Towards an integrated device that utilizes adherent cells in a micro-free-flow electrophoresis chip to achieve separation and biosensing

We immobilized adherent human embryonic kidney (HEK) cells-which are able to trace adenosine triphosphate (ATP) -inside a microfluidic free-flow electrophoresis (mu FFE) chip in order to develop an integrated device combining separation and biosensing capabilities. HEK 293 cells loaded with fluorescent calcium indicators were used as a model system to enable the spatially and temporally resolved detection of ATP. The local position of a 20 mu M ATP stream was successfully visualized by these cells during free-flow electrophoresis, demonstrating the on-line detection capability of this technique towards native, unlabeled compounds.