of the surrounding medium [159]. With this inherent characteristic, CuS NPs are
able to absorb light in the NIR region and directly convert it to thermal energy to be
used in thermal ablation of tumor cells. Recently, CuS NPs, with advantages of high
stability and high photothermal conversion efficiency, are being highlighted as
promising multifunctional agents that can integrate both imaging and therapy
[160]. More specifically for nuclear imaging, a prudent approach to utilize low
specific activity
64 Cu for PET imaging is to synthesize intrinsically radiolabeled
NPs using a radioactive precursor (
64 CuCl 2 solution). Adopting this strategy,
64 Cu
atoms are built inside the crystal lattice of the normal nanocrystals, resulting in high
radiochemical stability. Intrinsically radiolabeled
64 CuS NPs are one such class of
nanoplatforms, which can easily be prepared by metathesis reaction of
64 CuCl 2 and
Na 2 S. The simplicity of the procedure allows synthesis of clinically relevant doses
of the radioactive
64 CuS NPs in an adequately shielded facility with minimum
radiation exposure to the personnel involved [161]. Zhou et al. [162], for instance,
synthesized *11 nm diameter [
64 Cu]CuS NPs to be used not only for PET/CT
imaging but also for photothermal ablation purposes. PEGylated [
64 Cu]CuS NPs,
exhibited high radiolabeling efficiency and stability, even without the use of any
chelators. A high tumor uptake was found for these NPs in a U87MG human
glioblastoma tumor model, as a result of passive targeting (Fig. 2.7c). Signs of
hyperthermia-induced necrosis (e.g., loss of nucleus, cell shrinkage etc.) were seen
in tumor tissue as a consequence to NIR laser irradiation. In general, this
proof-of-concept study revealed the potential of CuS NPs to act as a promising
multifunctional moiety for image-guided photothermal ablation of cancer [162].
2.6.4 Others
Zinc oxide (ZnO) NPs of a wide variety of nanostructures and miscellaneous
semiconducting, optical, and piezoelectric properties, have also been used for
biomedical purposes, especially due its the low toxicity and biodegradability
property, as Zn
2+ itself is an intrinsic element in a healthy adult involved in various
involved in various aspects of metabolism [163]. Owing to its intrinsic fluorescence, ZnO NPs have been used for not only optical imaging [164], but also for
bioimaging techniques such as MRI [165] and PET [166]. Novel red fluorescent
ZnO NPs were developed by Hong et al. [166] followed by successful conjugation
of
64 Cu and TRC105 to these ZnO NPs. PET scans following the injection of [
64 Cu]
NOTA–-ZnO–PEG–TRC105 in 4T1 tumor-bearing mice revealed a high radioactivity accumulation in the tumor, liver, and the abdominal area. However, other
tissues exhibited negligible accumulation leading to good tumor imaging contrast
[166].
Recently, a few groups have found that atomically thin transitional metal
dichalcogenides (TMDCs) nanosheets are also promising in the biomedical field
[167]. Chou et al. discovered that sulfur-terminated molecules could be used to
modify MoS 2 nanosheets to acquire better physiological stability and
2 Exogenous Radionanomedicine: Inorganic Nanomaterials
33
able to absorb light in the NIR region and directly convert it to thermal energy to be
used in thermal ablation of tumor cells. Recently, CuS NPs, with advantages of high
stability and high photothermal conversion efficiency, are being highlighted as
promising multifunctional agents that can integrate both imaging and therapy
[160]. More specifically for nuclear imaging, a prudent approach to utilize low
specific activity
64 Cu for PET imaging is to synthesize intrinsically radiolabeled
NPs using a radioactive precursor (
64 CuCl 2 solution). Adopting this strategy,
64 Cu
atoms are built inside the crystal lattice of the normal nanocrystals, resulting in high
radiochemical stability. Intrinsically radiolabeled
64 CuS NPs are one such class of
nanoplatforms, which can easily be prepared by metathesis reaction of
64 CuCl 2 and
Na 2 S. The simplicity of the procedure allows synthesis of clinically relevant doses
of the radioactive
64 CuS NPs in an adequately shielded facility with minimum
radiation exposure to the personnel involved [161]. Zhou et al. [162], for instance,
synthesized *11 nm diameter [
64 Cu]CuS NPs to be used not only for PET/CT
imaging but also for photothermal ablation purposes. PEGylated [
64 Cu]CuS NPs,
exhibited high radiolabeling efficiency and stability, even without the use of any
chelators. A high tumor uptake was found for these NPs in a U87MG human
glioblastoma tumor model, as a result of passive targeting (Fig. 2.7c). Signs of
hyperthermia-induced necrosis (e.g., loss of nucleus, cell shrinkage etc.) were seen
in tumor tissue as a consequence to NIR laser irradiation. In general, this
proof-of-concept study revealed the potential of CuS NPs to act as a promising
multifunctional moiety for image-guided photothermal ablation of cancer [162].
2.6.4 Others
Zinc oxide (ZnO) NPs of a wide variety of nanostructures and miscellaneous
semiconducting, optical, and piezoelectric properties, have also been used for
biomedical purposes, especially due its the low toxicity and biodegradability
property, as Zn
2+ itself is an intrinsic element in a healthy adult involved in various
involved in various aspects of metabolism [163]. Owing to its intrinsic fluorescence, ZnO NPs have been used for not only optical imaging [164], but also for
bioimaging techniques such as MRI [165] and PET [166]. Novel red fluorescent
ZnO NPs were developed by Hong et al. [166] followed by successful conjugation
of
64 Cu and TRC105 to these ZnO NPs. PET scans following the injection of [
64 Cu]
NOTA–-ZnO–PEG–TRC105 in 4T1 tumor-bearing mice revealed a high radioactivity accumulation in the tumor, liver, and the abdominal area. However, other
tissues exhibited negligible accumulation leading to good tumor imaging contrast
[166].
Recently, a few groups have found that atomically thin transitional metal
dichalcogenides (TMDCs) nanosheets are also promising in the biomedical field
[167]. Chou et al. discovered that sulfur-terminated molecules could be used to
modify MoS 2 nanosheets to acquire better physiological stability and
2 Exogenous Radionanomedicine: Inorganic Nanomaterials
33