20 Magnetic Memory of Antitumor Magneto-sensitive Nanocomplex
325
20.2.2 Magnetic Studies
The magnetic properties were studied though magnetometry using the “Vibrating
Magnetometer 7404 VSM” (Lake Shore Cryotronics Inc., USA) with magnetic
fields up to 13 kOe. The magnetometer’s sensitivity was 10 −7 emu which allowed
measuring the magnetic moment of samples weighing milligrams. The mass was
determined by the electronic microbalance AB135-S/FACT with auto-identification
(Mettler Toledo, Switzerland) which had a sensitivity of 10 −5 g.
20.2.3 Electron Spin Resonance (ESR) Spectroscopy
ESR spectra were recorded with the spectrometer R¨1307 at liquid nitrogen
temperatures (77 K) in a cylinder resonator with the mode H 011 and frequency
9.15 GHz. The power of microwave radiation was 40 mW, and the magnetic field
modulation frequency was 100 kHz. The samples were placed in a quartz Dewar
flask with an inner diameter of 4.5 mm.
20.3 Experimental Results
20.3.1 Magnetic Studies of Fe 3 O 4 Nanoparticles
The results of magnetic studies of magneto-mechano-chemically activated Fe 3 O 4
NPs are shown on Fig. 20.1 and Table 20.1.
The data analysis testifies that parameters of the samples exposed to various
vibration frequencies had a significant quantitative difference in comparison to the
sample exposed to ER only and the sample without any influence. The studies found
a negative correlation (r = −0.63) between the saturation magnetic moment m s
and vibration frequency f. It is known that the coercivity H c is the intensity of an
applied magnetic field required to reduce the magnetization of the material to 0
after the magnetization of the sample had been driven to saturation. Thus, coercivity
measures the resistance of a ferromagnetic material to demagnetization. The greater
the coercivity, the higher the specific absorption rate (SAR) of electromagnetic
field is detected [10]. In our experiments, all samples had low coercivity H c and a
small area of the hysteresis loop S that can be classified as soft magnetic materials.
The changes of coercivity H c and area of the hysteresis loop S in NPs after
magneto-mechano-chemically activation did not have any correlation with vibration
frequencies.
325
20.2.2 Magnetic Studies
The magnetic properties were studied though magnetometry using the “Vibrating
Magnetometer 7404 VSM” (Lake Shore Cryotronics Inc., USA) with magnetic
fields up to 13 kOe. The magnetometer’s sensitivity was 10 −7 emu which allowed
measuring the magnetic moment of samples weighing milligrams. The mass was
determined by the electronic microbalance AB135-S/FACT with auto-identification
(Mettler Toledo, Switzerland) which had a sensitivity of 10 −5 g.
20.2.3 Electron Spin Resonance (ESR) Spectroscopy
ESR spectra were recorded with the spectrometer R¨1307 at liquid nitrogen
temperatures (77 K) in a cylinder resonator with the mode H 011 and frequency
9.15 GHz. The power of microwave radiation was 40 mW, and the magnetic field
modulation frequency was 100 kHz. The samples were placed in a quartz Dewar
flask with an inner diameter of 4.5 mm.
20.3 Experimental Results
20.3.1 Magnetic Studies of Fe 3 O 4 Nanoparticles
The results of magnetic studies of magneto-mechano-chemically activated Fe 3 O 4
NPs are shown on Fig. 20.1 and Table 20.1.
The data analysis testifies that parameters of the samples exposed to various
vibration frequencies had a significant quantitative difference in comparison to the
sample exposed to ER only and the sample without any influence. The studies found
a negative correlation (r = −0.63) between the saturation magnetic moment m s
and vibration frequency f. It is known that the coercivity H c is the intensity of an
applied magnetic field required to reduce the magnetization of the material to 0
after the magnetization of the sample had been driven to saturation. Thus, coercivity
measures the resistance of a ferromagnetic material to demagnetization. The greater
the coercivity, the higher the specific absorption rate (SAR) of electromagnetic
field is detected [10]. In our experiments, all samples had low coercivity H c and a
small area of the hysteresis loop S that can be classified as soft magnetic materials.
The changes of coercivity H c and area of the hysteresis loop S in NPs after
magneto-mechano-chemically activation did not have any correlation with vibration
frequencies.