Low Cost EIS Methodology to Characterize Microelectrode Arrays used in Biological Applications
Poster Sep 17, 2014
C. A. Santos *, M. A. Flores*, O. Pilloni* , J. Mireles Jr**., A. Falcón ***, T. Fiordelisio ***, L. Oropeza-Ramos*
Electrical Impedance Spectroscopy (EIS) is a valuable and widespread tool to measure properties of an electrode-electrolyte interface present in micro-arrays platforms for recording and stimulating biological tissues. The electric contact between an electrode and a cellular aqueous medium has an impedance whose high values reduce signal to noise ratio and increase signal distortion. This is particularly relevant for microelectrodes due to their reduced dimensions, and having an EIS method available in every laboratory would be highly useful to design and characterize micro electrodes for bio-potential recording and stimulation.
Commercial EIS systems and alternative set-ups that often require an spectrum analyzer are expensive, limiting the electrochemical characterization. In this work, an EIS diagnostic method is presented based on the combination of a straightforward measurement of the time domain input-output voltage ratio, through a conventional oscilloscope, and the indirect analytical determination of the overall impedance in a user defined frequency range.
The method was validated by characterizing an array of silver-chloride micro electrodes soaked in biological medium, used to maintain in vitro cell cultures alive, and results are compared to a commercial EIS system.
The nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are closely related transcription factors that regulate the expression of phase I (cytochrome P450s), phase II metabolizing enzymes and transporter genes in response to xenobiotics, including prescription drugs.READ MORE
We utilized paired synthetic crRNAs coupled with our synthetic tracrRNA in cells transduced with lentiviral Cas9 to perform a functional knockout on hsa-miR-221. This three-part system (crRNA, tracrRNA and Cas9) has demonstrated efficient gene editing when used with only one guide RNA, but the goal was to use two crRNAs to remove the entire stem-loop.READ MORE