Light‐Addressable Ion Sensing for Real‐Time Monitoring of Extracellular Potassium

Abstract

We report here on al ight addressable potassium (K + )s ensor where light illumination of as emiconducting silicon electrode substrate results in alocalized activation of the faradaic electrochemistry at the illuminated spot. This allows one,b ye lectrochemical control, to oxidize surface bound ferrocene moieties that in turn trigger K + transfer from the overlaid K + -selective film to the solution phase.T he resulting voltammetric response is shown to be K + -selective,where peak position is ad irect function of K + activity at the surface of electrode.T his concept was used to measure extracellular K + concentration changes by stimulating living breast cancer cells. The associated decrease of intracellular K + level was confirmed with af luorescent K + indicator.I nc ontrast to light addressable potentiometry,the approach introduced here relies on dynamic electrochemistry and may be performed in tandem with other electrochemical analysis when studying biological events on the electrode.

Manipulation of Transmembrane Transport by Synthetic K+ Ionophore Depsipeptides and Its Implications in Glucose‐Stimulated Insulin Secretion in β‐Cells

“…We also performed cellular localization studies in INS1E cells with the fluorescently tagged cereulide JG121 to confirmt hat the cyclic depsipeptides are cell-penetrating compounds, an important feature when studying biological eventsm ediated by K + ioni nteractions. [41][42][43] The INS1E cells, culturedu nder standardc onditions, were incubated with 2.5 and 25 ng mL À1 of the probe from an initial solution in DMSO. The nucleus of fixed cells was stained with DAPI (4',6-diamino-2-phenylindole).…”

Monitoring the heterogeneity in single cell responses to drugs using electrochemical impedance and electrochemical noise

“…27,29 We have also shown that this technique can be used to release rare single cells captured on an unpatterned surface, 3 and the detection of ion release from single cells, combined with uorescence microscopy can be used to show how the cells respond to drug treatment. 30 Herein we further show it is possible to perform conventional impedance measurements on single cells that are located anywhere on the silicon electrode surface. This is achieved by illuminate the region of a single cell and monitoring changes in electrochemical impedance as the cell phenotype changes.…”

Recent Developments of High-Resolution Chemical Imaging Systems Based on Light-Addressable Potentiometric Sensors (LAPSs)

“…In order to reduce the recombination of photocarriers and improve spatial resolution, the silicon bulk can be replaced with thin silicon films (thinned silicon substrate [38,39,40], silicon on insulator (SOI) [18], amorphous silicon (a-Si) [41,42,43,44] and silicon on sapphire (SOS) [45,46]) or other semiconductor thin layers deposited on transparent substrates (GaAs [47], GaN [48], In-Ga-Zn oxide (IGZO) [49] and indium tin oxide (ITO) [50]). The sensing material such as Si 3 N 4 [1,28,38,39,51], Al 2 O 3 [52,53,54], Ta 2 O 5 [51], HfO 2 [55,56,57], NbO x [40,58,59], SnO x [60], self-assembled organic monolayer (SAM) [61,62] and nanofibers [63,64] can be used for pH sensing. Other chemical species can be also detected by modifying the sensing surface with appropriate materials.…”