Transfer of vertical nanowire arrays on polycaprolactone substrates for biological applications

We used two methods, namely stamping and printing, to transfer arrays of epitaxial gallium phosphide (Gap) nanowires from their growth substrate to a soft, biodegradable layer of polycaprolactone (PCL). Using the stamping method resulted in a very inhomogeneous surface topography with a wide distribution of transferred nanowire lengths, whereas using the printing method resulted in an homogeneous substrate topography over several mm(2). PC12 cells were cultured on the hybrid nanowire-PCL substrates realized using the printing method and exhibited an increased attachment on these substrates, compared to the original nanowire-semiconductor substrate. Transferring nanowires on PCL substrates is promising for implanting nanowires in-vivo with a possible reduced inflammation compared to when hard semi-conductor substrates are implanted together with the nanowires. The nanowire-PCL hybrid substrates could also be used as biocompatible cell culture substrates. Finally, using nanowires on PCL substrates would enable to recycle the expensive GaP substrate and repeatedly grow nanowires on the same substrate. (C) 2015 The Authors. Published by Elsevier B.V