Electrode Selection for Electrostimulation and TEER Using ECSARA

Abstract

The TransEpithelial/Endothelial Electrical Resistance (TEER) of cells grown in the 24-well electroculture ware of an Electrical Cell Stimulation and Recoding Apparatus (ECSARA) shows well-to-well variation as potentially a function of the electrode material employed in stimulation-interrogation. Six electrode materials were studied; glassy carbon (GCE), graphitic carbon (GrC), titanium (Ti), platinized Type 304 stainless steel (PtSS), platinum (Pt100) and gold (Au). Each unmodified electrode was studied by multiple scan rate cyclic voltammetry (MSRCV) and by electrochemical impedance spectroscopy (EIS) with equivalent circuit analysis (EQCRTA) in PBS and in Fe(II)/Fe(III). MSRCV and Randles-Sevcik analysis of the bare electrodes produced an effective area correction factor γ* that rank-ordered the electrodes GrC = 1.58 > Pt = 1.40 > GCE = 0.94 > Au = 0.66 > PtSS = 0.11 > Ti = 0.01. Tandem EIS-EQCRTA produced R CT (Ω)/γ* of 1.20 × 10 2 and 5.60 × 10 8 for GrC and Ti, respectively and established these two electrode materials as the performance extremes. GrC and Ti were used as electrode materials in the 24-well electroculture ware of ECSARA. The coefficient of variation of the charging capacity extracted from CVs of GrC (22 wells, 10.05 mC) and Ti (22 wells, 1.75 mC) was 51.4 % and 54.6 % respectively, reflective of the difference in surface area. EIS-EQCRTA of GrC and Ti (21 wells) showed both electrodes to faithfully measure the solution resistance, R S , with CV of 54 % and 28 %, respectively, despite the lower charge transfer resistance, R CT , of GrC (R CT = 1.08 × 10 3 Ω, CV = 125 %) compared to Ti (R CT = 1.20 × 10 5 Ω, CV = 30 %). Overall, Ti electrodes were shown to be more appropriate for application in cell stimulation and TEER recording.

Electrically stimulated gene expression under exogenously applied electric fields

“…The Y -axis in the top and bottom panels represents the relative fold change in R’ CELL (top panel) and Q’ CELL (bottom panel), respectively, normalized to their respective values measured 1 h post cell seeding ( n = 3). (B) An equivalent circuit schematic of the R S (Q CELL R CELL ) (Q Ox R Ox ) (Q DL R CT ) model for the Titanium (Ti) electrode and its association with the cellular layer and the cell culture media EIS-EQCRT model parameters [Adapted from Abasi et al (2020b) ].…”

“…Isolating such interactions between EFs and its downstream influence on cellular processes requires precise engineering of the interrogation system. To facilitate electromics, a cell culture system to culture and monitor the cellular response to uniform electrical fields in real time, termed the electrical cell stimulation and recording apparatus (ECSARA), was previously designed, fabricated, tested, and reported ( Abasi et al, 2020a ; Abasi et al, 2020b ). The use of conventional 24-well cell culture plate format allows simultaneous, multiplexed investigations of gene expression under a uniform electric field orthogonal to the cell growth plane of trans-well cell culture inserts.…”

Real-time measurement of the trans-epithelial electrical resistance in an organ-on-a-chip during cell proliferation

“…7,[29][30][31] Different electrode materials, electrode patterns, and measurement temperatures have been explored to improve the accuracy of TEER measurement. [32][33][34][35] However, few have tried to reconstruct the circuit models. The difference in the area coverage limit of cells grown in different culture environments should be considered in optimizing the transmembrane impedance measurement model.…”