Conductive Conjugated Polymer Nanocapacitors for Localized Electrical Neurostimulation

Abstract

Noninvasive manipulation of cell signaling is critical in basic neuroscience research and in developing therapies for neurological disorders and tissue engineering and regenerative medicine approaches. In this work, biomimetic synthesized conductive copolymer 3,4-ethylenedioxythiophene (EDOT)-Pyrrole nanoparticles (RB02 NPs) were used for wireless and localized stimulation of neurons. 1 H nuclear magnetic resonance was used to monitor the polymerization. RB02 NPs were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy, and dynamic light scattering. The electrochemical properties were characterized by galvanostatic charge−discharge, voltammetry, and electrochemical impedance spectroscopy. For electrical stimulation of neurons, RB02 NPs were charged by applying 1 V to a NP suspension using platinum electrodes. The effect of NPs on ND7/23 neuron hybrid cell line viability was assessed by live/dead staining using flow cytometry. ND7/23 differentiation was evaluated by cell cytoskeleton staining and quantification of morphological parameters such as the dendrite number and length. Primary cortex neuron stimulation was studied by calcium ion influx detectable through the dynamic fluorescence changes of Fluo-4. RB02 NPs presented no toxicity toward ND7/23 cells. Furthermore, charged NPs enhanced cell differentiation at short times after addition (<6 h). Charged RB02 NPs largely increased the cortex neuronal activity. Altogether, biocompatible copolymer EDOT-Pyrrole nanoparticles present great potential for remote control of neural activities.