Nanotechnology access to most tissues. The nanoparticle uptake

Nanotechnology has an important role in the medical field. Recently,
magnetic nanoparticles (mNPs) have become essential tools in molecular
diagnosis, in vivo imaging and treatment of disease, and the major aim being
the production of a more theranostic approach. Since they are small in size,
the nanoparticles can cross most of the barriers like the blood brain barrier,
the blood vessels, thus providing effortless access to most tissues. The nanoparticle
uptake must be maximum to treat any disease. A new method like association of
mNPs with peptides which penetrate the cells to allow the excellent
translocation of haul into the cell and by using an external magnetic field to facilitate
its delivery is under study. There can be many inventions in the use of
magnetic particles since their physical and magnetic properties, surface
coatings can be changed as per one’s desires. The uniqueness in their use is
that, for mechanotherapy, the particle diameters are of the same length as the
biological cells that need to be cross-examined. Most important is that, there
is not much loss of their magnetization even at the nanoscale. They can be
synthesized with their diameter being only a few nanometers, but can still
achieve satisfactory uniformity in dimensions within a batch. At this size,
each particle has only a single magnetic domain and super paramagnetic
properties, as compared to the larger magnetic particles, which have multiple
ferromagnetic domains and permanent magnetic properties. The external magnetic
field exerts a force which ranges from 10-12 to 10-9 newtons on the particle,
which are the common levels experienced by the cells in the body. For
mechanotherapeutic studies, particles made up from iron oxide have more often
usage than other magnetic materials like cobalt or nickel since they are easier
to synthesize from iron salts by the co-precipitation method. Batches of pre-synthesized
iron oxide micro- or nanoparticles are commercially available, from the manufacturers
with reactive functional groups on the surface as required for the purpose to
be used for. It is now possible to attach a ligand by using chemical methods
after deciding the surface functional group, enabling it to bind to the
appropriate receptor on the cell surface. But, a more uncomplicated method is
by using the hydrophobic interactions to adsorb the matrix proteins from the
solution. Proteins like collagen or fibronectin have their original
conformation intact when adsorbed, and so cells bind through their receptors’ that
recognize the protein’s ligand domains which are still intact. A major concern,
is the biological compatibility of the materials used, so iron oxide is more
favorable to use than cobalt or nickel as iron homeostasis is controlled by the
cell to flush excessive iron. Many attractive possibilities have aroused in the
biomedical field. One can control their sizes ranging from a few nanometers up
to tens of nanometers, due to which, their dimensions are smaller than or
comparable to those of a cell (10–100µm), a virus (20–450 nm), a protein (5–50
nm) or a gene (2 nm).

This shows their possibility of getting nearly
close to a biological entity of one’s interest. Nevertheless, coating with a
suitable biological molecule to help them bind to specific cell, thereby
provides a means of regulating it in the body. Since, the nanoparticles are
magnetic, they obey Coulomb’s law, and can be controlled by an external
magnetic field. This ‘action from outside the body’, combined with the
intrinsic penetration of magnetic nanoparticle into the human tissue, is
opening up many new uses like the movability and/or immobilization of magnetic
nanoparticles. Hence, they can be made to deliver an anticancer drug, or a
cluster of radionuclide atoms, to a targeted part of the body, for example, a tumor.
The magnetic nanoparticles can be designed in a such a way that they show some response
to a time-varying magnetic field, with highly attractive results which can be related
to the energy transfer from an already excited field to the nanoparticle. For
example, when the particle is heated, it leads to their use as hyperthermia
agents, which can be used to deliver lethal amounts of thermal energy to tumors
which can act as targeted regions; or as chemotherapeutic and radio therapeutic
enhancement agents, where even a medium level of tissue warming is effective in
malignant cell destruction.