Transfer of vertical nanowire arrays on polycaprolactone substrates for biological applications

Abstract

a b s t r a c tWe 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.

High density nanowire electrodes for intracortical microstimulation

“…Nano sized electrodes offer advantages such as minimum cell-to-electrode distance and better resolution [15]. Nanoelectrodes have been grown epitaxially for cortex stimulation and recording [16,17].…”

Light-Emitting GaAs Nanowires on a Flexible Substrate

“…There have been a small number of reports of techniques that maintain the vertical orientation of the nanowires. These include an etching step that forms horizontal cracks in the nanowires, allowing them to be broken away from the substrate, , a printing method, insertion into a PMMA [poly­(methyl methacrylate)] layer, or embedding in a polydimethylsiloxane (PDMS) polymer matrix . However, all of these techniques were demonstrated for semiconductor nanowires with indirect band gaps, Si in references , , , and , and GaP in ref ; hence, no studies of the emissive properties of the transferred nanowires were possible.…”

“…These include an etching step that forms horizontal cracks in the nanowires, allowing them to be broken away from the substrate, , a printing method, insertion into a PMMA [poly­(methyl methacrylate)] layer, or embedding in a polydimethylsiloxane (PDMS) polymer matrix . However, all of these techniques were demonstrated for semiconductor nanowires with indirect band gaps, Si in references , , , and , and GaP in ref ; hence, no studies of the emissive properties of the transferred nanowires were possible. The transfer of nanowires retaining a high emission quantum efficiency is challenging because any surface damage has potentially a high impact in these large surface area to volume structures.…”

“…For example, the etching steps of refs and may prove problematic, with the former also including a high temperature, high pressure step. Other techniques appear to require relatively long nanowires (refs , , and ) and result in nanowires with a significant length distribution (refs and ), or both, which complicates subsequent electrical contact. It is therefore necessary to develop a technique that allows the transfer of large area arrays of vertical light-emitting nanowires while preserving their initial high quantum efficiency.…”

Nanowire Electrodes Integrated on Tip of Microwire for Peripheral Nerve Stimulation

“…Nanoelectrodes have been grown epitaxially for cortical stimulation [16], with stamping and printing method [17], gallium phosphide NWs for acute in vivo recording in rat cortex [18]. Further, Nanowires were grown using electron-beam-induced deposition for recording neural signals in the rat brain [19] and silicon-based intracellular electrodes have been developed for neural recording [20].…”