Page - (000393) - in Biomedical Chemistry: Current Trends and Developments

diagnostics approach than passive targeting imaging. To make it possible to biofunctionalize the SPIONs, it is necessary to provide them with a surface coating system in order to create a desirable platform for conjugation of targeting ligands or to make the SPIONs sensitive to tumor characteristic microenvironment (Fig. 3.5.13) (Jin, 2014; Xie, 2010). Figure 3.5.13: Schematic representation illustration of the polymer micelle composite system of surface-engineered SPION for imaging and therapy applications. Adapted from (Jin, 2014). Recently, several studies utilizing SPIONs for the active targeting of several types of cancer were conducted and showed promising results (Kievit, 2012; Ling, 2014; Melancon, 2011; Zhang, 2014a; Zhang, 2014c). “CLIO” nanoparticles, which are SPIONs cross-linked with a dextran coating, have appeared as a powerful multistage nanovector for targeted imaging and diagnostic applications, allowing a wide and versatile conjugation of targeting moieties and compatible with diagnostic imaging MRI, optical and PET techniques (Tassa, 2011). Imaging and diagnosis can be achieved with this nanoscaled platform, as well as the delivery of therapeutic cargos to the tumor sites, making multifunctional systems or “theranostic” (Choi, 2012). For example, in a recent study, CLIO nanoparticles were developed with the purpose of producing a multifunctional platform. Taking advantage of the eminent levels of MMPs in the tumor microenvironment, in particular MMP-14, which has an important role in the tumor invasion features and provides a direct cellular target for prodrug activation (Devy, 2009; Landry, 2005), it was found that functionalization of the CLIO nanoparticulate system with the MMP-14 cleavable peptide-conjugate of azademethylcolchicine leads to vascular collapse of the tumor (Reyes-Aldasoro, 2008). This theranostic nanovector provided an opportunity to image selectively the