Fig. 3: Impact of chemical functionalization on seal resistance.
From: Impedance spectroscopy of the cell/nanovolcano interface enables optimization for electrophysiology
a Optical micrograph of human embryonic kidney cells (HEK) 24 h after plating on bare glass substrate shows elongated features with little spreading over the substrate. b In comparison, cells plated on glass substrate functionalized with poly-D-lysine (PDL) and collagen assume a flatter cell body configuration by spreading more on the substrate due to improved adhesion. c Impedance spectra displayed as a Bode plot of the magnitude (solid line) and phase (dashed line) for cells plated on bare and PDL + collagen-functionalized substrates. The impedance spectrum acquired from nanovolcanoes not covered by a cell is displayed as a control. The impedance magnitude is represented by the mean of the sample of cells interrogated ± one time the sample standard deviation represented by the colored area. Sealing resistances are obtained from the resistive portion of the spectra characterized by a minimum in the impedance phase (phase closest to 0° marked by colored arrows; see text for detail). d Comparison of seal resistances for samples of HEK cells cultured on bare glass (n = 17), PDL (n = 20) and PDL + collagen (n = 20). p-values correspond to a two-sided Mann‒Whitney U-test
