title: Clearance properties of nano-sized particles and molecules as imaging agents: considerations and caveats.
abstract: Nanoparticles possess enormous potential as diagnostic imaging agents and hold promise for the development of multimodality agents with both imaging and therapeutic capabilities. Yet, some of the most promising nanoparticles demonstrate prolonged tissue retention and contain heavy metals. This presents serious concerns for toxicity. The creation of nanoparticles with optimal clearance characteristics will minimize toxicity risks by reducing the duration of exposure to these agents. Given that many nanoparticles possess easily modifiable surface and interior chemistry, if nanoparticle characteristics associated with optimal clearance from the body were well established, it would be feasible to design and create agents with more favorable clearance properties. This article presents a thorough discussion of the physiologic aspects of nanoparticle clearance, focusing on renal mechanisms, and provides an overview of current research investigating clearance of specific types of nanoparticles and nano-sized macromolecules, including dendrimers, quantum dots, liposomes and carbon, gold and silica-based nanoparticles.
authors.affiliation: Molecular Imaging Program, NCI/NIH Building 10, Bethesda, MD 20892-1088, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Longmire
authors.forename: Peter L
authors.initials: PL
authors.lastname: Choyke
authors.forename: Hisataka
authors.initials: H
authors.lastname: Kobayashi
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D050091:Dendrimers; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods*; D006046:Gold / Q000737:chemistry; D006801:Humans; D007668:Kidney / Q000473:pathology*; D008081:Liposomes / Q000737:chemistry; D008099:Liver / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D053768:Metal Nanoparticles / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D045663:Quantum Dots; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D050091:Dendrimers; D008081:Liposomes; D037742:Nanotubes, Carbon; D011108:Polymers; D006046:Gold; D012822:Silicon Dioxide