Process entanglement as a neuronal anchorage mechanism to rough surfaces

Abstract

The organization of neurons and glia cells on substrates composed of pristine carbon nanotube islands was investigated using high resolution scanning electron microscopy, immunostaining and confocal microscopy. Neurons were found bound and preferentially anchored to the rough surfaces; moreover, the morphology of the neuronal processes on the small, isolated islands of high density carbon nanotubes was found to be conspicuously curled and entangled. We further demonstrate that the roughness of the surface must match the diameter of the neuronal processes in order to allow them to bind. The results presented here suggest that entanglement, a mechanical effect, may constitute an additional mechanism by which neurons (and possibly other cell types) anchor themselves to rough surfaces. Understanding the nature of the interface between neurons and carbon nanotubes is essential to effectively harness carbon nanotube technology in neurological applications such as neuro-prosthetic and retinal electrodes.

Carbon nanotubes: a promise for nerve tissue engineering?

“…The precise mechanism by which pristine, hydrophobic CNTs provided a prime substrate for neural growth is not known. CNT roughness and the large exposed surface might play an important role in their ability to favor neuronal adhesion [24] . A further possibility is that CNTs could be selectively coated by serum proteins such as fibrinogen and apolipoproteins [25] thus favoring cell adhesion.…”

“…Regarding the mechanism of attachment of cell processes to CNT substrates, Sorkin et al [24] observed that this type of cells tend to intertwine, bend and curl when cultured on a substrate that possesses a roughness comparable with the length scale of its processes (as CNTs are). High resolution scanning electron microscopy (SEM) images revealed that the curly appearance of the processes results from their curling and looping around the CNT surfaces.…”

Implantable Electrodes with Carbon Nanotube Coatings

“…CNT electrodes can be used to position and form stable networks due to the stable and strong physical interactions between the neurons and the CNTs. (Sorkin et al, 2009). The neurons move towards CNT covered surfaces and single neurons move particularly towards the CNT surfaces (Galvan-Garcia et al, 2007).…”

“…Since then studies on neuronal growth and interactions with CNTs have increased tremendously. CNTs tend to create an effective anchoring site for neurons and glial cell differentiation (Jang et al, 2010;Sorkin et al, 2009). CNT coated surfaces are neuro-adhesive in in vitro scenarios (Galvan-Garcia et al, 2007).…”

“…Successful neuronal growth and interaction with CNTs has now been demonstrated by several groups and their neurocompatibility was confirmed (Ben-Jacob & Hanein 2008; Keefer et al, 2008;Khraiche et al 2009;Lovat et al 2005;Lobo et al 2008). CNTs present an effective and consistent anchoring site for neuronal attachment and development, and for glial cell differentiation (Jang et al, 2010;Sorkin et al, 2009). CNT coated surfaces are neuro-adhesive in in vitro applications (Galvan-Garcia et al, 2007;Lobo et al 2008).…”