ABSTRACT
NP-based radiopharmaceuticals can be broadly classied into two types: type A and type B (Figure 12.1). In type A nanoradiopharmaceuticals, radioisotopes are incorporated inside biodegradable NPs of organic matrices (Hamoudeh et al. 2007, 2008). For example, Hamoudeh and coworkers (2007, 2008) have shown that dirhenium decacarbonyl [Re2(CO)10] can be incorporated into biocompatible poly-l-lactide (PLLA) NPs. Rhenium-loaded PLLA NPs, upon exposure to neutron irradiation, result in the generation of radioactive rhenium, which subsequently can be used for cancer therapy (Hamoudeh et al. 2007, 2008). e group
has shown that the structural integrity of rhenium carbonyl is maintained aer exposure to neutron irradiation. Type B NPs are derived from direct doping of radioisotopes into an inorganic NP matrix. In this type, radioisotopes become an integral part of the nanoparticulate matter. Type B nanoparticulates consist of radioisotopes generated in an inorganic nanomatrix, and that can, subsequently, be surface-conjugated to antibodies, peptides, or proteins (Woodward et al. 2011). For example, Actinium-225 can be incorporated into a LaPO4 NP matrix. Decay of 225Ac results in stable 209Bi, with release of four α-particles. e study further shows a retention of ~50% of daughter nuclides within the La(225Ac)PO4 NPs over a period of 1 month (Woodward et al. 2011). In a similar fashion, therapeutic 198Au NPs can be incorporated within the nonradioactive gold nanoparticle (AuNP) matrix to yield [198AuAuNP] NPs (Kannan et al. 2006; Chanda et al. 2010a). ese radioactive gold NPs have shown excellent therapeutic properties in animal models (Chanda et al. 2010b). In fact, recent publications from around the globe oer a wealth of information on how radioactive gold NPs can aid in the therapy of cancer (Chanda et al. 2010b; Kannan et al. 2012). is chapter will summarize the recent advances in radioactive gold NP-based cancer therapy, the inherent advantages of radioactive gold, and the future prospects of NPs in clinical applications. Recent advances in the synthesis of radioactive gold NPs and their applications in cancer therapy are discussed below.
