The advancement of nanotechnology has boosted the development of new and modified medicine in treating various human diseases and disorders, particularly in cardiovascular diseases and cancers, which are the two main death-causing killers globally. Nanomaterials are defined as a material with sizes of 1 and 100 nm. Owing to the diverse properties and types of nanomaterials, there is a huge potential utilising them to modify and improve the current drugs and therapeutic strategies. These include enhancing drug effectiveness, increasing target specificity, improving drug stability and bioavailability, increasing body absorption, and minimising off-target cytotoxicity. To achieve the abovementioned drug activities, the responses of the targeted cells, tissues, organ and subsequently the organ system play important parts. Unquestionably, the drug responses could also largely be affected by the pathophysiology and surrounding micro-environments of the diseased models or organs. Vice versa, the drug payloads may also contribute to the alterations in the routine biological processes of the organs or may render toxicity to the target organ or organ systems. This chapter aims to discuss the current nano-systems used for drug delivery and target specificity as well as to provide insights to improve the drug selectivity, safety profile and therapeutic efficacies. The overview of this chapter is depicted in Fig. 11.1.