Osaka University, Japan
Kazuya Kikuchi graduated from the PhD course of the University of Tokyo (Japan) in 1994 and did his postdoctoral training at UCSD and the Scripps Research Institute. He was appointed as a research associate at the University of Tokyo (Japan) thereafter and promoted to associate professor. He was appointed as a full professor at Osaka University in 2005. During these period he became involved in molecular imaging probes development for both fluorescence imaging and magnetic resonance imaging. He is focused both in in vivo imaging and single molecule cellular imaging.
MRI (Magnetic Resonance Imaging) has been clinically used since it yields images of deep regions in living animal bodies. We have focused on 19F MRI. 19F MRI is suitable for monitoring particular signals concerning biological phenomena because 19F MRI shows little endogenous background signals. Thus, 19F MRI probes that can visualize biological functions have been increasingly reported. We have developed the 19F MRI probes to detect protease activity and gene expression on the basis of paramagnetic resonance enhancement (PRE) effect. We also have developed a novel 19F MRI contrast agent, fluorine accumulated silica nanoparticle for MRI contrast enhancement, which is composed of a perfluorocarbon core and a robust silica shell. Multifunctional mesoporous silica nanoparticles (MSNs) are good candidates for multimodal applications in drug delivery, bioimaging, and cell targeting. A novel drug delivery carrier based on MSNs, which encapsulated highly sensitive 19F magnetic resonance imaging (MRI) contrast agents inside MSNs, will be introduced. The nanoparticles were labeled with fluorescent dyes and functionalized with small molecule-based ligands for active targeting. This drug delivery system facilitated the monitoring of the biodistribution of the drug carrier by dual modal imaging (NIR/19F MRI). Furthermore, we demonstrated targeted drug delivery and cellular imaging by the conjugation of nanoparticles with folicacid. An anticancer drug (doxorubicin, DOX) was loaded in the pores of folate-functionalized MSNs for intracellular drug delivery. The release rates of DOX from the nanoparticles increased under acidic conditions, and were favorable for controlled drug release to cancer cells.