Biocompatible ZnS capped CdSe fluorescent semiconductor nanocrystals (quantum dots, QDs) exhibit great potential as imaging agents with biomedical and clinical relevance. However, little is known about the fate of the quantum dots in vivo , and the importance of chemical and physical composition that may influence their behavior in vivo . When the QDs are introduced in vivo , the first interactions with blood components will dictate their kinetic behavior in vivo . We present some preliminary results that demonstrate the interactions of the quantum dots with plasma proteins and that quantum dots can be trapped in fibrous networks.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.