ABSTRACT
Electrodes coated with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) have been employed to measure the integrity of cellular barriers. However, a systematic experimental study of the correlation between tissue integrity and impedance of the sensing device has not yet been conducted. Using impedance spectroscopy, how the impedance ratio of the biological tissue to the recording device affects the recording ability of the latter is investigated. PEDOT:PSS-coated electrodes of various dimensions are employed and the effect of their size to their sensing efficiency is examined. The biotic/abiotic ensemble is modeled with a simple equivalent circuit and an analytical expression of the total impedance as a function of frequency is extracted. The results reveal a critical impedance ratio of the biological tissue to the sensor which allows for efficient sensing of the tissue integrity. This work provides the ground rules for improved impedance-based biosensors with optimized sensitivity.
Subject(s)
Biosensing Techniques/methods , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Dielectric Spectroscopy/methods , Polymers/chemistry , Polystyrenes/chemistry , Electric Impedance , ElectrodesABSTRACT
The integrity of CaCo-2 cell barriers is investigated by organic electrochemical transistors (OECTs) in a current-driven configuration. Ion transport through cellular barriers via the paracellular pathway is modulated by tight junctions between adjacent cells. Rupturing its integrity by H2 O2 is monitored by the change of the output voltage in the transfer characteristics. It is demonstrated that by operating the OECT in a current-driven configuration, the sensitive and temporal resolution for monitoring the cell barrier integrity is strongly enhanced as compared to the OECT transient response measurement. As a result, current-driven OECTs are useful tools to assess dynamic and critical changes in tight junctions, relevant for clinical applications as drug targeting and screening.
