Page 220 - Computational Modeling in Biomedical Engineering and Medical Physics

Magnetic drug targeting 209

Figure 6.31 The dynamics of the MPNs transfer from the larger vessel to the target region (c max 5
c b )—species (contours), magnetic body forces. (A) t 5 500 s. (B) t 5 1000 s. (C) t 5 1170 s.

Eventually the tumor ROI is reached, due to the higher diffusivity of the MNPs
here, it is covered with almost uniform concentration of MD, increasing in time.
It may be inferred that the MD has to produce its curative effect faster than the
carrying MNPs leave to ROI to, eventually reach the magnet, because of the continu-
ing action of the magnetic motive force. And, again, the PM should be placed such
that the ROI is in between it and the larger vessel that advects the MD.
Eventually the MD at the vessel wall vanishes, and this entrains the extinction of
the magnetic field controlled delivery.
On closing, the synthesis of MNPs covers a wide range of compositions and tun-
able sizes, fabrication, and surface engineering involve complex chemical, physical, and
physicochemical multiple interactions. The promise of MNPs resides in natural prop-
erties of their superparmagnetic core combined with the drug loading capability and
the biochemical properties that they can be enodwed with by means of a
suitable coating. According to the current experience the polymer acts actually as the
principal material in MNPs design for drug delivery.
The MDT is using MNPs (SIONs) as representative entities medical or biologi-
cal purposes and, in numerical modeling their spatial distribution is usually consis-
tent with the continuous media assumptions. The magnetic field sources in MDT
are either permanent or coils. Time and space scales, couplings, which are typical
to multiphysics problems, are important in the multiscaling analysis, with the aim
to produce solvable numerical models consistent with the physics that they
represent.
In larger vessels that transfer the MD, depending on the magnetic field spectrum,
the magnetomotive forces may either enhance (accelerate) or oppose (decelerate) the
flow, and they may indirectly induce recirculation. If the MD is to cross the epithelial
membrane, the component of the MF force orthogonal to the streamwise flow is then
of interest.