especially the integration of label-free, biosensoric analysis techniques is still a bottleneck. In this context, we developed an integrated microfluidic chip that combines an organic on-chip synthesis with subsequent continuous product purification and solvent-exchange by micro free flow electrophoresis (μFFE), followed by re-buffering to physiological conditions and finally, the biosensoric detection of biological activity on 3D cultures. As a proof of concept, the synthesis of the cardioactive drug propranolol from its precursor was chosen and successfully established in a continuous microfluidic setup. For sensitive detection of bioactivity, human stem cell-derived cardiomyocyte 3D cultures were used. The integration of microcavity microelectrode arrays, combined with impedance spectroscopy enabled label-free, non-invasive, real-time monitoring of propranolol isolation and purification as well as the quantification of the negative chronotropic effect of propranolol. The organoids show the typical negative chronotropic effect of propranolol in the μM range. Taken together, the entire process chain including chemical synthesis, purification, and inline monitoring of biological activity on a single LOC device, was successfully demonstrated.