Gold Nanoparticles

Several studies have documented the applications of gold nanoparticles in PET/CT imaging [76—79]. These particles are labeled with radioactive agents such as positron or gamma emitters. This approach exploits the sensitive nature of PET combined with the accuracy of CT in localization. Morales-Avila et al. documented the efficacy of 99-m technetium gold nanoparticles conjugated to RGD peptides for imaging metastatic tumor. This non-invasive study conducted in C6 human glioma tumor-bearing athymic mice demonstrated high specificity in imaging tumor avb3 expression [80]. The integrin’s role in tumor metastasis and angiogenesis has been documented. This target-specific approach may be a potential tool for oncologists to design highly effective individualized therapeutic regimen for patients with cancer.

Gold Nanoshells

Gold nanoshells (NS) are spherical nanoparticles comprising a dielectric core and a metal shell. The plasmon resonance frequency is determined by the relative size of the core and the metal shell [81]. The unique size, shape, and optical properties of the gold NS render these shells ideal candidate for cancer detection and treatment. Xie et al. studied a radiolabeled gold nanoshell. This construct was injected into nude mice induced with head and neck squamous carcinoma xenograft. PET/CT imaging revealed accumulation of 64Cu-labeled nanoparticles in the tumor site 20 and 40 h after injection. This construct was labeled with PEG2k-DOTA for chelation of Cu64 and surface modification, to a diameter of 174 nm and surface charge of —5 mV [82]. The authors obtained high radiolabeling efficiency (81.3%), stability (3 h), and high-resolution PET images [82].

Shao et al. reported the efficacy of I-125-labeled gold nanorods (NR) in arthritic- induced mice. These nanorods were conjugated with anti-intercellular adhesion molecule 1 antibody, which is overexpressed in arthritic disease. PEGylation of gold NR resulted in longer circulation time. It leads to higher accumulation at inflamed joints yielding better treatment [83].

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