Agostino Romeo

Irreversible evolution of eumelanin redox states detected by an organic electrochemical transistor: en route to bioelectronics and biosensing

Organic electrochemical transistors (OECTs) are currently emerging as powerful tools for biosensing, bioelectronics and nanomedical applications owing to their ability to operate under liquid phase conditions optimally integrating electronic and biological systems. Herein we disclose the unique potential of OECTs for detecting and investigating the electrical properties of insoluble eumelanin biopolymers. Gate current measurements on fine aqueous suspensions of a synthetic eumelanin sample from 5,6-dihydroxyindole (DHI) revealed a well detectable hysteretic response similar to that of the pure monomer in solution, with the formal concentration of the polymer as low as 10-6 M. Induction of the gate current would reflect electron transfer from solid eumelanin to the Pt-electrode sustained by redox active catechol/quinone components of the polymer. A gradual decrease in gate current and areas subtended by hysteretic loops were observed over 5 cycles both in the eumelanin- and DHI-based devices, suggesting evolution of the polymer from a far-from-the-equilibrium redox state toward a more stable electronic arrangement promoted by redox exchange with the gate electrode. OECTs are thus proposed as valuable tools for the efficient heterogeneous-phase sensing of eumelanins and to gauge their peculiar electrical and redox behaviour.

Flexible sensors for biomedical technology

Flexible sensing devices have gained a great deal of attention among the scientific community in recent years. The application of flexible sensors spans over several fields, including medicine, industrial automation, robotics, security, and human-machine interfacing. In particular, non-invasive health-monitoring devices are expected to play a key role in the improvement of patient life and in reducing costs associated with clinical and biomedical diagnostic procedures. Here, we focus on recent advances achieved in flexible devices applied on the human skin for biomedical and healthcare purposes.

A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC) slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

Drug-induced cellular death dynamics monitored by a highly sensitive organic electrochemical system

We propose and demonstrate a sensitive diagnostic device based on an Organic Electrochemical Transistor (OECT) for direct in-vitro monitoring cell death. The system efficiently monitors cell death dynamics, being able to detect signals related to specific death mechanisms, namely necrosis or early/late apoptosis, demonstrating a reproducible correlation between the OECT electrical response and the trends of standard cell death assays. The innovative design of the Twell-OECT system has been modeled to better correlate electrical signals with cell death dynamics. To qualify the device, we used a human lung adenocarcinoma cell line (A549) that was cultivated on the micro-porous membrane of a Transwell (Twell) support, and exposed to the anticancer drug doxorubicin. Time-dependent and dose-dependent dynamics of A549 cells exposed to doxorubicin are evaluated by monitoring cell death upon exposure to a range of doses and times that fully covers the protocols used in cancer treatment. The demonstrated ability to directly monitor cell stress and death dynamics upon drug exposure using simple electronic devices and, possibly, achieving selectivity to different cell dynamics is of great interest for several application fields, including toxicology, pharmacology, and therapeutics.

SiC Biosensing and Electrochemical Sensing: State of the Art and Perspectives

Abstract We present an extensive overview of SiC biomedical applications, focusing in particular on SiC-based electrochemical biosensors, a very promising field of recent developments and perspectives. The properties, performance, and potential role of SiC are discussed in comparison with the most successful and popular electrochemically active organic semiconductor, that is, poly(3,4-ethylenedioxythiophene): poly(styrene sulfonic acid) (PEDOT:PSS), the most used in bioelectronics. To this end, the state of the art of SiC-based devices is first outlined, discussing the most advanced applications in medicine, diagnostics, and prosthetics. Then, electrochemical biosensors made of SiC as the active and sensing material are introduced and reviewed in detail. Because of the growing importance of organic electrochemical transistors (OECTs) in the organic bioelectronics arena, a whole section is dedicated to comparing the general features and performance of SiC and OECT sensors based on PEDOT:PSS. Finally, the last section is devoted to the perspective and viability of SiC-based ion-sensitive field effect transistors (ISFET) for the efficient and demanding application of ionic species sensing and offers suggestions on potential sensor architectures.