Simultaneous Presentation of Dexamethasone and Nerve Growth Factor via Layered Carbon Nanotubes and Polypyrrole to Interface Neural Cells

The implantation of neural electrodes usually inducesacute andchronic inflammation, which can result in the formation of glial scarsencapsulating the implanted electrodes and the loss of neurons nearthe active electrode sites. Local presentation of anti-inflammatorydrugs or neural protective factors has been evidenced as an effectivestrategy to modulate inflammatory responses and promote electrode-neuronintegration. Here, a novel delivery system for the simultaneous presentationof both anti-inflammatory drugs (dexamethasone, Dex) and nerve-growth-promotingfactors (nerve growth factor, NGF) from the electrode sites was developedvia layer-structured carbon nanotubes and conductive polymers. Themodified electrodes exhibited higher charge storage capacitance andlower electrochemical impedance compared to unmodified electrodesand electrodes coated with polypyrrole/Dex. Dex released from thefunctional coating under controlled electrochemical stimulation wasable to inhibit the lipopolysaccharide-induced secretion or mRNA transcriptionof inflammatory cytokines, including nitric oxide, TNF-& alpha;, andIL-6 in RAW264.7 cells, and control the activation of cultured astrocytes.In addition, the functional coatings did not show a toxic effect onPC12 cells and primary neural cells but exhibited promoted activitieson the adhesion, growth, and neurite extension of neural cells.

Automated summary

A novel delivery system for simultaneous release of anti-inflammatory drugs and nerve growth factors was developed, which effectively suppressed inflammation and promoted electrode-neuron integration. The functional coatings demonstrated excellent biocompatibility, enhancing neural cell adhesion, growth, and neurite extension.