Spine-shaped gold protrusions improve the adherence and electrical coupling of neurons with the surface of micro-electronic devices

Abstract

Interfacing neurons with micro-and nano-electronic devices has been a subject of intense study over the last decade. One of the major problems in assembling efficient neuroelectronic hybrid systems is the weak electrical coupling between the components. This is mainly attributed to the fundamental property of living cells to form and maintain an extracellular cleft between the plasma membrane and any substrate to which they adhere. This cleft shunts the current generated by propagating action potentials and thus reduces the signal-to-noise ratio. Reducing the cleft thickness, and thereby increasing the seal resistance formed between the neurons and the sensing surface, is thus a challenge and could improve the electrical coupling coefficient. Using electron microscopic analysis and field potential recordings, we examined here the use of gold micro-structures that mimic dendritic spines in their shape and dimensions to improve the adhesion and electrical coupling between neurons and micro-electronic devices. We found that neurons cultured on a gold-spine matrix, functionalized by a cysteine-terminated peptide with a number of RGD repeats, readily engulf the spines, forming tight apposition. The recorded field potentials of cultured Aplysia neurons are significantly larger using gold-spine electrodes in comparison with flat electrodes.

Frequency-dependent signal transfer at the interface between electrogenic cells and nanocavity electrodes

“…The seal resistance for the simulated signals above are in the range of a few tens of M s. Previously reported seal resistances for plain chips are a factor of 10 smaller [33,48]. So far, high seal resistances without active suction or penetration of the probe have only been shown for spine-shaped gold protrusions [49]. We explain the excellent sealing of the electrode by the small opening which can be covered completely by the cell.…”

Long-Term, Multisite, Parallel, In-Cell Recording and Stimulation by an Array of Extracellular Microelectrodes

“…This peptide was referred to as the engulfment promoting peptide (EPP): CKKKKKKKKKKPRGDMPRGDMPRGDMPRGDM. Using electron microscopy (Hai et al 2009a;Spira et al 2007), we established that the neuron-gME formed a reduced cleft width and increased contact area. Nevertheless the gME clearly maintains an extracellular position in respect to the neuron's plasma membrane.…”

“…In recent years, we began to develop a new approach to better interface neurons and lithographed sensing pads (Hai et al 2009a(Hai et al ,b, 2010Spira et al 2007). To that end, we selected what we believed to be a suitable three-dimensional (3D) geometry and dimensions for the microelectrodes (E) that protrude from the glass substrate and used a specific peptide to functionalize the microelectrodes such that it will activate conserved cell biological mechanisms to generate intimate contact between the neurons and the E. The 3D E that we designed to facilitate the formation of an intimate contact is a gold mushroom-shaped microelectrode [gME, also termed FGSE-functionalized gold-spine electrode-in a previous brief communication (Hai et al 2010)], which protrudes from the substrate to a height of 1-1.5 m (Fig.…”

Prospects for Neuroprosthetics: Flexible Microelectrode Arrays with Polymer Conductors

“…Spine-shaped gold protrusions, electroplated on patterned Cu on glass, insulated by a SiC/Si 3 N 4 /SiO 2 stack (Hai et al, 2009;Hai et al, 2010) …”