Fig. 5

Different stages in the development of novel tumour-targeted imaging agents. (1) Many approaches might be applied to highlight the tissue of interest. (2) The appropriate target selection should be combined with identifying a targeting agent/binder to interact with the target. In general, downsizing the binder shortened the half-life of the imaging agent in circulation, reducing background signal intensity. Synthetic binders, such as small molecules and nanoparticles, are appealing for active targeting because they may be modified using various chemical techniques. (3) The signal moiety generates the signal for imaging applications