Manipulation of cross-linking in PEDOT:PSS hydrogels for biointerfacing

Area of Science:

• Materials Science
• Biomedical Engineering
• Polymer Chemistry

Background:

• Conducting hydrogels offer soft interfaces for bioelectronic devices.
• Poly(3,4-ethylene-dioxythiophene):polystyrene sulfonate) (PEDOT:PSS) hydrogels are fabricated using simple solution-based methods.
• Understanding fabrication variables is crucial for optimizing PEDOT:PSS hydrogel properties.

Purpose of the Study:

• To investigate the effect of ionic liquid concentration on PEDOT:PSS hydrogel cross-linking.
• To characterize the resulting hydrogel properties, including stability, swelling, conductivity, stiffness, and cytocompatibility.
• To demonstrate the potential of ionic liquid concentration as a control mechanism for tailoring hydrogel characteristics for biointerfacing.

Main Methods:

• Rheological and gelation kinetic analysis of precursor mixtures.
• Characterization of hydrogel properties: aqueous stability, swelling ratio, electrical conductivity, and mechanical stiffness.
• Assessment of cytocompatibility using human dermal fibroblasts.

Main Results:

• Increasing ionic liquid concentration led to enhanced cross-linking.
• Higher ionic liquid concentrations resulted in decreased swelling and non-network fraction.
• Increased stiffness and conductivity were observed with higher ionic liquid concentrations.
• PEDOT:PSS hydrogels demonstrated stability in cell culture for at least 28 days.
• Hydrogels supported viable and proliferating human dermal fibroblasts for at least two weeks.

Conclusions:

• Ionic liquid concentration is an effective parameter for controlling PEDOT:PSS hydrogel cross-linking and properties.
• Tailored PEDOT:PSS hydrogels exhibit promising stability and cytocompatibility for biointerfacing applications.
• These findings pave the way for developing advanced soft bioelectronic devices through precise material control.