Conducting Polymers as Novel Tools for Biosensing and Tissue Engineering

The field of Bioelectronics deals with the integration of electronics and biology, and possesses a tremendous potential regarding the improvement of the quality of life of millions of people. Thanks to their favorable properties, conjugated polymers have proven to be very suitable materials for the bridging of such diverse worlds. In particular, poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), or PEDOT:PSS, is nowadays considered a benchmark material for bioelectronics applications. The aim of the present work is to give a detailed characterization of the physical and electrochemical properties of PEDOT:PSS thin films, and to prove the potentialities of this material both for the sensing of bioanalytes, through the development of innovative electrochemical sensors, and for tissue engineering applications, through the development of redox-active substrates that can control the replication of living cells. In this work, the development of all PEDOT:PSS-based organic electrochemical transistors (OECTs) is presented. The sensing efficiency of these devices was optimized in terms of sensitivity and limit of detection (LOD) through the investigation of the effect of device geometry, thickness, and operating voltages. An electrochemical characterization of these devices was carried out as well, in order to clarify the processes involved in the device operation. Furthermore, the operation of these devices as electrochemical sensors was tested on several analytes, obtaining in most cases a performance suitable for real applications. The development and characterization of a different kind of devices realized using the same material, redox-active substrates for applications in tissue engineering, is then presented. The effect of a change in the redox state of these PEDOT:PSS films on cell growth is assessed using two cell lines, human dermal fibroblasts (hDF) and human tumoral glioblastoma multiforme cells (T98G), finding that the cell proliferation rate has a clear dependence on the electrochemical state of its substrate.