Protein Interactions with Microballoons: Consequences for Biocompatibility and Application as Contrast Agents

The role of proteins as the mediators of the interaction between engineered materials (biomaterials) and living systems has long been appreciated, but the subtleties and complexities introduced by changing surface curvature are only beginning to be understood. Thus, in implant devices, where the biomaterial is presented as a flat surface, a very limited range of proteins bind to the material, these being mainly albumin and fibrinogen. However, as the surface curvature increases (as we move towards micro and nano scale particles) novel effects are observed, and the materials begin to bind rarer specialized proteins with very high affinity, which has significant consequences for their biocompatibility and for their impacts on the biological system with which they interact. In the present work we present some findings from the EU project SIGHT in which the interactions of polymeric microballoons (gas-filled polymer-shelled devices that are being developed as contrast agents for theranostic applications) with plasma proteins are investigated, and the potential consequences for long term biocompatibility are discussed.