Biocompatibility and Long-Term Stability of DNA-Based Organic Mixed Conductors for Bioelectronics

In the field of bioelectronics, designing novel organic mixed ionic-electronic conductors (OMIECs) is crucial to overcome the limitations in terms of biocompatibility and long-term stability. Polymeric OMIECs are reported for their potential applications in implantable devices to record and stimulate biological signals. Deoxyribonucleic acid (DNA) templated PEDOT and polypyrrole are synthesized via oxidative chemical polymerization. The biocompatibility and long-term chemical stability of conductive composites PEDOT:DNA and PPy:DNA are evaluated and compared to PEDOT:PSS. To examine in vitro cytotoxicity, NIH 3T3 cells are cultured on thin-films of PEDOT:PSS and DNA-based biocomposites. The visual determination of cell morphology and adhesion are carried out by fluorescent optical microscopy and atomic force microscopy (AFM) imaging. The acute and long-term cell viability is performed by using flow cytometry. After 96 h of incubation, the cells maintain over 80% viability, retaining their morphology and adhesion properties similar to control cells on plastic or glass samples. This indicates that all tested samples demonstrate high biocompatibility. The material stability of PEDOT:DNA and PPy:DNA is investigated by integrating the materials into organic electrochemical transistors (OECTs). The results confirm an efficient ion-to-electron transduction in OECTs and long-term chemical stability after storing the materials for up to 5 years.