Smart Carbon Scaffolds for Electrochemical Monitoring of Cell Cultures

In bioelectrochemical applications, cells are typically incubated on 2D electrodes. The major limitation of this approach is that planar electrode geometry poorly mimics the natural environment of the cells. 3D polymer scaffolds have been developed to provide a more realistic environment for the cells but these structures usually lack integrated sensor functionality to perform in situ measurements in the 3D cell culture. Here, we address these limitations and demonstrate the in situ electrochemical analysis of alkaline phosphatase (ALP) activity in a 3D bone tissue model with integrated electrochemical sensing using 3D pyrolytic carbon microelectrodes. Furthermore, we integrate pyrolytic carbon electrodes on an optical fibre to obtain a leaky optoelectrical fibre (LOEF). With the LOEF serving as a smart scaffold, we demonstrate the combined optical stimulation of optogenetially modified human neural stem cells (hNSC) and electrochemical recording of the resulting release of the neurotransmitter dopamine.