Radio frequency plasma assisted surface modification of Fe3O4 nanoparticles using polyaniline/polypyrrole for bioimaging and magnetic hyperthermia applications

Abstract

Surface modification of superparamagnetic Fe₃O₄ nanoparticles using polymers (polyaniline/polypyrrole) was done by radio frequency (r.f.) plasma polymerization technique and characterized by XRD, TEM, TG/DTA and VSM. Surface-passivated Fe₃O₄ nanoparticles with polymers were having spherical/rod-shaped structures with superparamagnetic properties. Broad visible photoluminescence emission bands were observed at 445 and 580 nm for polyaniline-coated Fe₃O₄ and at 488 nm for polypyrrole-coated Fe₃O₄. These samples exhibit good fluorescence emissions with L929 cellular assay and were non-toxic. Magnetic hyperthermia response of Fe₃O₄ and polymer (polyaniline/polypyrrole)-coated Fe₃O₄ was evaluated and all the samples exhibit hyperthermia activity in the range of 42-45 °C. Specific loss power (SLP) values of polyaniline and polypyrrole-coated Fe₃O₄ nanoparticles (5 and 10 mg/ml) exhibit a controlled heat generation with an increase in the magnetic field.

Fig. 1

XRD pattern of a Fe₃O₄, b PANI-coated Fe₃O₄, and c polypyrrole-coated Fe₃O₄ nanoparticles

Fig. 2

a TEM image of Fe₃O₄, b Histogram of particle sizes obtained from TEM, c HRTEM image and d SAED pattern of Fe₃O₄

Fig. 3

a TEM image of iron oxide nanoparticles with spherical and rod-shaped morphology (Fe₃O₄). The inset shows the average diameter of nanorods and b HRTEM image of nanorod iron oxide

Fig. 4

a TEM image of PANI-coated Fe₃O₄, b histogram of particle sizes obtained from TEM, c HRTEM image and d SAED pattern of PANI-coated Fe₃O₄

Fig. 5

a TEM image of polypyrrole-coated Fe₃O₄, b histogram of particle sizes obtained from TEM, c HRTEM image and d SAED pattern of polypyrrole-coated Fe₃O₄

Fig. 6

Photoluminescence spectra of Fe₃O₄, PANI-coated Fe₃O₄ and polypyrrole-coated Fe₃O₄ under an excitation wavelength of 325 nm

Fig. 7

Bright field and fluorescence images of L929 cell lines treated with a Fe₃O₄, b polyaniline-coated Fe₃O₄ nanoparticles, and c polypyrrole-coated Fe₃O₄ nanoparticles (×40 magnification)

Fig. 8

Cytotoxicity studies of MTT assays for different concentrations of Fe₃O₄, PANI and polypyrrole-coated Fe₃O₄ nanoparticles incubated in U87 cell lines

Fig. 9

Magnetic hysteresis curves of a Fe₃O₄, b PANI-coated Fe₃O₄, and c polypyrrole-coated Fe₃O₄ at 300 K

Fig. 10

Time-temperature graph of a Fe₃O₄, b PANI-coated Fe₃O₄, and c polypyrrole-coated Fe₃O₄ with 1 mg concentration on exposure to 200–400 A (ac) current with a frequency of 280 kHz

Fig. 11

Time–temperature graph of a Fe₃O₄, b PANI-coated Fe₃O₄, and c polypyrrole-coated Fe₃O₄ of 3 mg concentration on exposure to 200–400 A (ac) current with a frequency of 280 kHz