Cellular adhesion and neuronal excitability on functionalised diamond surfaces

The resting or evoked activity of neuronal networks can be effectively monitored by using multielectrode arrays (MEA), which allow non-invasive extracellular stimulation and recording of electrical signals in parallel from multiple cells. Diamond possesses unique properties (biocompatibility, optical transparency, possibility of modifying the electronic and hydrophilic/hydrophobic properties at the nanoscale), which makes it a promising material to fabricate stable MEAs for long-term extracellular recordings of electrical and optical signals in living neurons. In order to explore the capability of diamond for fabricating MEAs as cell-based biosensors, we report here the first study on the adhesion and cell excitability (i.e., the ability of cells to generate and propagate trains of electrical impulses) on hydrogen (HTD)- and oxygen (OTD)-terminated diamond surfaces. Adhesion and functional properties of cultured rat hippocampal neurons and chick ciliary ganglia have been quantitatively evaluated using well-established biophysical techniques. Cells survive, adhere and maintain their electrical properties (synaptic activity, ion channels availability, Ca2+ signals during neuronal stimulation) for days provided that mixtures of adhesion molecules (poly-d-lysine, poly-dl-ornithine, laminin) are used to favour cell anchoring on diamond surface.