Preparation And Characterization Of Electrospun Biodegradable Polymer And Multi-Walled Carbon Nanotubes Composite Nanofibers

In this paper, the conductive poly(d,l-lactide)/multi-walled carbon nanotubes (PLA/MWCNTs) composite fibrous scaffolds with two morphologies (random oriented and aligned fiber) and polycaprolactone/multi-walled carbon nanotubes (PCL/MWCNTs) composite fibrous scaffold containing green tea polyphenols (GTP) were successfully fabricated by electrospinning. The biodegradable materials we selected PLA and PCL are non-toxic and have excellent biocompatibility; MWCNTs has excellent mechanical properties, electrical conductivity and good biocompatibility. Therefore, it is foreseeable that the fibrous scaffolds we prepared have broad application in tissue engineering and drug controlled release.Firstly, the characterization of scanning electron microscopy (SEM), transmission electron microscopy (TEM), universal mechanical testing machine, surface resistivity testing, materials degradation in vitro were given to conductive PLA/MWCNTs composite fibrous scaffold. Results showed that:the conductive PLA/MWCNTs composite fiber had uniform diameter and good morphology; MWCNTs dispersed well within the composite fiber; mechanical properties of composite PLA/MWCNTs fibers increased significantly compared with pure PLA fibers, and the mechanical properties of aligned composite fibrous scaffold were better than random oriented fibrous scaffold when content of MWCNTs was the same; electrical percolation threshold was existed when content of MWCNTs was 3%; in vitro degradation of PLA/MWCNTs composite fibrous scaffold was affected significantly by MWCNTs.Secondly, in order to study the coordinate effect of micro-current stimulation and morphology of scaffold on the growth of obsteoblast, three different sizes of direct current stimulation (50,100,200μA) was applied to the obsteoblast through conductive PLA/MWCNTs fibrous scaffold by a home-made device. The characterization of alamar blue, optical microscope, fluorescence microscope and scanning electron microscopy were executed. Results showed that: without electrical stimulation, obsteoblast on random oriented fibrous scaffold grew surroundly, while obsteoblast on aligned fibrous scaffold grew along the orientation of aligned fibers and the cell proliferation was better especially when content of MWCNTs was 3%; additionally, electrical stimulation of 50 and 100μA can promote the growth of osteoblasts, especially for 100μA, while electrical stimulation of 200μA led to massive death for osteoblasts; at last, the electrical stimulation caused obsteoblast grown along the direction of the direct current (the effect of 100μA was best of all) no matter for random oriented or aligned fibrous scaffold.Finally, the characterization of fourier transform infrared analyzer (FTIR), scanning electron microscopy (SEM), laser scanning confocal microscope, universal mechanical testing machine, materials degradationin vitro, drug controlled release in vitro and cell experiment (OB, A549, Hep G2) were applied to PCL/MWCNTs composite electrospun fibrous scaffold containing GTP. Results showed that:GTP successful adhere to the surface of MWCNTs by noncovalent interactions; PCL/MWCNTs composite electrospun fibrous scaffold had wide distribution of diameter and good morphology, MWCNTs dispersed well within the fiber; PCL/MWCNTs composite fibrous scaffold possessed enhanced mechanical properties due to MWCNTs although it was weaken by GTP; in vitro degradation of PCL/MWCNTs composite fibrous scaffold was affected by MWCNTs and the content of GTP; the PCL/MWCNTs composite fibrous scaffold containing GTP could effectively control the burst release of GTP compared to pure PCL scaffold with GTP, and they had minor cytotoxic to normal obsteoblast and inhibition to tumor cells (A549 and Hep G2).