Long-term adhesion and survival of dissociated cortical neurons on miniaturised chemical patterns

The influence of neuron-adhesive pattern geometry on long-term adhesion, survival and pattern compliance of cortical neuronal tissue was studied over a period of 15 days. The results are relevant for a successful, long-term integration of neuronal cells with electrodes from micro-electronic devices. Microwells (depth 0.5 microm), with diameters of 25, 50, 100 and 150 microm and spacing distances of 15, 30, 60 and 90 microm, were etched in a neuron-repellent fluorocarbon (FC) layer and coated with neuron-adhesive polyethylenimine (PEI). Results showed that adhesion, survival and compliance to the underlying patterns were geometry- and time-dependent. After 1 day, adhesion was inversely proportional to the diameter of the microwells, thus favouring the 25 microm microwells. However, adhesion was best on 50 microm microwells after 15 days. Survival of neurons was limited on 25 microm microwells (viability function V(D, T) was 0.08), as opposed to the better survival on 150 microm microwells (V(D, T) was 0.25) after 15 days. In summary, the study shows that the chemical patterns with microwells of 150 microm diameter (90 microm spacing gap) are most suitable for application on neuro-electronic devices owing to the better long-term survival and high pattern compliance of the neuronal cells.