title: Recent advances in two-photon photodynamic therapy.
abstract: Photodynamic therapy (PDT) is a treatment for tumors and accepted in several countries in the world. Introduction of two-photon absortion (2PA) into PDT allows spatially selective treatment of cancers. Possibilities and limitations of the use of two-photon excitation in PDT are discussed, and many literatures in this area are reviewed. The conclusions are that 2PA-PDT has an advantage for higher selectivity than one-photon absorption PDT, and femtosecond pulsed laser is more suitable for 2PA-PDT than pico- and nanosecond pulses. However, most of photosensitizers used in the past studies had low 2PA cross section values less than 50 GM, and resulted in a low PDT efficiency under two-photon irradiation conditions. To realize 2PA-PDT, much larger 2PA cross sections must be required.
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ogawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kobuke
mesh_terms: D000818:Animals; D006801:Humans; D053685:Laser Therapy; D009369:Neoplasms / Q000628:therapy*; D010778:Photochemotherapy / Q000295:instrumentation / Q000639:trends*; D017785:Photons