Hidetaka Akita

Design of Smart Nano Device for Intracellular Targeting

To obtain an efficient delivery of macromolecule such as siRNA, a sophisticated design of vector is needed. It must be retained to the active uptake by reticuloendothelial system (RES) in the bloodstream and it can release its content inside the cellular target site. In this study, we attempted to design a vector which accommodates the needs. siRNA was encapsulated in the liposomes and its surface was shielded with polyethylene glycol (PEG) moiety to avoid recognizing by RES system. To facilitate cellular internalization, newly synthetizing peptide was attached to tip end of PEG moiety. As results, blood concentration of PEG‐modified liposomes was higher than that of unmodified PEG. Results by confocal laser scanning microscopy studies exhibited PEG‐coated nanodevice can escape from endosomes in both two types PEG used, shorter and longer one. However, prominent cytosolic release of siRNA was only shown by the use of shorter PEG type. These results were in line with gene silencing study in which shorter P...

Modulation of Endosomal Escape of IRQ‐PEGylated Nano‐carrier

The novel IRQ peptide is one of cell penetrating peptides (CPPs) that has ability to induce endosomal escape. It has been demonstrated that IRQ ligand had ability to facilitate an escape of liposomes encapsulating siRNA from the endosomes presumably by fusion‐independent mechanism [1,2]. In the present study, we attempted to modulate the intracellular trafficking of IRQ‐modified nano‐carrier in term of escaping process by changing the lipid composition. The peptide was attached to the terminal end of maleimide group of polyethylene glycol‐modified liposomes (IRQ‐PEG‐Lip). The liposomes were composed of DOTAP, DOPE and cholesterol and it was labeled by water soluble sulpho‐rhodamine B (Sr‐B). The escape of PEG‐coated liposomes was then observed by confocal laser scanning microscope after the endosomes were stained with Lysosensor. The results exhibited that IRQ‐PEG‐Lip was escaped from endosomal compartment after 1 h transfection when 40% of DOPE was incorporated into the nanostructure comparing to that of...