Bioelectronic Monitoring of Monocyte-to-Macrophage Differentiation

Monocytes, a major player in the immune system responses, differentiate into macrophages under the influence of various environmental factors. Understanding the complex differentiation mechanism is crucial for the development and discovery of targeted therapies. However, conventional methods used are mainly end-point assays, often time-consuming and labor-intensive. Real-time and higher throughput monitoring of the differentiation process can enable dynamic testing of this process hence increasing the biological relevance. We have developed a microfabricated bioelectronic platform aiming to monitor M0 macrophage transition from suspension to adherent cells, indicative of their successful differentiation. Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), is used as the active electrode due to its considerably lower impedance compared to conventional metal electrodes rendering it more sensitive to monitor cells attachment on the electrode. PEDOT:PSS is patterned into a microfabricated gold electrode array while well-designed PDMS-based wells are placed atop to confine the cells on the PEDOT:PSS-coated electrode array. The differentiation of suspension THP-l monocytes to adherent M0 macrophages is monitored by measuring the changes in the electrochemical impedance spectroscopy spectra of the electrode at the different stages of cell transition. The device demonstrates sensitivity in detecting cell adhesion (hence THP-l differentiation) on the PEDOT:PSS electrode surfaces, where PEDOT:PSS provides a suitable environment for cell growth and differentiation while being electrically conducting for signal transduction. The developed bioelectronic platform, combining conducting polymer electrode arrays for sensitivity and microwells for cell confinement and higher throughput can be further used for various cell-based assays given its versatility and ease in fabrication and operation.