Chapter 9: Complement Activation

The complement system is the most important biochemical cascade in the blood for the recognition, opsonization, and elimination of foreign materials. To date, the leading causes of death in the United States include cancer, cardiovascular and neurodegenerative diseases, and diabetes. New treatments are urgently needed to treat these devastating diseases and nanotechnology potentially provides new avenues to fight such illnesses. These avenues include the development of novel nanocarriers that deliver drugs in a specific and controlled manner, while minimizing secondary effects. The success of bioengineering effective nanocarriers for drug delivery purposes requires a deep understanding of the interaction between the complement system and the nanocarriers. This review focuses on reporting the current state of complement activation by different nanomaterials. Here, we assess various important parameters that influence the activation of the complement system, which include the physicochemical characteristics of both nanocarriers and complement proteins. We next evaluate the most recent engineering approaches to prevent or reduce complement activation. Finally, we discuss different in vitro and in vivo procedures to assess complement activation.