Bipolar electrochemical growth of conductive microwires for cancer spheroid integration: A step forward in conductive biological circuitry

The field of bioelectronics is developing exponentially. There is now a drive to interface electronics with biology for the development of new technologies to improve our understanding of electrical forces in biology. This builds on our recently published work in which we show wireless electrochemistry could be used to grow bioelectronic functional circuitry in 2 dimensional (2D) cell layers. To date our ability to merge electronics with biology which is 3 dimentional (3D) is limited. In this study, we aimed to further develop the wireless electrochemical approach for the self-assembly of microwires in-situ with custom-designed and fabricated 3D cancer spheroids. Thereby, creating interlinked bioelectronic circuitry with cancer spheroids. We demonstrate that a direct current was needed to stimulate the growth of conductive microwires in the presence of cell spheroids. Microwire growth was successful when using 50 V (0.5 kV/cm) of DC applied to a single spheroid of approximately 800 m in diameter but could not be achieved with alternating currents. This represents the first proof of the concept of using wireless electrochemistry to grow conductive structures with 3D mammalian cell spheroids.