Synthesis, Characterization, and Evaluation of Disulfide-containing Polyethylenimine Derivative Functionalized Magnetic Carbon Nanotubes as an Efficient Gene vector

The Fourier transform infrared (FT-IR) spectra of CNTs/Fe3O4-SSPEI was recorded on Nicolet Impact-420 Fourier transform infrared spectrometer in the range of 400 - 4000 cm-1. The morphology of CNTs/Fe3O4-SSPEI was conducted by JEM-2100F field emission electron microscopy (TEM, JEOL, Japan). X-ray diffraction (XRD) analysis were performed by a X-ray diffractometer (D/Max-Ⅲc, Japan) using Cu-Kα radiation (λ=1.5406 Å) at room temperature. X-ray photoelectron Spectroscopy (XPS) was taken on an RBD upgraded PHI5000C ESCA system (PerkinElmer) with AI Kα radiation (hv = 1486.6 eV) as the X-ray source for excitation. Thermogravimetric analyzer (TGA) measurement of CNTs/Fe3O4-SSPEI was performed by a TGA STA-409PC thermogravimetric analyzer under N2 in the temperature range 30-800 ˚C with an increasing rate of 5 ˚C min-1. The magnetic properties were measured using a vibrating specimen magnetometer (Squid-VSM) to the field strength of 2 T.