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. 2024 Mar 25:12:1376151.
doi: 10.3389/fbioe.2024.1376151. eCollection 2024.

Utilizing GO/PEDOT:PSS/PtNPs-enhanced high-stability microelectrode arrays for investigating epilepsy-induced striatal electrophysiology alterations

Meiqi Han  1   2 , Yu Wang  1   2 , Luyi Jing  1   2 , Gucheng Yang  1   2 , Yaoyao Liu  1   2 , Fan Mo  1   2 , Zhaojie Xu  1   2 , Jinping Luo  1   2 , Qianli Jia  1   2 , Yuxin Zhu  1   2 , Hanwen Cao  1   2 , Xinxia Cai  1   2 , Juntao Liu  1   2
Affiliations

Utilizing GO/PEDOT:PSS/PtNPs-enhanced high-stability microelectrode arrays for investigating epilepsy-induced striatal electrophysiology alterations

Meiqi Han et al. Front Bioeng Biotechnol. .

Abstract

The striatum plays a crucial role in studying epilepsy, as it is involved in seizure generation and modulation of brain activity. To explore the complex interplay between the striatum and epilepsy, we engineered advanced microelectrode arrays (MEAs) specifically designed for precise monitoring of striatal electrophysiological activities in rats. These observations were made during and following seizure induction, particularly three and 7 days post-initial modeling. The modification of graphene oxide (GO)/poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/platinu-m nanoparticles (PtNPs) demonstrated a marked reduction in impedance (10.5 ± 1.1 kΩ), and maintained exceptional stability, with impedance levels remaining consistently low (23 kΩ) even 14 days post-implantation. As seizure intensity escalated, we observed a corresponding increase in neuronal firing rates and local field potential power, with a notable shift towards higher frequency peaks and augmented inter-channel correlation. Significantly, during the grand mal seizures, theta and alpha bands became the dominant frequencies in the local field potential. Compared to the normal group, the spike firing rates on day 3 and 7 post-modeling were significantly higher, accompanied by a decreased firing interval. Power in both delta and theta bands exhibited an increasing trend, correlating with the duration of epilepsy. These findings offer valuable insights into the dynamic processes of striatal neural activity during the initial and latent phases of temporal lobe epilepsy and contribute to our understanding of the neural mechanisms underpinning epilepsy.

Keywords: PEDOT:PSS; graphene oxide; microelectrode arrays; striatum; temporal lobe epilepsy.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
The design and fabrication of MEAs. (A) Decomposition diagram of the electrode structure, consisting of a Si base layer, a SiO2 insulating layer, a Ti/Pt metal layer, and a SiO2/Si3N4 insulating layer. (B) MEAs (C) Flow chart of electrode fabrication: (a) SOI sheet. (b) Thermal oxidation of silicon in the top layer of SOI generates silica. (c) Lithography (AZ5214) generates a pattern of metal sputtering and sputters Ti/Pt. (d) The sputtered metal layer is patterned using the lift-off process. (e) Inductively coupled plasma chemical vapour deposition deposited SiO2/Si3N4. (f) Lithography (AZ1500) generates site and pad photoresist patterns and performs insulating layer (SiO2/Si3N4) etching. (g) Lithography (AZ4620) generates a photoresist pattern of the MEA shape. (h) The SiO2/Si layer underwent an etching process. (i) MEAs were released by KOH wet etching after sealing.
FIGURE 2
FIGURE 2
Schematic illustration of the experimental design (A) Scheme of animal experiments, including microelectrode implantation, epilepsy modeling, and signals recording. (B) Schematic representation of the implanted brain area.
FIGURE 3
FIGURE 3
Electrochemical characterization of GO/PEDOT:PSS/PtNPs modified MEAs. (A) Microscopic view of MEAs modified by GO/PEDOT:PSS/PtNPs. (B) Scanning electron microscopy of GO/PEDOT:PSS/PtNPs modified electrode sites. (C) Impedance measurements across the frequency range of 1 Hz–106 Hz. (D) Phase measurements across the frequency range of 1 Hz–106 Hz. (E) Average impedance measurements at 1 kHz (n = 10,*p < 0.05). (F) Average phase measurements at 1 kHz (n = 10,*p < 0.05).
FIGURE 4
FIGURE 4
Characteristics of the electrophysiological signals during pilocarpine-induced seizures. (A) LFP changes during pilocarpine-induced seizures. (B) Spike changes during pilocarpine-induced seizures. (C) Spike firing rate at different degrees of seizure induction (*p < 0.05). (D) Power spectral density in LFPs during different stages of seizure induction. (E) The proportion of LFP power during different stages of seizure induction. (F) Heat map of the correlation matrix across various channels during distinct stages of induced seizure activity.
FIGURE 5
FIGURE 5
Electrophysiological signals at different days in rats. (A) LFP changes in normal Control rats (Control), three days (3 days), and seven days (7 days) after modeling. (B) Spike changes in normal control rats (Control), three days (3 days), and seven days (7 days) after modeling.
FIGURE 6
FIGURE 6
Characteristics of spikes of rats at different days. (A) Average Spike waveform of rats in different stages. (B) Spike firing rate of rats in different days (*p < 0.05). (C) Spike power spectral density of rats in different days. (D) Autocorrelogram of the normal control group. (E) Autocorrelogram of experimental group 3 days after modeling. (F) Autocorrelogram of experimental group 7 days after modeling.
FIGURE 7
FIGURE 7
Characteristics of the LFP of rats at different days. (A) Spectrogram of LFPs at different days. (B) LFP power spectral density at different days. (C) Power of each frequency band and total power of representative channels at different days.
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