Seite - (000370) - in Biomedical Chemistry: Current Trends and Developments

Figure 3.5.9: 2D micro-PET cross-sections images, created using a filtered back-projection, of mice bearing a DLD-1 tumor (n = 3) at 36 h post-injection of 70 (A), 100 (B), and 160 nm (C) 64Cu- labeled Dox-SMNPs. Each image was scaled to its own maximum. The 70 nm Dox-SMNPs show the highest tumor-specific uptake among the three studies. Abbreviations: Dox-SMNPs, doxorubicin-loaded supramolecular magnetic nanoparticles. Adapted and reproduced with permission from (Lee, 2013b). Similarly to the size, the surface charge of nanoparticles exert an effect on their behavior in the systemic circulation, including the circulation time, interaction with elements of the RES and predisposition for interacting with the tumor cells, affecting cellular association and internalization (Alexis, 2008; He, 2010). In this regard, positively charged nanocarriers are recognized as owing more propensity for interacting and, consequently, accumulating at the tumor tissues, as suggested by studies performed in animal models (He, 2010; Hu- Lieskovan, 2005). An enhanced interaction between positively charged nanoparticles and the endothelial cells of the tumor microvasculature is suspected to be one of the mechanisms involved on the referred predisposition, and the application of this phenomenon on the targeting of the endothelium of the tumor vasculature for delivery of antiangiogenic agents has already been explored (Fasol, 2012; Lohr, 2012; Schmitt-Sody, 2003; Strieth, 2008). The coating of nanodelivery systems with hydrophilic polymers, such as PEG, has been widely used for improving biocompatibility, as well as for sterically stabilizing the nanocarriers (Alexis, 2008; Otsuka, 2003; Torchilin, 2006). The so-called PEGylation of the nanoparticles’