Page - (000392) - in Biomedical Chemistry: Current Trends and Developments

The employment of nanoparticulate systems to image and diagnose cancer has been extensively applied and new approaches have been developed (Choi, 2012). Some advantages of using nanoparticulate- based probes for imaging purposes is attained to their low cytotoxicity profiles and physicochemical properties (Santos, 2013a). In general, a surface area-to-volume ratio and effective surface functionality, are particularities used as tools to tune the nanoparticle properties for tissue or cell targeting in vivo through high affinity to certain cell biomarkers (Davis, 2008). Biochemical changes in vivo, such as enhanced receptor density in a certain tumor type could be imaged and measured by probing with specific nanoparticulate systems avid to bind to it (Jin, 2014; Satpathy, 2015). These probes shall attain certain features that allow them to be detected and promote their accumulation at the site of interest, be safe and biocompatible, as well as to have limited side effects and to avoid the hostile environments encountered in vivo, such as avoidance of interactions with plasma proteins and the recognition by the phagocytic cells and consequent removal from the systemic circulation by the mononuclear phagocyte system (Santos, 2013a). For example, superparamagnetic iron oxide nanoparticles (SPIONs), along with many other clinical applications, are some of the nanoparticulate systems that are most used as highly effective contrast agents for MRI diagnosis of solid tumors (Ittrich, 2013; Rosen, 2012). Compared to other traditional contrast agents, SPIONs exhibit several advantageous properties, among them the greater magnetic signal strength and longer lasting contrast enhancement, low cytotoxic effects, biodegradability and improved delineation of tumor margins (Corot, 2006; Varallyay, 2002; Wang, 2001). Such nanoparticulate systems have been used to target solid tumors, either in a passive way, (Zolata, 2014), taking advantage of the leaky and damaged tumor vasculature through the enhanced permeability and retention effect (Brannon-Peppas, 2004; Rosen, 2012), by targeting actively the tumor sites by attaching a targeting ligand to the surface of the SPIONs, or by taking into account the tumor pathological features, such its lower pH microenvironment. The internalization of SPIONs enables a longer and effective imaging time by improvement of the contrast-enhancing effect of the particles through the accumulation of a high number of SPIONs in the tumor tissue, therefore being a more promissing and sensitive molecular