Intracellular and Extracellular Recording of Spontaneous Action Potentials in Mammalian Neurons and Cardiac Cells with 3D Plasmonic Nanoelectrodes

Abstract

Three-dimensional vertical micro- and nanostructures can enhance the signal quality of multielectrode arrays and promise to become the prime methodology for the investigation of large networks of electrogenic cells. So far, access to the intracellular environment has been obtained via spontaneous poration, electroporation, or by surface functionalization of the micro/nanostructures; however, these methods still suffer from some limitations due to their intrinsic characteristics that limit their widespread use. Here, we demonstrate the ability to continuously record both extracellular and intracellular-like action potentials at each electrode site in spontaneously active mammalian neurons and HL-1 cardiac-derived cells via the combination of vertical nanoelectrodes with plasmonic optoporation. We demonstrate long-term and stable recordings with a very good signal-to-noise ratio. Additionally, plasmonic optoporation does not perturb the spontaneous electrical activity; it permits continuous recording even during the poration process and can regulate extracellular and intracellular contributions by means of partial cellular poration.

High‐Aspect‐Ratio Nanostructured Surfaces as Biological Metamaterials

“…However, penetration can be enhanced via electroporation (Figure G), optoporation (Figure H), or by coating nanostraws with strongly cell‐adhering coatings . Bioelectronic experiments show that nanoelectrodes only measure intracellular potentials after poration techniques have been applied, and rapidly return to measuring extracellular potentials in the absence of further external stimulus, again highlighting the need for an external force to disrupt the membrane. Dipalo et al explored this behavior explicitly using a range of nanopillar geometries using fluorescent and electron microscopy, and electrophysiological measurements .…”

“…The use of electroporation to facilitate intracellular electrical access is common throughout the literature and is consistent with the use of electroporation to enhance intracellular delivery, as discussed above. Some have argued that this is problematic when studying neuronal networks, as electroporation overly perturbs the electroanatomy of the cells under investigation and can cause damage to the nuclear membrane . Indeed, Hai and Spira have proposed that electroporation on nanostructures can itself be a technique to study membrane repair dynamics …”

“…Suggested alternatives to electroporation include: using mushroom‐shaped microelectrodes to promote membrane wrapping, by inducing a phagocytosis‐like response; using surface chemistry to facilitate cell membrane penetration; or by using two different physical mechanisms to both stimulate and sense. In the latter case, Dipalo et al have proposed using their plasmonic‐active gold nanopillars to optoporate cells by momentarily irradiating the cell–material interface with infrared light ( Figure ) . This approach allows them to continuously monitor the electrical environment via the gold nanopillar, with no interruption from electroporation.…”

“…B) The equivalent circuit diagram model of the cell–nanostructure interface, illustrating how sequentially optoporating nanoelectrodes reduce the junction resistance between cell and electrode, while increasing the membrane seal resistance. A,B) Adapted with permission . Copyright 2017, American Chemical Society.…”

Nongenetic Optical Methods for Measuring and Modulating Neuronal Response

“…In contrast to this, M. Dipalo et al 53 has recently shown that optical methods can be used to aid device integration. Highlighting a previously described method for generating transient holes in the cell membrane via a plasmonicly created pressure waves 54 , they were able to optically introduce nanocylinder electrodes intracellularly in a non-invasive manner.…”