Electrically Controlled Neurochemical Release from Dual‐Layer Conducting Polymer Films for Precise Modulation of Neural Network Activity in Rat Barrel Cortex

Abstract

Implantable microelectrode arrays (MEAs) are important tools for investigating functional neural circuits and treating neurological diseases. Precise modulation of neural activity may be achieved by controlled delivery of neurochemicals directly from coatings on MEA electrode sites. In this study, a novel dual-layer conductive polymer/acid functionalized carbon nanotube (fCNT) microelectrode coating is developed to better facilitate the loading and controlled delivery of the neurochemical 6,7-dinitroquinoxaline-2,3-dione (DNQX). The base layer coating is consisted of poly(3,4-ethylenedioxythiophene/fCNT and the top layer is consisted of polypyrrole/fCNT/DNQX. The dual-layer coating is capable of both loading and electrically releasing DNQX and the release dynamic is characterized with fluorescence microscopy and mathematical modeling. In vivo DNQX release is demonstrated in rat somatosensory cortex. Sensory-evoked neural activity is immediately (<1s) and locally (<446 µm) suppressed by electrically triggered DNQX release. Furthermore, a single DNQX-loaded, dual-layer coating is capable of inducing effective neural inhibition for at least 26 times without observable degradation in efficacy. Incorporation of the novel drug releasing coating onto individual MEA electrodes offers many advantages over alternative methods by increasing spatial-temporal precision and improving drug selection flexibility without increasing the device’s size.

Soft Conducting Elastomer for Peripheral Nerve Interface

“…In the design of neural electrodes, CNTs have been used in conjunction with gold deposited on the conductive surfaces and have demonstrated increased charge transfer and decreased impedance at 1 kHz . CNTs have also been functionalized to serve as dopants for conducting polymers and have demonstrated significant improvement not only in chronic single unit recording compared to conventional dopants, but also improved stimulation stability and drug delivery capability . CNTs are mechanically robust and they have been used to create bioinspired hybrid CNT muscles .…”

Biomedical and Tissue Engineering Strategies to Control Foreign Body Reaction to Invasive Neural Electrodes

“…The conducting core of the electrode was based on silicone/poly(3,4-ethylenedioxythiophene)-polyethylene glycol (PEDOT-PEG) elastomer encapsulating 3D CNTs, and it was shown to be more compliant to soft nerve tissue than traditional polyimide implants in terms of FBR. Finally, another CP frequently used as electromechanically active coating for biosensors, implantable gold electrodes ( Yamato et al, 1995 ; Cui et al, 2003 ; Green et al, 2008 ), fiber scaffolds capable of dynamic mechanical actuation ( Gelmi et al, 2016 ) and microelectrode arrays ( Qi et al, 2017 ; Du et al, 2018 ), is the polypyrrole (PPy). However, it has often shown limited performances and chronic recording failure over extended periods of time in vivo , also due to chronic inflammation and fibrotic encapsulation ( Yamato et al, 1995 ; Cui et al, 2003 ; McConnell et al, 2009 ).…”

A Biocompatible Nanofibers‐Based Microchip for Isolation and Nondestructive Release of Fetal Nucleated Red Blood Cells

“…Currently, nanostructure-patterned microchips have drawn great attention in rare cell (e.g., circulating tumor cells [CTCs]) capture which may be conceived as an alternative methodology. [21] For example, bioplatforms decorated with nanoparticles, [22][23][24][25] Si nanowires, [26][27][28] carbon nanotubes, [29] graphene oxide [30,31] or other nanorough surfaces [32,33] have shown great superiority as capture substrates, which has been evaluated by their better efficiency and sensitivity. When compared to flat substrates, nanostructured topographies provide larger surface area for increased antibodies immobilization and also enhance topographical interactions between the substrate and the components of cellular surface.…”