Nanoscopic Agents in a Physiological Environment: The Importance of Understanding Their Characteristics

The application of nanotechnology in medicine signifies one of the most exciting developments in science over the last decade. Even though advancement has been made in nanoparticle engineering in terms of size, shape and surface functionalisation, the behaviour in vivo remains poorly characterised and understood. The potential impact of engineered nanomaterials on human health is strictly related to their behaviour in the biological environment. When in contact with biological fluids, nanoparticles spontaneously interact and adsorb proteins to dramatically change their surface properties. Thus, the nanoparticle surface acquires a new biological identity that will influence its stability and interaction with the cellular machinery, thereby affecting the nanoparticle biodistribution in vivo. This protein coating ‘expressed’ at the nanoparticle surface is what is ‘read’ by the cells. Consequently, methods to effectively study the structure and composition of this bio-nano interface have been emerging as key objectives in nanoscience. In this chapter, we discuss the state-of-the-art techniques for the physico-chemical characterisation of nanoparticle-protein complexes in the biological environment with particular emphasis on their impact on the efficiency and safety of a new generation of nanomedicines. We also highlight the barriers faced by nanomedicines for effective targeting and delivery in vivo.