Growing neural networks on gold surface plasmon resonance imaging sensors

Summary form only given. Surface plasmon resonance (SPR) is sensitive to changes of refractive index at a metal-dielectric interface. This technique has been applied to image networks of neurons non-invasively. The long term survival of active neural networks on SPR sensors requires optimisation of both the cell culture and the surface chemistry to ensure neurons adhere and grow uniformly. Here we present chemical modifications to gold SPR sensors and assess their suitability for culturing embryonic rat hippocampal neurons. Through the use of gold-thiol chemistry we prepared peptide terminated surfaces. The peptide is a fragment from the extracellular matrix protein laminin and contains the amino acid sequence IKVAV, known to promote neural adhesion. Our results show that neurons formed into clusters following initial cell adhesion, indicating the surface was inadequate to support healthy cultures. The inclusion of a hetero-bifunctional linker containing PEG (poly(ethylene glycol)) between the gold interface and the peptide produced comparable cultures to control surfaces of poly-L-lysine coated glass. Surface sensitive techniques including secondary ion mass spectrometry, X-ray photoelectron spectroscopy and the quartz crystal microbalance were then used to characterise the chemistry of these surfaces. Results from the quartz crystal microbalance indicated that, for peptide modified surfaces, adsorption of protein components from the culture media was lower with inclusion of the PEG linker. The result suggests that PEG acts to prevent non-specific protein adsorption, allowing the neuron to adhere to the surface peptide and remain viable.