# Electrically active hydrogels based on PEDOT:PSS for neural cultures

## TL;DR

This paper introduces a new type of electrically active hydrogel suitable for interfacing with neural cells in lab settings.

## Contribution

The study presents a novel hydrogel combining alginate, laminin, and PEDOT:PSS for stable, long-term neural cell interfacing.

## Key findings

- The hydrogels showed viscoelastic properties suitable for neural tissue interfacing with moduli in the 1–10 kPa range.
- PEDOT:PSS significantly improved conductivity and charge storage in the hydrogels.
- The hydrogels maintained electrochemical stability over 80 cycles and supported neuron cultures for 28 days.

## Abstract

Electrically active hydrogels are attracting significant interest as biohybrid materials for electrical interfacing with biological tissues. Here, we report the development of electrically active hydrogels, specifically engineered for in vitro neural cell cultures. The hydrogels’ matrix comprises a viscoelastic alginate primary network, interpenetrated by a secondary network formed by the neural cell-adhesive protein, laminin. Conducting poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) particles are embedded throughout the hydrogel matrix, serving as the electrically active filler phase. Oscillatory rheology confirmed the viscoelastic nature of the composite hydrogels, with storage and loss moduli in the range of 1–10 kPa, suitable for neural tissue interfacing. The hydrogels exhibited high optical transparency across the visible spectrum. At a wavelength of 500 nm, transmission exceeded 45% for 400 µm thick hydrogels and was further enhanced to over 60% by reducing the hydrogel thickness to 150 µm. We established a reproducible protocol for electrochemical impedance spectroscopy and cyclic voltammetry measurements, demonstrating that the incorporation of PEDOT:PSS significantly enhanced both conductivity and charge storage capacitance of hydrogel films. The alginate–laminin–PEDOT:PSS hydrogels demonstrated excellent operational stability, maintaining consistent electrochemical performance over 80 charging/discharging cycles and remaining structurally and functionally stable under cell culture conditions for over four weeks. Cortical neuron cultures derived from human induced pluripotent stem cells prove the stability and cytocompatibility of our proposed hydrogels for over 28 days in culture. Collectively, these results highlight the potential of electrically active hydrogels loaded with PEDOT:PSS as soft, bioelectronic interfaces for neural engineering applications.

Electrically active hydrogels are attracting significant interest as biohybrid materials for electrical interfacing with biological tissues.