Page 606 - Book Hosokawa Nanoparticle Technology Handbook

APPLICATIONS 38 EXPRESSION OF OPTICAL FUNCTION
although the immunization rate for vaccine is low in 3. By replacing liver cell-binding sites presented
Japan but high in the United States and Europe. on the surface for another living organism
Therefore, it is necessary to complete stealth BNC by recognition molecule, pinpoint delivery to the
mimicking the amino acid mutated part of the
Hepatitis B virus escape variant, which is hardly rec- targeted cell is made possible.
ognized by the human immune system.
Electroporation, the conventional method of A drug BNC that is capable of excellent pinpoint
including materials into BNC, is unsuitable for delivery is sought to become a carrier that can be used
including large molecules due to the variation in for drug and gene therapy.
reproducibility. The electroporation is carried out The findings of BNC introduced here are results
only by manual operation, which is a major obstacle from a collaborative study of Masaharu Seno
in producing a medical drug.Therefore, efforts are (Okayama University), Akihiko Kondo (Kobe
being made to reduce the dosage by the improved University), Masakazu Ueda (Keio University),
method, (e.g., lipsome-mediated method) which will Katsuyuki Tanizawa (Osaka University). The practical
realize inclusion with much greater efficiency than application of this study is proceeding with Beacle,
electroporation. In addition, safety and the dynamic Inc. which is a university venture, established by the
state in the human body are being studied. authors.

4. Conclusion

There have been a number of studies on carriers for References
DDS such as retrovirus and adenovirus, liposome and
fusogenic forms of hemagglutination virus of Japan [1] H. Sezaki: Drug Delivery System, Hirokawa, Tokyo
and liposomes. However, few carriers have been com- (1989).
mercialized after clinical testing. [2] E. Marshall: Sciences, 298, 32 (2002).
To date, BNC with the following features have been [3] J. Savulescu: J. Med. Ethics, 27, 148 (2001).
developed. [4] T. Yamada, Y. Iwasaki, H. Tada, H. Iwabuki, M.K.L.
Chuah, T.V. Driessche, H. Fukuda, A. Kondo, M. Ueda,
1. Liver cell-binding site by HBsAg (Pre-S1 region) M. Seno, K. Tanizawa and S. Kuroda: Nat. Biotechnol.,
indicates specific binding with human liver cells. 21, 885–890 (2003).
2. As it does not include genes derived from a virus, [5] S. Kuroda, S. Otaka, T. Miyazaki, M. Nakao and
it is not pathogenic. Y. Fujisawa: J. Biol. Chem., 267, 1953–1961 (1992).

APPLICATION 38

38 EXPRESSION OF OPTICAL FUNCTION BY NANOSTRUCTURE USING
FEMTOSECOND LASER PROCESSING

It is well known that laser light can be pulsed and pulse energy is 1 J. The photo-induced reaction is
focused to a spot of wavelength order. Ultrashort expected to occur only near the focused part of the
pulsed lasers have been used as powerful tools to clar- laser beam due to multiphoton processes.
ify elementary processes, such as excitation-energy
relaxation and both electron and proton transfer on
nanosecond and picosecond time scales that occur in 1. Space selective valence state manipulation of rare
a micrometer-sized area. In addition, ultrashort pulsed earth ions inside glasses
laser can be used to make microscopic modifications
to transparent materials [1–9]. The reason for using The authors have observed space-selective room-
this laser is that the strength of its electric field can temperature permanent photoreduction of rare-earth
3
2
2
reach 100 TW/cm , which is sufficient for inducing ions of Sm to Sm in glasses by an infrared fem-
nonlinear optical effects in materials by use of a tosecond laser. Room-temperature permanent pho-
3
2
focusing lens, when the pulse width is 100 fs and the toreduction of Sm to Sm was observed in borate
578