TY - JOUR

T1 - Monitoring cellular stress responses using integrated high-frequency impedance spectroscopy and time-resolved ELISA

AU - Charwat, Verena

AU - Joksch, Martin

AU - Sticker, Drago

AU - Purtscher, Michaela

AU - Rothbauer, Mario

AU - Ertl, Peter

PY - 2014/10/21

Y1 - 2014/10/21

N2 - We have developed a lab-on-a-chip system for continuous and non-invasive monitoring of microfluidic cell cultures using integrated high-frequency contactless impedance spectroscopy. Electrically insulated microfabricated interdigitated electrode structures were embedded into four individually addressable microchambers to reliably and reproducibly detect cell-substrate interactions, cell viability and metabolic activity. While silicon nitride passivated sensor substrates provided a homogeneous cell culture surface that minimized cell orientation along interdigitated electrode structures, the application of high-frequency AC fields reduced the impact of the 300 nm thick passivation layer on sensor sensitivity. The additional implementation of multivariate data analysis methods such as partial least square (PLS) for high-frequency impedance spectra provided unambiguous information on intracellular pathway activation, up and down-regulation of protein synthesis as well as global cellular stress responses. A comparative cell analysis using connective tissue fibroblasts showed that high-frequency contactless impedance spectroscopy and time-resolved quantification of IL-6 secretion using ELISA provided similar results following stimulation with circulating pro-inflammatory cytokines IL-1β and TNFα. The combination of microfluidics with contactless impedance sensing and time-resolved quantification of stress factor release will provide biologist with a new tool to (a) establish a variety of uniform cell culture surfaces that feature complex biochemistries, micro- and nanopatterns; and (b) to simultaneously characterize cell responses under physiologically relevant conditions using a complementary non-invasive cell analysis method.

AB - We have developed a lab-on-a-chip system for continuous and non-invasive monitoring of microfluidic cell cultures using integrated high-frequency contactless impedance spectroscopy. Electrically insulated microfabricated interdigitated electrode structures were embedded into four individually addressable microchambers to reliably and reproducibly detect cell-substrate interactions, cell viability and metabolic activity. While silicon nitride passivated sensor substrates provided a homogeneous cell culture surface that minimized cell orientation along interdigitated electrode structures, the application of high-frequency AC fields reduced the impact of the 300 nm thick passivation layer on sensor sensitivity. The additional implementation of multivariate data analysis methods such as partial least square (PLS) for high-frequency impedance spectra provided unambiguous information on intracellular pathway activation, up and down-regulation of protein synthesis as well as global cellular stress responses. A comparative cell analysis using connective tissue fibroblasts showed that high-frequency contactless impedance spectroscopy and time-resolved quantification of IL-6 secretion using ELISA provided similar results following stimulation with circulating pro-inflammatory cytokines IL-1β and TNFα. The combination of microfluidics with contactless impedance sensing and time-resolved quantification of stress factor release will provide biologist with a new tool to (a) establish a variety of uniform cell culture surfaces that feature complex biochemistries, micro- and nanopatterns; and (b) to simultaneously characterize cell responses under physiologically relevant conditions using a complementary non-invasive cell analysis method.

KW - Cell Cycle Checkpoints

KW - Cell Line

KW - Cell Survival

KW - Cytokines

KW - Dielectric Spectroscopy

KW - Enzyme-Linked Immunosorbent Assay

KW - Fibroblasts

KW - Humans

KW - Interleukin-6

KW - Lab-On-A-Chip Devices

KW - Least-Squares Analysis

KW - Microfluidic Analytical Techniques

KW - Principal Component Analysis

KW - Stress, Physiological

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1039/c4an00824c

DO - 10.1039/c4an00824c

M3 - Journal article

C2 - 25137192

VL - 139

SP - 5271

EP - 5282

JO - The Analyst

JF - The Analyst

SN - 0003-2654

IS - 20

ER -