Well-Ordered Porous Conductive Polypyrrole as a New Platform for Neural Interfaces

Abstract

We present the preparation of electrically conductive, porous polypyrrole surfaces and demonstrate their use as an interactive substrate for neuronal growth. Nerve growth factor (NGF)-loaded porous conducting polymers were initially prepared by electrochemical deposition of a mixture of pyrrole monomers and NGF into two- or three-dimensional particle arrays followed by subsequent removal of a sacrificial template. Morphological observation by scanning electron microscopy (SEM) revealed these to possess high regularity and porosity with well-defined topographical features. A four-point probe study demonstrated remarkable electrical activities despite the presence of voids. In addition, we investigated the effects of these surfaces on cellular behaviors using PC 12 cells in the presence and absence of electrical stimulation. Our results suggest that the surface topography as well as an applied electrical field can play a crucial role in determining further cell responses. Indeed, surface-induced preferential regulation leads to enhanced cellular viability and neurite extension. Establishing the underlying cellular mechanisms in response to various external stimuli is essential in that one can elicit positive neuronal guidance and modulate their activities by engineering a series of electrical, chemical, and topographical cues.

SU-8-based nanoporous substrate for migration of neuronal cells

“…Nanopatterned surfaces are known to affect cell behavior, such as attachment [8,9], migration [10], and differentiation [11][12][13][14]. Thus, nanopatterns can be used on the surface of an implantable medical device to control cellular activities for different biomedical applications.…”

CHAPTER 8. Bioactive Conducting Polymers for Optimising the Neural Interface

“…Kang et al created nanoporous PPy/PSS coatings loaded with nerve growth factor (NGF) by electrodepositing onto electrodes coated with polystyrene beads. 41 Electrodes were soaked in tetrahydrofuran after deposition in order to remove the polystyrene template. The nanoporous PPy/PSS coatings had improved electrical properties due to increased surface area.…”

Biomedical applications of electrically conductive polymeric systems

“…Moreover, electroactive polymers, other than PPy, could also be used for the electrochemically controlled release of various agents. Kang, Borgens and Cho [84] deposited PPy electrochemically on colloidal polystyrene arrays, which served as a template for the formation of a well ordered porous PPy doped with NGF and sodium salt of poly(styrene sulfonate) (NaPSS). They deposited, under constant catholic potential of 0.9V aqueous mixture of 0.1M pyrrole, 0.1M NaPSS and 100µg/ml of NGF.…”

“…Cho and Borgens [85] prepared biotin doped porous PPY, using a procedure, which was in principle analogous to the procedure described in ref. 84. 9mM of Biotin and 0.01M NaDBS were used instead NGF and NaPSS, and the applied potential was 0.7V not 0.9V.…”