title: Intelligent design of nano-scale molecular imaging agents.
abstract: Visual representation and quantification of biological processes at the cellular and subcellular levels within living subjects are gaining great interest in life science to address frontier issues in pathology and physiology. As intact living subjects do not emit any optical signature, visual representation usually exploits nano-scale imaging agents as the source of image contrast. Many imaging agents have been developed for this purpose, some of which exert nonspecific, passive, and physical interaction with a target. Current research interest in molecular imaging has mainly shifted to fabrication of smartly integrated, specific, and versatile agents that emit fluorescence or luminescence as an optical readout. These agents include luminescent quantum dots (QDs), biofunctional antibodies, and multifunctional nanoparticles. Furthermore, genetically encoded  nano-imaging agents embedding fluorescent proteins or luciferases are now gaining popularity. These agents are generated by integrative design of the components, such as luciferase, flexible linker, and receptor to exert a specific on-off switching in the complex context of living subjects. In the present review, we provide an overview of the basic concepts, smart design, and practical contribution of recent nano-scale imaging agents, especially with respect to genetically encoded imaging agents.
authors.affiliation: Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba 305-8569, Japan. kimu-sb@aist.go.jp.
authors.forename: Sung Bae
authors.initials: SB
authors.lastname: Kim
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Hattori
authors.forename: Takeaki
authors.initials: T
authors.lastname: Ozawa
mesh_terms: D000818:Animals; D006801:Humans; D008164:Luminescent Proteins / Q000737:chemistry* / Q000494:pharmacology*; D057054:Molecular Imaging / Q000379:methods*; D061848:Optical Imaging / Q000379:methods*; D045663:Quantum Dots / Q000737:chemistry*
chemical_list: D008164:Luminescent Proteins