Tailoring Superhydrophobic Properties of Organic Electrochemical Biosensor for Cancer Cell Culture Medium Identification

Conducting polymers are materials displaying high electrical conductivity, easy of fabrication, flexibility and biocompatibility, for this, they are routinely employed in organic electronics, printed electronics, and bioelectronics 1, 2, 3. Organic electrochemical transistors devices, based on the conductive polymer PEDOT:PSS, have been demonstrated in chemical and biological sensing: while accurate in determining the size of individual ions in solution4, similar devices break down if challenged with complex mixtures, due to the lack of spatial resolution. Here, we modified a conductive PEDOT:PSS polymer to include extra non-continuous scales in the device. This comprises super-hydrophobic SU8 pillars positioned on the substrate to form a non-periodic square lattice, in which the distance between the pillars smoothly transitions from the center to the periphery of the pattern 5. The pattern incorporates a finite number of micro-electrodes in a line that represent the active or sensitive spots of the device. The entire system is coated in cascade with a conductive PEDOT:PSS polymer and by a fluorocarbon polymer which assures the hydrophobicity of the device 6. A solution on a similar device would maintain a spherical shape as suspended in air. Due to its curvature, Marangoni convective flows develop within the volume of a drop of solution7. The competition between convection and diffusion will cause a spatial separation of biological species that would depend on the size and charge of the species in a solution. On realizing a time and space resolved measurement of the solution, the described device may operate the identification and separation of different species mingled up in a solution with high sensitivity, selectivity and reliability.Here we operate the identification of the "waste deposit" of cell culture medium upon interaction with circulating cell isolated form peripheral blood sampling of health, sub-clinical and colon cancer patients. The culture mediums were conditioned during a short-time cultivation of fourteen days performed as previously described (8). The unsupervised classification of the described datasets into defined groups with a small error suggests that the method may be used for the evaluation of the health status of patients even by not trained or minimally trained personnel, or for exploratory data analysis to find hidden patterns in data reflecting the ongoing patient assessment, which may both have major benefits for the national health care.