5.1 Introduction
Organic nanoparticles (NPs) are made of organic molecules. Natural organic
molecules may exist in 1–1000 nm in diameter which are proteins aggregates, lipid
bodies, milk emulsions, viruses, antibodies, albumin and etc. Organic NPs are also
produced as a form of food, cosmetics and pharmaceuticals. Pharmaceutical formulations are including liposomes, albumin, dendrimer, polymers and their conjugate forms [1].
Organic NPs as a drug delivery system have a relative long history of development and many of them are now approved for commercial use. The nano-carrier
used for drug delivery should be eliminated from the body, either by degradation or
by excretion. Many inorganic nano-carriers are very stable and difficult to metabolize, so they could be deposited in the body for long time [2]. Thus, biodegradable
nanomaterials are preferred for drug delivery which needs to improve solubility,
extend the half-life, and reduce toxicity. In this chapter, we dealt with four different
groups of biodegradable organic NPs as nano drugs: liposomes, albumin-based
NPs, dendrimers, and polymeric NPs.
Radiolabeling of biomolecules enables tracing these molecules in vivo.
Biodistribution and autoradiography studies validate tissue distribution of the
nano-carriers in animals. Nuclear medicine imaging such as single photon emission
computed tomography (SPECT) or positron emission tomography (PET) allows
non-invasive longitudinal monitoring of the in vivo pharmacokinetics and tissue
distribution of the nano-carriers even in human subjects.
In vivo tracking of nano-carriers using radionuclide imaging techniques enables
a theranostic approach as well, not just being a drug carrier. The combination of
diagnostic and therapeutic capabilities in a single drug delivery system can be used
for personalized precision therapies. In vivo imaging of radiolabeled NPs prior to
therapy has a function of companion diagnostics to predict accumulation of NPs at
target sites. This predicts the potential therapeutic response and enable to select
appropriate patients and to determine the dose to obtain an optimal therapeutic
response. The therapeutic NPs can be administered, if the radiolabeled NPs are
accumulated in the target tissues sufficiently determined by prior in vivo imaging.
Biodistribution of tracing dose of drug is not always the same as that of therapeutic
dose. During the radioiodine therapy of thyroid cancer, sometimes imaging after
therapeutic dose shows more metastatic lesions than diagnostic imaging. So,
drug-loaded NPs can also be radiolabeled to verify their delivery to the tissue of
interest for monitoring in the initial or following occasions of treatment. Insufficient
accumulation of the NPs on the target could explain a lack of therapeutic response.
Increased accumulation of the NPs on the normal organs predict the adverse effects.
Thus, radionuclide imaging of NPs can play an important role in the management of
the individual patients in each session of treatment.
Nano-drug delivery system has the long biologic half-lives, typically in the order
of days. It is essential to select radioisotopes with long half-life for following-up
imaging to evaluate the effective therapy. For nuclear medicine planar imaging or
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K. W. Kang and M. G. Song
Organic nanoparticles (NPs) are made of organic molecules. Natural organic
molecules may exist in 1–1000 nm in diameter which are proteins aggregates, lipid
bodies, milk emulsions, viruses, antibodies, albumin and etc. Organic NPs are also
produced as a form of food, cosmetics and pharmaceuticals. Pharmaceutical formulations are including liposomes, albumin, dendrimer, polymers and their conjugate forms [1].
Organic NPs as a drug delivery system have a relative long history of development and many of them are now approved for commercial use. The nano-carrier
used for drug delivery should be eliminated from the body, either by degradation or
by excretion. Many inorganic nano-carriers are very stable and difficult to metabolize, so they could be deposited in the body for long time [2]. Thus, biodegradable
nanomaterials are preferred for drug delivery which needs to improve solubility,
extend the half-life, and reduce toxicity. In this chapter, we dealt with four different
groups of biodegradable organic NPs as nano drugs: liposomes, albumin-based
NPs, dendrimers, and polymeric NPs.
Radiolabeling of biomolecules enables tracing these molecules in vivo.
Biodistribution and autoradiography studies validate tissue distribution of the
nano-carriers in animals. Nuclear medicine imaging such as single photon emission
computed tomography (SPECT) or positron emission tomography (PET) allows
non-invasive longitudinal monitoring of the in vivo pharmacokinetics and tissue
distribution of the nano-carriers even in human subjects.
In vivo tracking of nano-carriers using radionuclide imaging techniques enables
a theranostic approach as well, not just being a drug carrier. The combination of
diagnostic and therapeutic capabilities in a single drug delivery system can be used
for personalized precision therapies. In vivo imaging of radiolabeled NPs prior to
therapy has a function of companion diagnostics to predict accumulation of NPs at
target sites. This predicts the potential therapeutic response and enable to select
appropriate patients and to determine the dose to obtain an optimal therapeutic
response. The therapeutic NPs can be administered, if the radiolabeled NPs are
accumulated in the target tissues sufficiently determined by prior in vivo imaging.
Biodistribution of tracing dose of drug is not always the same as that of therapeutic
dose. During the radioiodine therapy of thyroid cancer, sometimes imaging after
therapeutic dose shows more metastatic lesions than diagnostic imaging. So,
drug-loaded NPs can also be radiolabeled to verify their delivery to the tissue of
interest for monitoring in the initial or following occasions of treatment. Insufficient
accumulation of the NPs on the target could explain a lack of therapeutic response.
Increased accumulation of the NPs on the normal organs predict the adverse effects.
Thus, radionuclide imaging of NPs can play an important role in the management of
the individual patients in each session of treatment.
Nano-drug delivery system has the long biologic half-lives, typically in the order
of days. It is essential to select radioisotopes with long half-life for following-up
imaging to evaluate the effective therapy. For nuclear medicine planar imaging or
106
K. W. Kang and M. G. Song