Earlier reports that cultured human stem cell-derived neuronal cells on patterned surfaces were directed towards short-term applications - one study reported culture of neural progenitor cells on patterned surfaces for only 2 days [39] and a second study investigated the adherence and differentiation capacity of human cord blood-derived neural stem cells for 7 days [40]. Other examples cultured primary neurons on micropatterned substrates for several days to a few weeks [13, 15, 17]. It is not clear why the patterned monolayers are effective at maintaining the patterned neurons for periods of months in culture. Previous examples of patterned cell cultures on monolayers of alkanethiolates on gold have found that the cells typically remain in their initial positions for one to four weeks [19-21]. In those cases, it is likely that the protein resistant oligo(ethylene glycol) groups were oxidatively damaged, compromising the protein-resistant property. We did not alter those patterned substrates to achieve the long-term culture of neurons reported in this work; rather, the stability must reflect either a less oxidative (or otherwise reactive) environment near the cells or a lack
