330
V. Orel et al.
In our experiments under fixed frequency vibration during magneto-mechanochemical synthesis, we had differences in the magnetic memory response for
conventional iron oxide NPs (Fe 3 O 4 ) and nanocomplex from the core (Fe 3 O 4 ) –
shell (oxide film and DOXO). It may be assumed that the difference in the magnetic
memory response is related to the spin-dependent radical pair states on the surface
layers of conventional iron oxide NPs and NPs loaded with DOXO. The magnetic
memory effect originates from the interaction of a magnetically ordered layer in the
magnetite shell and the spins located at the interface Fe 3 O 4 /DOXO.
This can be explained with well-known effect of the Zeeman spectral line
splitting on several components for paramagnetic centers (free radicals) in the
presence of a constant magnetic field. Then a resonant radio-frequency irradiation
under fixed vibration frequency can cause the transition from one electron spin state
to another switching between a spin forbidden, nonreactive triplet spin state of a
radical pair and a spin-allowed, chemically reactive singlet state [12, 13]. These
phenomena are based on the magnetic nuclear and electron spin resonance [14].
The probability of a transition between singlet and all three triplet states of the
radical pair under the influence of an electromagnetic field H i (τ), associated with
electronic transitions during resonance, could be determined by modified equation
[15]:
P =
1
2
gβ
2
H 2
1 (τ )
1 + (gβ/)
2
H 0 − H res
0
2 ,
(3)
where g is Lande g-factor, β is the Bohr magneton, H 0 is the external constant
magnetic field strength, H 0 is the external resonance constant magnetic field
strength, H i is the external resonance electromagnetic field strength, τ is the lifetime
of a radicals pair, and is the reduced Planck constant.
Ability to control the concentration of paramagnetic centers via mechanical,
magnetic, and electromagnetic can help to increase the activity, concentration, and
lifetime of paramagnetic centers (free radicals), which might cause oxidative stress,
genetic mutation, and/or apoptosis of tumor cells [16].
20.5 Conclusion and Future Perspectives
This paper shows the impact of combined mechanical vibration and electromagnetic
irradiation on the magnetic memory effect during the magneto-mechano-chemical
synthesis of the AMNC. This research opens the future way for remote control of
redox reactions within the tumor based on the magnetic memory effect in AMNC
without changing standard treatment doses for widely used chemotherapeutic
agents. Furthermore, limitation side effects of magnetic nanoparticle hyperthermia
[17] associated with high temperature may be avoided in clinical practices due to
decreased upper temperatures reached by the proposed approach in the treatment of
deep-seated malignant tumors.
V. Orel et al.
In our experiments under fixed frequency vibration during magneto-mechanochemical synthesis, we had differences in the magnetic memory response for
conventional iron oxide NPs (Fe 3 O 4 ) and nanocomplex from the core (Fe 3 O 4 ) –
shell (oxide film and DOXO). It may be assumed that the difference in the magnetic
memory response is related to the spin-dependent radical pair states on the surface
layers of conventional iron oxide NPs and NPs loaded with DOXO. The magnetic
memory effect originates from the interaction of a magnetically ordered layer in the
magnetite shell and the spins located at the interface Fe 3 O 4 /DOXO.
This can be explained with well-known effect of the Zeeman spectral line
splitting on several components for paramagnetic centers (free radicals) in the
presence of a constant magnetic field. Then a resonant radio-frequency irradiation
under fixed vibration frequency can cause the transition from one electron spin state
to another switching between a spin forbidden, nonreactive triplet spin state of a
radical pair and a spin-allowed, chemically reactive singlet state [12, 13]. These
phenomena are based on the magnetic nuclear and electron spin resonance [14].
The probability of a transition between singlet and all three triplet states of the
radical pair under the influence of an electromagnetic field H i (τ), associated with
electronic transitions during resonance, could be determined by modified equation
[15]:
P =
1
2
gβ
2
H 2
1 (τ )
1 + (gβ/)
2
H 0 − H res
0
2 ,
(3)
where g is Lande g-factor, β is the Bohr magneton, H 0 is the external constant
magnetic field strength, H 0 is the external resonance constant magnetic field
strength, H i is the external resonance electromagnetic field strength, τ is the lifetime
of a radicals pair, and is the reduced Planck constant.
Ability to control the concentration of paramagnetic centers via mechanical,
magnetic, and electromagnetic can help to increase the activity, concentration, and
lifetime of paramagnetic centers (free radicals), which might cause oxidative stress,
genetic mutation, and/or apoptosis of tumor cells [16].
20.5 Conclusion and Future Perspectives
This paper shows the impact of combined mechanical vibration and electromagnetic
irradiation on the magnetic memory effect during the magneto-mechano-chemical
synthesis of the AMNC. This research opens the future way for remote control of
redox reactions within the tumor based on the magnetic memory effect in AMNC
without changing standard treatment doses for widely used chemotherapeutic
agents. Furthermore, limitation side effects of magnetic nanoparticle hyperthermia
[17] associated with high temperature may be avoided in clinical practices due to
decreased upper temperatures reached by the proposed approach in the treatment of
deep-seated malignant tumors.