Nanomedicine, by using nanoparticles (NPs) with varied physio-chemical architecture, has been introduced to clinics for cancer diagnosis via imaging as well as for tumor therapy, since the development of “Nanotechnology”. Nanotechnology engineers multifunctional devices with materials at dimensions of nano scales (10–9 meter), featuring to move detection signals and/or therapeutic NP cargo(s) for both therapy as well as diagnosis. The NPs are specially designed to reach safely to their target through nanomachines to the site of the disease, by enhancing the drug’s bioavailability. Moreover, the NPs have the ability for passive targeting in tumours. This phenomenon is called the “enhanced permeation as well as retention effect”, which initiates the leakage in the angiogenetic vessels having poor lymphatic drainage. Thus, polyethyleneglycol (PEG) is commonly used to protect the NPs from the endothelial cleavage, preventing the cellular uptake and its controlled intracellular drug release. Polymers, stealth liposomes and dendrimers are associated with a targeting ligand. Inorganic NPs like gold and iron oxide are coupled for successful cancer diagnostics and therapeutics. Thus, in this chapter the usage of peptides, peptones and proteins are specifically administered for intracellular trafficking as well as the targeted NPs for bioanalytical, bioimaging, drug delivery and therapeutic applications.