Microporous, non-woven nanofiber scaffolds of poly(vinylidene fluoride) (PVDF)-multiwalled carbon nanotubes (MWCNTs) were made by electrostatic fiber spinning. In this process, polymer fibers with diameters down to the nanometer range, or nanofibers, are formed by subjecting a fluid jet to a high electric field. Cell adhesion and proliferation were measured with MTT (Methylthiazolyldiphenyl -tetrazolium bromide) assay. RT4-D6P2T (Schwannoma cell line of rats), U87-MG (glioblastoma cell line of human) and SH-SY5Y (neuroblastoma cell line of human) cells were cultured in Dulbecco's Modified Eagle's medium (DMEM) supplemented with 10% (v/v) fetal bovine serum (FBS) and 1% (v/v) antibiotic/antimycotic solution at 37? in humidified and 5% CO2 atmosphere. Scanning electron microscopy (SEM), histological and immunohistochemical examinations were performed. Penetration of cells and abundant extracellular matrix were observed in the cell-polymer constructs for 7days. SEM showed that the surfaces of the cell-polymer constructs were covered with cell multilayers after 1 day. The cell-polymer constructs were cultured with osteogenic supplements under dynamic culture conditions for up to 7 days. Three types of nervous system cells looks like that there is appropriate concentration of MWCNT for each cell. RT4-D6P2T cells were showed the best adhesion on PVDF sheet with 0.5% MWCNT and that significantly higher than 20% compared with pure PVDF. But the adhesion rate were decreased on PVDF sheet with 1% MWCNT than that. U87-MG cells were steadily increased from PVDF with 0.1% MWCNT with increasing concentration than pure PVDF. And SH-SY5Y cells were showed only high attachment on PVDF sheet with 1% MWCNT than pure PVDF.
We also investigated the effects of varying the MWCNT content, as well as the additional use of drawing and poling on the polymorphic behavior and electroactive (piezoelectric) properties of the membranes obtained. Fourier transform infrared spectroscopy and wide angle X-ray diffraction revealed that dramatic changes occurred in the beta-phase crystal formation with the MWCNT loading. This was attributed to the nucleation effects of the MWCNTs as well as the intense stretching of the PVDF jets in the electrospinning process. The remanent polarization and piezoelectric response increased with the amount of MWCNTs and piezoelectric b-phase crystals. In the poled samples, the incorporation of the MWCNTs made it easy to obtain efficient charge accumulation in the PVDF matrix, resulting in the conversion of alpha-phase into beta-phase as well as the enhancement of remanent polarization and the mechanical displacement. The cell growth showed strong correlation with the membranes piezoelectric property changes. Further evidences of the piezoelectric effect on the cell gowth are presented.