LET radiation was found to be independent of the dose rate and also independent of
oxygenation [11, 12]. Alpha emitters have high energy, but their path length are
intermediate, merely corresponding to the diameter of several cells [12]. Therefore,
their intermediate particle range and high LET radiation make alpha emitters
suitable candidates for the treatment of blood or bone marrow malignancies, as well
as for small solid tumors and metastases. Lastly, Auger electron emitters have
relatively high LET radiation presenting with low toxicity compared with alpha
emitters, but they are only suited for hitting a blow to single tumor cell. To exert
radiobiological effects of Auger electrons, they must penetrate the cytoplasm and
then reach the nucleus since their ranges in tissues are very short. For this reason,
Auger electron emitters are not desirable as therapeutics in clinical practice.
23.3 Radiolabeled Nanoparticles for Therapeutic/
Theranostic Use
Nanoparticles are defined as materials that have at least one dimension in the range
of 10–100 nm. NPs have novel properties that distinguish them from the bulk
material. In addition to intrinsic properties of NPs, chemical and physical versatility
of NPs could also be exploited to develop drugs for diagnostics and therapeutics.
NPs could even be designed as multimeric systems to produce multivalent effects,
because functionalization of NPs by conjugating biomolecules to their surfaces
makes them target the receptors on the cancer cell surfaces. Moreover, functionalized NPs with various linkers are able to function as carriers for drugs, genes, and
others. Micelles and liposomes, potential platforms for carrying therapeutics such as
cytotoxic drugs, genes, or radionuclides, have already been used for cancer treatment in clinical practice. Various NPs such as gold nanoparticles, single-walled
carbon nanotubes, quantum dots or iron oxide nanoparticles once labeled with
beta-particle emitters, represent unique, multifunctional and target-specific radiopharmaceuticals functioning simultaneously as radiotherapy, thermal ablation and
multimodal imaging systems. In this regard, NPs have emerged as clinically relevant platforms, and NPs labeled with therapeutic radionuclides can also be used as
in vivo theranostics.
NPs labeled with therapeutic radionuclides have been proposed as a new class of
therapeutics. In particular, multifunctionalized NP platforms are useful for taking
advantages of already established radionuclide therapy (Fig. 23.3). The multifunctional NPs have the potential to carry high levels of radioactivity per particle by
using various linkers and functionalization. Utilizing this advantage, the therapeutic
effect of radiolabeled NPs could be maximized via multimeric receptor-specific
biomolecules interactions. Utilizing this multifunctionality, the radiolabeled NPs
conjugated with different targeting probes could be useful, since it can maximize
therapeutic effects through targeted radiotherapy as well as other type of
therapeutics.
23 Therapeutic/Theranostic Use of Radionanomedicine
435
oxygenation [11, 12]. Alpha emitters have high energy, but their path length are
intermediate, merely corresponding to the diameter of several cells [12]. Therefore,
their intermediate particle range and high LET radiation make alpha emitters
suitable candidates for the treatment of blood or bone marrow malignancies, as well
as for small solid tumors and metastases. Lastly, Auger electron emitters have
relatively high LET radiation presenting with low toxicity compared with alpha
emitters, but they are only suited for hitting a blow to single tumor cell. To exert
radiobiological effects of Auger electrons, they must penetrate the cytoplasm and
then reach the nucleus since their ranges in tissues are very short. For this reason,
Auger electron emitters are not desirable as therapeutics in clinical practice.
23.3 Radiolabeled Nanoparticles for Therapeutic/
Theranostic Use
Nanoparticles are defined as materials that have at least one dimension in the range
of 10–100 nm. NPs have novel properties that distinguish them from the bulk
material. In addition to intrinsic properties of NPs, chemical and physical versatility
of NPs could also be exploited to develop drugs for diagnostics and therapeutics.
NPs could even be designed as multimeric systems to produce multivalent effects,
because functionalization of NPs by conjugating biomolecules to their surfaces
makes them target the receptors on the cancer cell surfaces. Moreover, functionalized NPs with various linkers are able to function as carriers for drugs, genes, and
others. Micelles and liposomes, potential platforms for carrying therapeutics such as
cytotoxic drugs, genes, or radionuclides, have already been used for cancer treatment in clinical practice. Various NPs such as gold nanoparticles, single-walled
carbon nanotubes, quantum dots or iron oxide nanoparticles once labeled with
beta-particle emitters, represent unique, multifunctional and target-specific radiopharmaceuticals functioning simultaneously as radiotherapy, thermal ablation and
multimodal imaging systems. In this regard, NPs have emerged as clinically relevant platforms, and NPs labeled with therapeutic radionuclides can also be used as
in vivo theranostics.
NPs labeled with therapeutic radionuclides have been proposed as a new class of
therapeutics. In particular, multifunctionalized NP platforms are useful for taking
advantages of already established radionuclide therapy (Fig. 23.3). The multifunctional NPs have the potential to carry high levels of radioactivity per particle by
using various linkers and functionalization. Utilizing this advantage, the therapeutic
effect of radiolabeled NPs could be maximized via multimeric receptor-specific
biomolecules interactions. Utilizing this multifunctionality, the radiolabeled NPs
conjugated with different targeting probes could be useful, since it can maximize
therapeutic effects through targeted radiotherapy as well as other type of
therapeutics.
23 Therapeutic/Theranostic Use of Radionanomedicine
435