Application of ceramic/polymer conjugate materials for near infrared biophotonics

Over-1000-nm (OTN) near infrared (NIR) wavelength region lying between 1000 and 1700 nm has been known as so-called "biological window" where the optical loss in live body is minimized. Recent development of InGaAs CCD cameras, which can visualize in the above wavelength region, is making it possible to visualize the biological or medical images in the OTN-NIR wavelength region. On the other hand, rare-earth doped ceramic nanophosphors (RED-CNP) is one of the fluorescent nano materials that can be applied for the fluorescence bioimaging in the OTN-NIR wavelength region. This paper will review the developments of the systems and materials for the OTN-NIR fluorescence bioimaging. As an example in the development of imaging system, the mouse brain stem was demonstrated to image by fluorescence imaging without opening the skin or skull of the mouse. As an example of materials' development, the synthesis and characterization of liposomes which contain Er- and Yb-doped Y ₂O ₃ or NaYF ₄ are reported along with the OTN-NIR in vivo fluorescence imaging by using them.