SU-8-based nanoporous substrate for migration of neuronal cells

Most polymer-based biomedical implantable microscale devices have a smooth surface, so that cell seeding is suppressed in the absence of an adhesive material coating on the surface. SU-8 is a negative photoresist, and is widely used for the fabrication of micro-/nanoscale biomedical devices. A physical surface modification technique was introduced in this study to enhance cell viability and mobility on a SU-8 substrate. To characterize cell viability and mobility, four types of SU-8 substrate were prepared: flat bare substrate, poly-l-lysine (PLL)-coated flat bare substrate, nanoporous substrate, and PLL-coated nanoporous substrate. Rat pheochromocytoma (PC12) cells were cultured on these substrates, and nerve growth factor (NGF) was added to induce differentiation of the PC12 cells. On the seventh day of cell culture, PC12 cells on the nanoporous SU-8 substrate showed 24.3% cell differentiation (neurite outgrowth) versus 1.1% cell differentiation on the flat bare substrate. It was also found that cells had a tendency to move from a flat surface to a nanoporous region. These cellular activities on the nanoporous SU-8 substrate suggest that nanopores can be used to regulate cellular activities and can be applied to SU-8-based microscale biomedical devices.