2 research outputs found
Electric Cell-Substrate Impedance Sensing of Cellular Effects under Hypoxic Conditions and Carbonic Anhydrase Inhibition
Tumor hypoxia provides a dynamic environment for the cancer cells to thrive and metastasize. Evaluation of cell growth, cell-cell, and cell surface interactions in hypoxic conditions is therefore highly needed in the establishment of treatment options. Electric cell-substrate impedance sensing (ECIS) has been traditionally used in the evaluation of cellular platforms as a real-time, label-free impedance-based method to study the activities of cells grown in tissue cultures, but its application for hypoxic environments is seldom reported. We present real-time evaluation of hypoxia-induced bioeffects with a focus on hypoxic pH regulation of tumor environment. To this end, multiparametric real-time bioanalytical platform using electrical impedance spectroscopy (EIS) and human colon cancer HT-29 cells is advanced. A time series of EIS data enables monitoring with high temporal resolution the alterations occurring within the cell layer, especially at the cell-substrate level. We reveal the dynamic changes of cellular processes during hypoxic conditions and in response to application of acetazolamide (AZA), a carbonic anhydrase inhibitor. Optical evaluation and pH assessment complemented the electrical analysis towards establishing a pattern of cellular changes. The proposed bioanalytical platform indicates wide applicability towards evaluation of bioeffects of hypoxia at cellular level
Complementarity of EIS and SPR to Reveal Specific and Nonspecific Binding When Interrogating a Model Bioaffinity Sensor; Perspective Offered by Plasmonic Based EIS
The present work compares the responses
of a model bioaffinity sensor based on a dielectric functionalization
layer, in terms of specific and nonspecific binding, when interrogated
simultaneously by Surface Plasmon Resonance (SPR), non-Faradaic Electrochemical
Impedance Spectroscopy (EIS), and Plasmonic based-EIS (P-EIS). While
biorecognition events triggered a sensitive SPR signal, the related
EIS response was rather negligible. Contrarily, even a limited nonspecific
adsorption onto the surface of the metallic electrode, allowed by
the intrinsic imperfect compactness of the functionalization layers,
was signaled by EIS and not by SPR. The source of this finding has
been addressed from both theoretical and experimental perspectives,
demonstrating that EIS signals are mainly sensitive to adsorptions
that alter the current pathway through defects of the functionalization
layer exposing the electrode. These observations are of importance
for those developing biosensors analyzed by SPR, EIS, or the novel
combination of the two methods (P-EIS). A possible application of
the observed complementarity of the two methods, namely assessment
of sample purity in respect to a target analyte is highlighted. Moreover,
the possibility of false-positive EIS responses (determined by nonspecific
binding) when assessing samples containing complex matrices or consisting
of small molecular weight analytes is emphasized