Electrochemical monitoring of cell behaviour in vitro: A new technology

Abstract

This article describes a novel electrochemical technique for the real-time monitoring of changes in the behaviour of adherent human cells in vitro: i.e., a biosensor that combines a biological recognition mechanism with a physical transduction technique, described collectively as Oncoprobe. Confluent viable cells adherent to gold electrodes (sensors) modify the extracellular microenvironment at the cell:sensor interface to produce a change in the electrochemical potential compared to that measured in the absence of cells. The potential was measured as an open circuit potential (OCP) with respect to a saturated calomel reference in the bulk culture medium. Typical OCP values for confluent cultures of human breast carcinoma cells, 8701-BC, approximated -100 mV compared with cell-free values of approximately -15 mV. The OCP for 8701-BC cells was modified in response to temperature changes over the range 32 to 40 degrees C and also to treatments with phytohemagglutinin (PHA, 25 microg/mL), cycloheximide (30 microM) and interleukin-1 beta (IL-1, 0.5 ng/mL) over 24 h. Cultures of synovial fibroblasts also responded to the same treatments with similar responses, producing negative shifts in the OCP signal with PHA and IL-I, but a positive shift in OCP signal with cycloheximide, all relative to the untreated control cultures. From experimental data and theoretical considerations it is proposed that the cell-derived signals are mixed electrode potentials reflecting a "conditioned," more reducing environment at the cell:sensor interface. Only viable cells caused a negative shift in the OCP signal, this being lost when cells were rendered nonviable by formalin exposure. This technology appears unique in its ability to passively "listen in" on cell surface activities, suggesting numerous applications in the fields of drug discovery, chemotherapy, and cell behaviour.

A Multiwell Electrochemical Biosensor for Real-Time Monitoring of the Behavioural Changes of Cells in Vitro

“…Demonstrated in Figure 3 by the adherence of human breast carcinoma cells (8701-BC) to the gold sensor as judged by scanning electron microscopy, 24 h after seeding; such attachment of viable cells being essential for the generation of an electrochemical signal (OCP). These cells have previously been shown to adhere to solid gold sensors [1] and successfully attached to the screen printed conductive ink gold sensors employed here.…”

“…Progression from an independent single well prototype unit to a disposable multiwell device; miniaturisation, which has allowed the number of cells and amount of media required per assay to be significantly reduced and the screen printing manufacturing process employed confers a high degree of reproducibility and reliability. Temperature and pH, factors we have previously shown to be important to the OCP signal obtained from sensors, have benefitted from greater stability due to operation within the controlled environment of a CO 2 incubator [1]. In addition to the hardware developments, the polarity of the OCP displayed has been reversed from our earlier work [1,2], i.e ., a more positive potential represents a more reducing state, whereas a more negative potential represents a more oxidising state.…”

“…We have previously reported the principles of an electrochemical biosensor, ‘Oncoprobe’, for passively recording the Electrochemical open circuit potential (OCP) of confluent cell monolayers on gold sensors in vitro and its application in anticancer drug testing [1–3]. The technology operates by monitoring the electrochemical potential generated at the microenvironment of the cell:sensor interface, measured relative to a reference electrode located in the bulk culture medium.…”

A new disposable electrode for electrochemical study of leukemia K562 cells and anticancer drug sensitivity test

“…Many kinds of methods, such as electrochemical impedance spectroscopy (Cao et al, 2012;Faenza et al, 2012;Giaever and Keese, 1993), scanning electrochemical microscopy (Allen et al, 2006;Kaya et al, 2003;Torisawa et al, 2003), electric cell-substrate impedance sensing (Arndt et al, 2004;Xiao et al, 2002;Xiao and Luong, 2003), open circuit potential at the cell/sensor interface (Woolley et al, 2002), and electron transfer at electroactive centers in cells (El-Said et al, 2009;Li et al, 1999;Wu et al, 2009), have been approved to be effective to provide nonmorphological observation for following cell health state and establishing effective in vitro anticancer drug sensitivity tests (Kanwal et al, 2013;Wu D.M. et al, 2011;Zhang D.D.…”

Fabrication of Stem Cell Chip with Peptide Nanopatterned Layer to Detect Cytotoxicity of Environmental Toxicants

“…The redox current achieved from cancer cells was found to have negative linearity with the concentrations of toxic materials that directly represented the cell viability. 14 15 polymer, 16 and alginate bead. 17 However, cell chip composed of human neural stem cells have not been reported due to the difficulties for maintaining its stemness and cell attachment on the artificial electrode surface, which is critical for sensitive detection of cell viability electrochemically.…”